golang alldocs 代码
文件路径：/src/cmd/go/alldocs.go
/ Copyright 2011 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
/ Code generated by mkalldocs.sh; DO NOT EDIT.
/ Edit the documentation in other files and rerun mkalldocs.sh to generate this one.
/ Go is a tool for managing Go source code.
/
/ Usage:
/
/ go <command> [arguments]
/
/ The commands are:
/
/ bug start a bug report
/ build compile packages and dependencies
/ clean remove object files and cached files
/ doc show documentation for package or symbol
/ env print Go environment information
/ fix update packages to use new APIs
/ fmt gofmt (reformat) package sources
/ generate generate Go files by processing source
/ get add dependencies to current module and install them
/ install compile and install packages and dependencies
/ list list packages or modules
/ mod module maintenance
/ work workspace maintenance
/ run compile and run Go program
/ test test packages
/ tool run specified go tool
/ version print Go version
/ vet report likely mistakes in packages
/
/ Use "go help <command>" for more information about a command.
/
/ Additional help topics:
/
/ buildconstraint build constraints
/ buildmode build modes
/ c calling between Go and C
/ cache build and test caching
/ environment environment variables
/ filetype file types
/ go.mod the go.mod file
/ gopath GOPATH environment variable
/ gopath-get legacy GOPATH go get
/ goproxy module proxy protocol
/ importpath import path syntax
/ modules modules, module versions, and more
/ module-get module-aware go get
/ module-auth module authentication using go.sum
/ packages package lists and patterns
/ private configuration for downloading non-public code
/ testflag testing flags
/ testfunc testing functions
/ vcs controlling version control with GOVCS
/
/ Use "go help <topic>" for more information about that topic.
/
/ # Start a bug report
/
/ Usage:
/
/ go bug
/
/ Bug opens the default browser and starts a new bug report.
/ The report includes useful system information.
/
/ # Compile packages and dependencies
/
/ Usage:
/
/ go build [-o output] [build flags] [packages]
/
/ Build compiles the packages named by the import paths,
/ along with their dependencies, but it does not install the results.
/
/ If the arguments to build are a list of .go files from a single directory,
/ build treats them as a list of source files specifying a single package.
/
/ When compiling packages, build ignores files that end in '_test.go'.
/
/ When compiling a single main package, build writes
/ the resulting executable to an output file named after
/ the first source file ('go build ed.go rx.go' writes 'ed' or 'ed.exe')
/ or the source code directory ('go build unix/sam' writes 'sam' or 'sam.exe').
/ The '.exe' suffix is added when writing a Windows executable.
/
/ When compiling multiple packages or a single non-main package,
/ build compiles the packages but discards the resulting object,
/ serving only as a check that the packages can be built.
/
/ The -o flag forces build to write the resulting executable or object
/ to the named output file or directory, instead of the default behavior described
/ in the last two paragraphs. If the named output is an existing directory or
/ ends with a slash or backslash, then any resulting executables
/ will be written to that directory.
/
/ The -i flag installs the packages that are dependencies of the target.
/ The -i flag is deprecated. Compiled packages are cached automatically.
/
/ The build flags are shared by the build, clean, get, install, list, run,
/ and test commands:
/
/ -a
/ force rebuilding of packages that are already up-to-date.
/ -n
/ print the commands but do not run them.
/ -p n
/ the number of programs, such as build commands or
/ test binaries, that can be run in parallel.
/ The default is GOMAXPROCS, normally the number of CPUs available.
/ -race
/ enable data race detection.
/ Supported only on linux/amd64, freebsd/amd64, darwin/amd64, darwin/arm64, windows/amd64,
/ linux/ppc64le and linux/arm64 (only for 48-bit VMA).
/ -msan
/ enable interoperation with memory sanitizer.
/ Supported only on linux/amd64, linux/arm64
/ and only with Clang/LLVM as the host C compiler.
/ On linux/arm64, pie build mode will be used.
/ -asan
/ enable interoperation with address sanitizer.
/ Supported only on linux/arm64, linux/amd64.
/ Supported only on linux/amd64 or linux/arm64 and only with GCC 7 and higher
/ or Clang/LLVM 9 and higher.
/ -v
/ print the names of packages as they are compiled.
/ -work
/ print the name of the temporary work directory and
/ do not delete it when exiting.
/ -x
/ print the commands.
/
/ -asmflags '[pattern=]arg list'
/ arguments to pass on each go tool asm invocation.
/ -buildmode mode
/ build mode to use. See 'go help buildmode' for more.
/ -buildvcs
/ Whether to stamp binaries with version control information
/ ("true", "false", or "auto"). By default ("auto"), version control
/ information is stamped into a binary if the main package, the main module
/ containing it, and the current directory are all in the same repository.
/ Use -buildvcs=false to always omit version control information, or
/ -buildvcs=true to error out if version control information is available but
/ cannot be included due to a missing tool or ambiguous directory structure.
/ -compiler name
/ name of compiler to use, as in runtime.Compiler (gccgo or gc).
/ -gccgoflags '[pattern=]arg list'
/ arguments to pass on each gccgo compiler/linker invocation.
/ -gcflags '[pattern=]arg list'
/ arguments to pass on each go tool compile invocation.
/ -installsuffix suffix
/ a suffix to use in the name of the package installation directory,
/ in order to keep output separate from default builds.
/ If using the -race flag, the install suffix is automatically set to race
/ or, if set explicitly, has _race appended to it. Likewise for the -msan
/ and -asan flags. Using a -buildmode option that requires non-default compile
/ flags has a similar effect.
/ -ldflags '[pattern=]arg list'
/ arguments to pass on each go tool link invocation.
/ -linkshared
/ build code that will be linked against shared libraries previously
/ created with -buildmode=shared.
/ -mod mode
/ module download mode to use: readonly, vendor, or mod.
/ By default, if a vendor directory is present and the go version in go.mod
/ is 1.14 or higher, the go command acts as if -mod=vendor were set.
/ Otherwise, the go command acts as if -mod=readonly were set.
/ See https://golang.org/ref/mod#build-commands for details.
/ -modcacherw
/ leave newly-created directories in the module cache read-write
/ instead of making them read-only.
/ -modfile file
/ in module aware mode, read (and possibly write) an alternate go.mod
/ file instead of the one in the module root directory. A file named
/ "go.mod" must still be present in order to determine the module root
/ directory, but it is not accessed. When -modfile is specified, an
/ alternate go.sum file is also used: its path is derived from the
/ -modfile flag by trimming the ".mod" extension and appending ".sum".
/ -overlay file
/ read a JSON config file that provides an overlay for build operations.
/ The file is a JSON struct with a single field, named 'Replace', that
/ maps each disk file path (a string) to its backing file path, so that
/ a build will run as if the disk file path exists with the contents
/ given by the backing file paths, or as if the disk file path does not
/ exist if its backing file path is empty. Support for the -overlay flag
/ has some limitations: importantly, cgo files included from outside the
/ include path must be in the same directory as the Go package they are
/ included from, and overlays will not appear when binaries and tests are
/ run through go run and go test respectively.
/ -pkgdir dir
/ install and load all packages from dir instead of the usual locations.
/ For example, when building with a non-standard configuration,
/ use -pkgdir to keep generated packages in a separate location.
/ -tags tag,list
/ a comma-separated list of additional build tags to consider satisfied
/ during the build. For more information about build tags, see
/ 'go help buildconstraint'. (Earlier versions of Go used a
/ space-separated list, and that form is deprecated but still recognized.)
/ -trimpath
/ remove all file system paths from the resulting executable.
/ Instead of absolute file system paths, the recorded file names
/ will begin either a module path@version (when using modules),
/ or a plain import path (when using the standard library, or GOPATH).
/ -toolexec 'cmd args'
/ a program to use to invoke toolchain programs like vet and asm.
/ For example, instead of running asm, the go command will run
/ 'cmd args /path/to/asm <arguments for asm>'.
/ The TOOLEXEC_IMPORTPATH environment variable will be set,
/ matching 'go list -f {{.ImportPath}}' for the package being built.
/
/ The -asmflags, -gccgoflags, -gcflags, and -ldflags flags accept a
/ space-separated list of arguments to pass to an underlying tool
/ during the build. To embed spaces in an element in the list, surround
/ it with either single or double quotes. The argument list may be
/ preceded by a package pattern and an equal sign, which restricts
/ the use of that argument list to the building of packages matching
/ that pattern (see 'go help packages' for a description of package
/ patterns). Without a pattern, the argument list applies only to the
/ packages named on the command line. The flags may be repeated
/ with different patterns in order to specify different arguments for
/ different sets of packages. If a package matches patterns given in
/ multiple flags, the latest match on the command line wins.
/ For example, 'go build -gcflags=-S fmt' prints the disassembly
/ only for package fmt, while 'go build -gcflags=all=-S fmt'
/ prints the disassembly for fmt and all its dependencies.
/
/ For more about specifying packages, see 'go help packages'.
/ For more about where packages and binaries are installed,
/ run 'go help gopath'.
/ For more about calling between Go and C/C++, run 'go help c'.
/
/ Note: Build adheres to certain conventions such as those described
/ by 'go help gopath'. Not all projects can follow these conventions,
/ however. Installations that have their own conventions or that use
/ a separate software build system may choose to use lower-level
/ invocations such as 'go tool compile' and 'go tool link' to avoid
/ some of the overheads and design decisions of the build tool.
/
/ See also: go install, go get, go clean.
/
/ # Remove object files and cached files
/
/ Usage:
/
/ go clean [clean flags] [build flags] [packages]
/
/ Clean removes object files from package source directories.
/ The go command builds most objects in a temporary directory,
/ so go clean is mainly concerned with object files left by other
/ tools or by manual invocations of go build.
/
/ If a package argument is given or the -i or -r flag is set,
/ clean removes the following files from each of the
/ source directories corresponding to the import paths:
/
/ _obj/ old object directory, left from Makefiles
/ _test/ old test directory, left from Makefiles
/ _testmain.go old gotest file, left from Makefiles
/ test.out old test log, left from Makefiles
/ build.out old test log, left from Makefiles
/ *.[568ao] object files, left from Makefiles
/
/ DIR(.exe) from go build
/ DIR.test(.exe) from go test -c
/ MAINFILE(.exe) from go build MAINFILE.go
/ *.so from SWIG
/
/ In the list, DIR represents the final path element of the
/ directory, and MAINFILE is the base name of any Go source
/ file in the directory that is not included when building
/ the package.
/
/ The -i flag causes clean to remove the corresponding installed
/ archive or binary (what 'go install' would create).
/
/ The -n flag causes clean to print the remove commands it would execute,
/ but not run them.
/
/ The -r flag causes clean to be applied recursively to all the
/ dependencies of the packages named by the import paths.
/
/ The -x flag causes clean to print remove commands as it executes them.
/
/ The -cache flag causes clean to remove the entire go build cache.
/
/ The -testcache flag causes clean to expire all test results in the
/ go build cache.
/
/ The -modcache flag causes clean to remove the entire module
/ download cache, including unpacked source code of versioned
/ dependencies.
/
/ The -fuzzcache flag causes clean to remove files stored in the Go build
/ cache for fuzz testing. The fuzzing engine caches files that expand
/ code coverage, so removing them may make fuzzing less effective until
/ new inputs are found that provide the same coverage. These files are
/ distinct from those stored in testdata directory; clean does not remove
/ those files.
/
/ For more about build flags, see 'go help build'.
/
/ For more about specifying packages, see 'go help packages'.
/
/ # Show documentation for package or symbol
/
/ Usage:
/
/ go doc [doc flags] [package|[package.]symbol[.methodOrField]]
/
/ Doc prints the documentation comments associated with the item identified by its
/ arguments (a package, const, func, type, var, method, or struct field)
/ followed by a one-line summary of each of the first-level items "under"
/ that item (package-level declarations for a package, methods for a type,
/ etc.).
/
/ Doc accepts zero, one, or two arguments.
/
/ Given no arguments, that is, when run as
/
/ go doc
/
/ it prints the package documentation for the package in the current directory.
/ If the package is a command (package main), the exported symbols of the package
/ are elided from the presentation unless the -cmd flag is provided.
/
/ When run with one argument, the argument is treated as a Go-syntax-like
/ representation of the item to be documented. What the argument selects depends
/ on what is installed in GOROOT and GOPATH, as well as the form of the argument,
/ which is schematically one of these:
/
/ go doc <pkg>
/ go doc <sym>[.<methodOrField>]
/ go doc [<pkg>.]<sym>[.<methodOrField>]
/ go doc [<pkg>.][<sym>.]<methodOrField>
/
/ The first item in this list matched by the argument is the one whose documentation
/ is printed. (See the examples below.) However, if the argument starts with a capital
/ letter it is assumed to identify a symbol or method in the current directory.
/
/ For packages, the order of scanning is determined lexically in breadth-first order.
/ That is, the package presented is the one that matches the search and is nearest
/ the root and lexically first at its level of the hierarchy. The GOROOT tree is
/ always scanned in its entirety before GOPATH.
/
/ If there is no package specified or matched, the package in the current
/ directory is selected, so "go doc Foo" shows the documentation for symbol Foo in
/ the current package.
/
/ The package path must be either a qualified path or a proper suffix of a
/ path. The go tool's usual package mechanism does not apply: package path
/ elements like . and ... are not implemented by go doc.
/
/ When run with two arguments, the first is a package path (full path or suffix),
/ and the second is a symbol, or symbol with method or struct field:
/
/ go doc <pkg> <sym>[.<methodOrField>]
/
/ In all forms, when matching symbols, lower-case letters in the argument match
/ either case but upper-case letters match exactly. This means that there may be
/ multiple matches of a lower-case argument in a package if different symbols have
/ different cases. If this occurs, documentation for all matches is printed.
/
/ Examples:
/
/ go doc
/ Show documentation for current package.
/ go doc Foo
/ Show documentation for Foo in the current package.
/ (Foo starts with a capital letter so it cannot match
/ a package path.)
/ go doc encoding/json
/ Show documentation for the encoding/json package.
/ go doc json
/ Shorthand for encoding/json.
/ go doc json.Number (or go doc json.number)
/ Show documentation and method summary for json.Number.
/ go doc json.Number.Int64 (or go doc json.number.int64)
/ Show documentation for json.Number's Int64 method.
/ go doc cmd/doc
/ Show package docs for the doc command.
/ go doc -cmd cmd/doc
/ Show package docs and exported symbols within the doc command.
/ go doc template.new
/ Show documentation for html/template's New function.
/ (html/template is lexically before text/template)
/ go doc text/template.new # One argument
/ Show documentation for text/template's New function.
/ go doc text/template new # Two arguments
/ Show documentation for text/template's New function.
/
/ At least in the current tree, these invocations all print the
/ documentation for json.Decoder's Decode method:
/
/ go doc json.Decoder.Decode
/ go doc json.decoder.decode
/ go doc json.decode
/ cd go/src/encoding/json; go doc decode
/
/ Flags:
/
/ -all
/ Show all the documentation for the package.
/ -c
/ Respect case when matching symbols.
/ -cmd
/ Treat a command (package main) like a regular package.
/ Otherwise package main's exported symbols are hidden
/ when showing the package's top-level documentation.
/ -short
/ One-line representation for each symbol.
/ -src
/ Show the full source code for the symbol. This will
/ display the full Go source of its declaration and
/ definition, such as a function definition (including
/ the body), type declaration or enclosing const
/ block. The output may therefore include unexported
/ details.
/ -u
/ Show documentation for unexported as well as exported
/ symbols, methods, and fields.
/
/ # Print Go environment information
/
/ Usage:
/
/ go env [-json] [-u] [-w] [var ...]
/
/ Env prints Go environment information.
/
/ By default env prints information as a shell script
/ (on Windows, a batch file). If one or more variable
/ names is given as arguments, env prints the value of
/ each named variable on its own line.
/
/ The -json flag prints the environment in JSON format
/ instead of as a shell script.
/
/ The -u flag requires one or more arguments and unsets
/ the default setting for the named environment variables,
/ if one has been set with 'go env -w'.
/
/ The -w flag requires one or more arguments of the
/ form NAME=VALUE and changes the default settings
/ of the named environment variables to the given values.
/
/ For more about environment variables, see 'go help environment'.
/
/ # Update packages to use new APIs
/
/ Usage:
/
/ go fix [-fix list] [packages]
/
/ Fix runs the Go fix command on the packages named by the import paths.
/
/ The -fix flag sets a comma-separated list of fixes to run.
/ The default is all known fixes.
/ (Its value is passed to 'go tool fix -r'.)
/
/ For more about fix, see 'go doc cmd/fix'.
/ For more about specifying packages, see 'go help packages'.
/
/ To run fix with other options, run 'go tool fix'.
/
/ See also: go fmt, go vet.
/
/ # Gofmt (reformat) package sources
/
/ Usage:
/
/ go fmt [-n] [-x] [packages]
/
/ Fmt runs the command 'gofmt -l -w' on the packages named
/ by the import paths. It prints the names of the files that are modified.
/
/ For more about gofmt, see 'go doc cmd/gofmt'.
/ For more about specifying packages, see 'go help packages'.
/
/ The -n flag prints commands that would be executed.
/ The -x flag prints commands as they are executed.
/
/ The -mod flag's value sets which module download mode
/ to use: readonly or vendor. See 'go help modules' for more.
/
/ To run gofmt with specific options, run gofmt itself.
/
/ See also: go fix, go vet.
/
/ # Generate Go files by processing source
/
/ Usage:
/
/ go generate [-run regexp] [-n] [-v] [-x] [build flags] [file.go... | packages]
/
/ Generate runs commands described by directives within existing
/ files. Those commands can run any process but the intent is to
/ create or update Go source files.
/
/ Go generate is never run automatically by go build, go test,
/ and so on. It must be run explicitly.
/
/ Go generate scans the file for directives, which are lines of
/ the form,
/
/ /go:generate command argument...
/
/ (note: no leading spaces and no space in "/go") where command
/ is the generator to be run, corresponding to an executable file
/ that can be run locally. It must either be in the shell path
/ (gofmt), a fully qualified path (/usr/you/bin/mytool), or a
/ command alias, described below.
/
/ Note that go generate does not parse the file, so lines that look
/ like directives in comments or multiline strings will be treated
/ as directives.
/
/ The arguments to the directive are space-separated tokens or
/ double-quoted strings passed to the generator as individual
/ arguments when it is run.
/
/ Quoted strings use Go syntax and are evaluated before execution; a
/ quoted string appears as a single argument to the generator.
/
/ To convey to humans and machine tools that code is generated,
/ generated source should have a line that matches the following
/ regular expression (in Go syntax):
/
/ ^/ Code generated .* DO NOT EDIT\.$
/
/ This line must appear before the first non-comment, non-blank
/ text in the file.
/
/ Go generate sets several variables when it runs the generator:
/
/ $GOARCH
/ The execution architecture (arm, amd64, etc.)
/ $GOOS
/ The execution operating system (linux, windows, etc.)
/ $GOFILE
/ The base name of the file.
/ $GOLINE
/ The line number of the directive in the source file.
/ $GOPACKAGE
/ The name of the package of the file containing the directive.
/ $GOROOT
/ The GOROOT directory for the 'go' command that invoked the
/ generator, containing the Go toolchain and standard library.
/ $DOLLAR
/ A dollar sign.
/
/ Other than variable substitution and quoted-string evaluation, no
/ special processing such as "globbing" is performed on the command
/ line.
/
/ As a last step before running the command, any invocations of any
/ environment variables with alphanumeric names, such as $GOFILE or
/ $HOME, are expanded throughout the command line. The syntax for
/ variable expansion is $NAME on all operating systems. Due to the
/ order of evaluation, variables are expanded even inside quoted
/ strings. If the variable NAME is not set, $NAME expands to the
/ empty string.
/
/ A directive of the form,
/
/ /go:generate -command xxx args...
/
/ specifies, for the remainder of this source file only, that the
/ string xxx represents the command identified by the arguments. This
/ can be used to create aliases or to handle multiword generators.
/ For example,
/
/ /go:generate -command foo go tool foo
/
/ specifies that the command "foo" represents the generator
/ "go tool foo".
/
/ Generate processes packages in the order given on the command line,
/ one at a time. If the command line lists .go files from a single directory,
/ they are treated as a single package. Within a package, generate processes the
/ source files in a package in file name order, one at a time. Within
/ a source file, generate runs generators in the order they appear
/ in the file, one at a time. The go generate tool also sets the build
/ tag "generate" so that files may be examined by go generate but ignored
/ during build.
/
/ For packages with invalid code, generate processes only source files with a
/ valid package clause.
/
/ If any generator returns an error exit status, "go generate" skips
/ all further processing for that package.
/
/ The generator is run in the package's source directory.
/
/ Go generate accepts one specific flag:
/
/ -run=""
/ if non-empty, specifies a regular expression to select
/ directives whose full original source text (excluding
/ any trailing spaces and final newline) matches the
/ expression.
/
/ It also accepts the standard build flags including -v, -n, and -x.
/ The -v flag prints the names of packages and files as they are
/ processed.
/ The -n flag prints commands that would be executed.
/ The -x flag prints commands as they are executed.
/
/ For more about build flags, see 'go help build'.
/
/ For more about specifying packages, see 'go help packages'.
/
/ # Add dependencies to current module and install them
/
/ Usage:
/
/ go get [-t] [-u] [-v] [build flags] [packages]
/
/ Get resolves its command-line arguments to packages at specific module versions,
/ updates go.mod to require those versions, and downloads source code into the
/ module cache.
/
/ To add a dependency for a package or upgrade it to its latest version:
/
/ go get example.com/pkg
/
/ To upgrade or downgrade a package to a specific version:
/
/ go get example.com/pkg@v1.2.3
/
/ To remove a dependency on a module and downgrade modules that require it:
/
/ go get example.com/mod@none
/
/ See https://golang.org/ref/mod#go-get for details.
/
/ In earlier versions of Go, 'go get' was used to build and install packages.
/ Now, 'go get' is dedicated to adjusting dependencies in go.mod. 'go install'
/ may be used to build and install commands instead. When a version is specified,
/ 'go install' runs in module-aware mode and ignores the go.mod file in the
/ current directory. For example:
/
/ go install example.com/pkg@v1.2.3
/ go install example.com/pkg@latest
/
/ See 'go help install' or https://golang.org/ref/mod#go-install for details.
/
/ 'go get' accepts the following flags.
/
/ The -t flag instructs get to consider modules needed to build tests of
/ packages specified on the command line.
/
/ The -u flag instructs get to update modules providing dependencies
/ of packages named on the command line to use newer minor or patch
/ releases when available.
/
/ The -u=patch flag (not -u patch) also instructs get to update dependencies,
/ but changes the default to select patch releases.
/
/ When the -t and -u flags are used together, get will update
/ test dependencies as well.
/
/ The -x flag prints commands as they are executed. This is useful for
/ debugging version control commands when a module is downloaded directly
/ from a repository.
/
/ For more about modules, see https://golang.org/ref/mod.
/
/ For more about specifying packages, see 'go help packages'.
/
/ This text describes the behavior of get using modules to manage source
/ code and dependencies. If instead the go command is running in GOPATH
/ mode, the details of get's flags and effects change, as does 'go help get'.
/ See 'go help gopath-get'.
/
/ See also: go build, go install, go clean, go mod.
/
/ # Compile and install packages and dependencies
/
/ Usage:
/
/ go install [build flags] [packages]
/
/ Install compiles and installs the packages named by the import paths.
/
/ Executables are installed in the directory named by the GOBIN environment
/ variable, which defaults to $GOPATH/bin or $HOME/go/bin if the GOPATH
/ environment variable is not set. Executables in $GOROOT
/ are installed in $GOROOT/bin or $GOTOOLDIR instead of $GOBIN.
/
/ If the arguments have version suffixes (like @latest or @v1.0.0), "go install"
/ builds packages in module-aware mode, ignoring the go.mod file in the current
/ directory or any parent directory, if there is one. This is useful for
/ installing executables without affecting the dependencies of the main module.
/ To eliminate ambiguity about which module versions are used in the build, the
/ arguments must satisfy the following constraints:
/
/ - Arguments must be package paths or package patterns (with "..." wildcards).
/ They must not be standard packages (like fmt), meta-patterns (std, cmd,
/ all), or relative or absolute file paths.
/
/ - All arguments must have the same version suffix. Different queries are not
/ allowed, even if they refer to the same version.
/
/ - All arguments must refer to packages in the same module at the same version.
/
/ - Package path arguments must refer to main packages. Pattern arguments
/ will only match main packages.
/
/ - No module is considered the "main" module. If the module containing
/ packages named on the command line has a go.mod file, it must not contain
/ directives (replace and exclude) that would cause it to be interpreted
/ differently than if it were the main module. The module must not require
/ a higher version of itself.
/
/ - Vendor directories are not used in any module. (Vendor directories are not
/ included in the module zip files downloaded by 'go install'.)
/
/ If the arguments don't have version suffixes, "go install" may run in
/ module-aware mode or GOPATH mode, depending on the GO111MODULE environment
/ variable and the presence of a go.mod file. See 'go help modules' for details.
/ If module-aware mode is enabled, "go install" runs in the context of the main
/ module.
/
/ When module-aware mode is disabled, other packages are installed in the
/ directory $GOPATH/pkg/$GOOS_$GOARCH. When module-aware mode is enabled,
/ other packages are built and cached but not installed.
/
/ The -i flag installs the dependencies of the named packages as well.
/ The -i flag is deprecated. Compiled packages are cached automatically.
/
/ For more about the build flags, see 'go help build'.
/ For more about specifying packages, see 'go help packages'.
/
/ See also: go build, go get, go clean.
/
/ # List packages or modules
/
/ Usage:
/
/ go list [-f format] [-json] [-m] [list flags] [build flags] [packages]
/
/ List lists the named packages, one per line.
/ The most commonly-used flags are -f and -json, which control the form
/ of the output printed for each package. Other list flags, documented below,
/ control more specific details.
/
/ The default output shows the package import path:
/
/ bytes
/ encoding/json
/ github.com/gorilla/mux
/ golang.org/x/net/html
/
/ The -f flag specifies an alternate format for the list, using the
/ syntax of package template. The default output is equivalent
/ to -f '{{.ImportPath}}'. The struct being passed to the template is:
/
/ type Package struct {
/ Dir string / directory containing package sources
/ ImportPath string / import path of package in dir
/ ImportComment string / path in import comment on package statement
/ Name string / package name
/ Doc string / package documentation string
/ Target string / install path
/ Shlib string / the shared library that contains this package (only set when -linkshared)
/ Goroot bool / is this package in the Go root?
/ Standard bool / is this package part of the standard Go library?
/ Stale bool / would 'go install' do anything for this package?
/ StaleReason string / explanation for Stale==true
/ Root string / Go root or Go path dir containing this package
/ ConflictDir string / this directory shadows Dir in $GOPATH
/ BinaryOnly bool / binary-only package (no longer supported)
/ ForTest string / package is only for use in named test
/ Export string / file containing export data (when using -export)
/ BuildID string / build ID of the compiled package (when using -export)
/ Module *Module / info about package's containing module, if any (can be nil)
/ Match []string / command-line patterns matching this package
/ DepOnly bool / package is only a dependency, not explicitly listed
/
/ / Source files
/ GoFiles []string / .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
/ CgoFiles []string / .go source files that import "C"
/ CompiledGoFiles []string / .go files presented to compiler (when using -compiled)
/ IgnoredGoFiles []string / .go source files ignored due to build constraints
/ IgnoredOtherFiles []string / non-.go source files ignored due to build constraints
/ CFiles []string / .c source files
/ CXXFiles []string / .cc, .cxx and .cpp source files
/ MFiles []string / .m source files
/ HFiles []string / .h, .hh, .hpp and .hxx source files
/ FFiles []string / .f, .F, .for and .f90 Fortran source files
/ SFiles []string / .s source files
/ SwigFiles []string / .swig files
/ SwigCXXFiles []string / .swigcxx files
/ SysoFiles []string / .syso object files to add to archive
/ TestGoFiles []string / _test.go files in package
/ XTestGoFiles []string / _test.go files outside package
/
/ / Embedded files
/ EmbedPatterns []string / /go:embed patterns
/ EmbedFiles []string / files matched by EmbedPatterns
/ TestEmbedPatterns []string / /go:embed patterns in TestGoFiles
/ TestEmbedFiles []string / files matched by TestEmbedPatterns
/ XTestEmbedPatterns []string / /go:embed patterns in XTestGoFiles
/ XTestEmbedFiles []string / files matched by XTestEmbedPatterns
/
/ / Cgo directives
/ CgoCFLAGS []string / cgo: flags for C compiler
/ CgoCPPFLAGS []string / cgo: flags for C preprocessor
/ CgoCXXFLAGS []string / cgo: flags for C++ compiler
/ CgoFFLAGS []string / cgo: flags for Fortran compiler
/ CgoLDFLAGS []string / cgo: flags for linker
/ CgoPkgConfig []string / cgo: pkg-config names
/
/ / Dependency information
/ Imports []string / import paths used by this package
/ ImportMap map[string]string / map from source import to ImportPath (identity entries omitted)
/ Deps []string / all (recursively) imported dependencies
/ TestImports []string / imports from TestGoFiles
/ XTestImports []string / imports from XTestGoFiles
/
/ / Error information
/ Incomplete bool / this package or a dependency has an error
/ Error *PackageError / error loading package
/ DepsErrors []*PackageError / errors loading dependencies
/ }
/
/ Packages stored in vendor directories report an ImportPath that includes the
/ path to the vendor directory (for example, "d/vendor/p" instead of "p"),
/ so that the ImportPath uniquely identifies a given copy of a package.
/ The Imports, Deps, TestImports, and XTestImports lists also contain these
/ expanded import paths. See golang.org/s/go15vendor for more about vendoring.
/
/ The error information, if any, is
/
/ type PackageError struct {
/ ImportStack []string / shortest path from package named on command line to this one
/ Pos string / position of error (if present, file:line:col)
/ Err string / the error itself
/ }
/
/ The module information is a Module struct, defined in the discussion
/ of list -m below.
/
/ The template function "join" calls strings.Join.
/
/ The template function "context" returns the build context, defined as:
/
/ type Context struct {
/ GOARCH string / target architecture
/ GOOS string / target operating system
/ GOROOT string / Go root
/ GOPATH string / Go path
/ CgoEnabled bool / whether cgo can be used
/ UseAllFiles bool / use files regardless of +build lines, file names
/ Compiler string / compiler to assume when computing target paths
/ BuildTags []string / build constraints to match in +build lines
/ ToolTags []string / toolchain-specific build constraints
/ ReleaseTags []string / releases the current release is compatible with
/ InstallSuffix string / suffix to use in the name of the install dir
/ }
/
/ For more information about the meaning of these fields see the documentation
/ for the go/build package's Context type.
/
/ The -json flag causes the package data to be printed in JSON format
/ instead of using the template format. The JSON flag can optionally be
/ provided with a set of comma-separated required field names to be output.
/ If so, those required fields will always appear in JSON output, but
/ others may be omitted to save work in computing the JSON struct.
/
/ The -compiled flag causes list to set CompiledGoFiles to the Go source
/ files presented to the compiler. Typically this means that it repeats
/ the files listed in GoFiles and then also adds the Go code generated
/ by processing CgoFiles and SwigFiles. The Imports list contains the
/ union of all imports from both GoFiles and CompiledGoFiles.
/
/ The -deps flag causes list to iterate over not just the named packages
/ but also all their dependencies. It visits them in a depth-first post-order
/ traversal, so that a package is listed only after all its dependencies.
/ Packages not explicitly listed on the command line will have the DepOnly
/ field set to true.
/
/ The -e flag changes the handling of erroneous packages, those that
/ cannot be found or are malformed. By default, the list command
/ prints an error to standard error for each erroneous package and
/ omits the packages from consideration during the usual printing.
/ With the -e flag, the list command never prints errors to standard
/ error and instead processes the erroneous packages with the usual
/ printing. Erroneous packages will have a non-empty ImportPath and
/ a non-nil Error field; other information may or may not be missing
/ (zeroed).
/
/ The -export flag causes list to set the Export field to the name of a
/ file containing up-to-date export information for the given package,
/ and the BuildID field to the build ID of the compiled package.
/
/ The -find flag causes list to identify the named packages but not
/ resolve their dependencies: the Imports and Deps lists will be empty.
/
/ The -test flag causes list to report not only the named packages
/ but also their test binaries (for packages with tests), to convey to
/ source code analysis tools exactly how test binaries are constructed.
/ The reported import path for a test binary is the import path of
/ the package followed by a ".test" suffix, as in "math/rand.test".
/ When building a test, it is sometimes necessary to rebuild certain
/ dependencies specially for that test (most commonly the tested
/ package itself). The reported import path of a package recompiled
/ for a particular test binary is followed by a space and the name of
/ the test binary in brackets, as in "math/rand [math/rand.test]"
/ or "regexp [sort.test]". The ForTest field is also set to the name
/ of the package being tested ("math/rand" or "sort" in the previous
/ examples).
/
/ The Dir, Target, Shlib, Root, ConflictDir, and Export file paths
/ are all absolute paths.
/
/ By default, the lists GoFiles, CgoFiles, and so on hold names of files in Dir
/ (that is, paths relative to Dir, not absolute paths).
/ The generated files added when using the -compiled and -test flags
/ are absolute paths referring to cached copies of generated Go source files.
/ Although they are Go source files, the paths may not end in ".go".
/
/ The -m flag causes list to list modules instead of packages.
/
/ When listing modules, the -f flag still specifies a format template
/ applied to a Go struct, but now a Module struct:
/
/ type Module struct {
/ Path string / module path
/ Query string / version query corresponding to this version
/ Version string / module version
/ Versions []string / available module versions
/ Replace *Module / replaced by this module
/ Time *time.Time / time version was created
/ Update *Module / available update (with -u)
/ Main bool / is this the main module?
/ Indirect bool / module is only indirectly needed by main module
/ Dir string / directory holding local copy of files, if any
/ GoMod string / path to go.mod file describing module, if any
/ GoVersion string / go version used in module
/ Retracted []string / retraction information, if any (with -retracted or -u)
/ Deprecated string / deprecation message, if any (with -u)
/ Error *ModuleError / error loading module
/ Origin any / provenance of module
/ Reuse bool / reuse of old module info is safe
/ }
/
/ type ModuleError struct {
/ Err string / the error itself
/ }
/
/ The file GoMod refers to may be outside the module directory if the
/ module is in the module cache or if the -modfile flag is used.
/
/ The default output is to print the module path and then
/ information about the version and replacement if any.
/ For example, 'go list -m all' might print:
/
/ my/main/module
/ golang.org/x/text v0.3.0 => /tmp/text
/ rsc.io/pdf v0.1.1
/
/ The Module struct has a String method that formats this
/ line of output, so that the default format is equivalent
/ to -f '{{.String}}'.
/
/ Note that when a module has been replaced, its Replace field
/ describes the replacement module, and its Dir field is set to
/ the replacement's source code, if present. (That is, if Replace
/ is non-nil, then Dir is set to Replace.Dir, with no access to
/ the replaced source code.)
/
/ The -u flag adds information about available upgrades.
/ When the latest version of a given module is newer than
/ the current one, list -u sets the Module's Update field
/ to information about the newer module. list -u will also set
/ the module's Retracted field if the current version is retracted.
/ The Module's String method indicates an available upgrade by
/ formatting the newer version in brackets after the current version.
/ If a version is retracted, the string "(retracted)" will follow it.
/ For example, 'go list -m -u all' might print:
/
/ my/main/module
/ golang.org/x/text v0.3.0 [v0.4.0] => /tmp/text
/ rsc.io/pdf v0.1.1 (retracted) [v0.1.2]
/
/ (For tools, 'go list -m -u -json all' may be more convenient to parse.)
/
/ The -versions flag causes list to set the Module's Versions field
/ to a list of all known versions of that module, ordered according
/ to semantic versioning, earliest to latest. The flag also changes
/ the default output format to display the module path followed by the
/ space-separated version list.
/
/ The -retracted flag causes list to report information about retracted
/ module versions. When -retracted is used with -f or -json, the Retracted
/ field will be set to a string explaining why the version was retracted.
/ The string is taken from comments on the retract directive in the
/ module's go.mod file. When -retracted is used with -versions, retracted
/ versions are listed together with unretracted versions. The -retracted
/ flag may be used with or without -m.
/
/ The arguments to list -m are interpreted as a list of modules, not packages.
/ The main module is the module containing the current directory.
/ The active modules are the main module and its dependencies.
/ With no arguments, list -m shows the main module.
/ With arguments, list -m shows the modules specified by the arguments.
/ Any of the active modules can be specified by its module path.
/ The special pattern "all" specifies all the active modules, first the main
/ module and then dependencies sorted by module path.
/ A pattern containing "..." specifies the active modules whose
/ module paths match the pattern.
/ A query of the form path@version specifies the result of that query,
/ which is not limited to active modules.
/ See 'go help modules' for more about module queries.
/
/ The template function "module" takes a single string argument
/ that must be a module path or query and returns the specified
/ module as a Module struct. If an error occurs, the result will
/ be a Module struct with a non-nil Error field.
/
/ When using -m, the -reuse=old.json flag accepts the name of file containing
/ the JSON output of a previous 'go list -m -json' invocation with the
/ same set of modifier flags (such as -u, -retracted, and -versions).
/ The go command may use this file to determine that a module is unchanged
/ since the previous invocation and avoid redownloading information about it.
/ Modules that are not redownloaded will be marked in the new output by
/ setting the Reuse field to true. Normally the module cache provides this
/ kind of reuse automatically; the -reuse flag can be useful on systems that
/ do not preserve the module cache.
/
/ For more about build flags, see 'go help build'.
/
/ For more about specifying packages, see 'go help packages'.
/
/ For more about modules, see https://golang.org/ref/mod.
/
/ # Module maintenance
/
/ Go mod provides access to operations on modules.
/
/ Note that support for modules is built into all the go commands,
/ not just 'go mod'. For example, day-to-day adding, removing, upgrading,
/ and downgrading of dependencies should be done using 'go get'.
/ See 'go help modules' for an overview of module functionality.
/
/ Usage:
/
/ go mod <command> [arguments]
/
/ The commands are:
/
/ download download modules to local cache
/ edit edit go.mod from tools or scripts
/ graph print module requirement graph
/ init initialize new module in current directory
/ tidy add missing and remove unused modules
/ vendor make vendored copy of dependencies
/ verify verify dependencies have expected content
/ why explain why packages or modules are needed
/
/ Use "go help mod <command>" for more information about a command.
/
/ # Download modules to local cache
/
/ Usage:
/
/ go mod download [-x] [-json] [-reuse=old.json] [modules]
/
/ Download downloads the named modules, which can be module patterns selecting
/ dependencies of the main module or module queries of the form path@version.
/
/ With no arguments, download applies to the modules needed to build and test
/ the packages in the main module: the modules explicitly required by the main
/ module if it is at 'go 1.17' or higher, or all transitively-required modules
/ if at 'go 1.16' or lower.
/
/ The go command will automatically download modules as needed during ordinary
/ execution. The "go mod download" command is useful mainly for pre-filling
/ the local cache or to compute the answers for a Go module proxy.
/
/ By default, download writes nothing to standard output. It may print progress
/ messages and errors to standard error.
/
/ The -json flag causes download to print a sequence of JSON objects
/ to standard output, describing each downloaded module (or failure),
/ corresponding to this Go struct:
/
/ type Module struct {
/ Path string / module path
/ Query string / version query corresponding to this version
/ Version string / module version
/ Error string / error loading module
/ Info string / absolute path to cached .info file
/ GoMod string / absolute path to cached .mod file
/ Zip string / absolute path to cached .zip file
/ Dir string / absolute path to cached source root directory
/ Sum string / checksum for path, version (as in go.sum)
/ GoModSum string / checksum for go.mod (as in go.sum)
/ Origin any / provenance of module
/ Reuse bool / reuse of old module info is safe
/ }
/
/ The -reuse flag accepts the name of file containing the JSON output of a
/ previous 'go mod download -json' invocation. The go command may use this
/ file to determine that a module is unchanged since the previous invocation
/ and avoid redownloading it. Modules that are not redownloaded will be marked
/ in the new output by setting the Reuse field to true. Normally the module
/ cache provides this kind of reuse automatically; the -reuse flag can be
/ useful on systems that do not preserve the module cache.
/
/ The -x flag causes download to print the commands download executes.
/
/ See https://golang.org/ref/mod#go-mod-download for more about 'go mod download'.
/
/ See https://golang.org/ref/mod#version-queries for more about version queries.
/
/ # Edit go.mod from tools or scripts
/
/ Usage:
/
/ go mod edit [editing flags] [-fmt|-print|-json] [go.mod]
/
/ Edit provides a command-line interface for editing go.mod,
/ for use primarily by tools or scripts. It reads only go.mod;
/ it does not look up information about the modules involved.
/ By default, edit reads and writes the go.mod file of the main module,
/ but a different target file can be specified after the editing flags.
/
/ The editing flags specify a sequence of editing operations.
/
/ The -fmt flag reformats the go.mod file without making other changes.
/ This reformatting is also implied by any other modifications that use or
/ rewrite the go.mod file. The only time this flag is needed is if no other
/ flags are specified, as in 'go mod edit -fmt'.
/
/ The -module flag changes the module's path (the go.mod file's module line).
/
/ The -require=path@version and -droprequire=path flags
/ add and drop a requirement on the given module path and version.
/ Note that -require overrides any existing requirements on path.
/ These flags are mainly for tools that understand the module graph.
/ Users should prefer 'go get path@version' or 'go get path@none',
/ which make other go.mod adjustments as needed to satisfy
/ constraints imposed by other modules.
/
/ The -exclude=path@version and -dropexclude=path@version flags
/ add and drop an exclusion for the given module path and version.
/ Note that -exclude=path@version is a no-op if that exclusion already exists.
/
/ The -replace=old[@v]=new[@v] flag adds a replacement of the given
/ module path and version pair. If the @v in old@v is omitted, a
/ replacement without a version on the left side is added, which applies
/ to all versions of the old module path. If the @v in new@v is omitted,
/ the new path should be a local module root directory, not a module
/ path. Note that -replace overrides any redundant replacements for old[@v],
/ so omitting @v will drop existing replacements for specific versions.
/
/ The -dropreplace=old[@v] flag drops a replacement of the given
/ module path and version pair. If the @v is omitted, a replacement without
/ a version on the left side is dropped.
/
/ The -retract=version and -dropretract=version flags add and drop a
/ retraction on the given version. The version may be a single version
/ like "v1.2.3" or a closed interval like "[v1.1.0,v1.1.9]". Note that
/ -retract=version is a no-op if that retraction already exists.
/
/ The -require, -droprequire, -exclude, -dropexclude, -replace,
/ -dropreplace, -retract, and -dropretract editing flags may be repeated,
/ and the changes are applied in the order given.
/
/ The -go=version flag sets the expected Go language version.
/
/ The -print flag prints the final go.mod in its text format instead of
/ writing it back to go.mod.
/
/ The -json flag prints the final go.mod file in JSON format instead of
/ writing it back to go.mod. The JSON output corresponds to these Go types:
/
/ type Module struct {
/ Path string
/ Version string
/ }
/
/ type GoMod struct {
/ Module ModPath
/ Go string
/ Require []Require
/ Exclude []Module
/ Replace []Replace
/ Retract []Retract
/ }
/
/ type ModPath struct {
/ Path string
/ Deprecated string
/ }
/
/ type Require struct {
/ Path string
/ Version string
/ Indirect bool
/ }
/
/ type Replace struct {
/ Old Module
/ New Module
/ }
/
/ type Retract struct {
/ Low string
/ High string
/ Rationale string
/ }
/
/ Retract entries representing a single version (not an interval) will have
/ the "Low" and "High" fields set to the same value.
/
/ Note that this only describes the go.mod file itself, not other modules
/ referred to indirectly. For the full set of modules available to a build,
/ use 'go list -m -json all'.
/
/ See https://golang.org/ref/mod#go-mod-edit for more about 'go mod edit'.
/
/ # Print module requirement graph
/
/ Usage:
/
/ go mod graph [-go=version]
/
/ Graph prints the module requirement graph (with replacements applied)
/ in text form. Each line in the output has two space-separated fields: a module
/ and one of its requirements. Each module is identified as a string of the form
/ path@version, except for the main module, which has no @version suffix.
/
/ The -go flag causes graph to report the module graph as loaded by the
/ given Go version, instead of the version indicated by the 'go' directive
/ in the go.mod file.
/
/ See https://golang.org/ref/mod#go-mod-graph for more about 'go mod graph'.
/
/ # Initialize new module in current directory
/
/ Usage:
/
/ go mod init [module-path]
/
/ Init initializes and writes a new go.mod file in the current directory, in
/ effect creating a new module rooted at the current directory. The go.mod file
/ must not already exist.
/
/ Init accepts one optional argument, the module path for the new module. If the
/ module path argument is omitted, init will attempt to infer the module path
/ using import comments in .go files, vendoring tool configuration files (like
/ Gopkg.lock), and the current directory (if in GOPATH).
/
/ If a configuration file for a vendoring tool is present, init will attempt to
/ import module requirements from it.
/
/ See https://golang.org/ref/mod#go-mod-init for more about 'go mod init'.
/
/ # Add missing and remove unused modules
/
/ Usage:
/
/ go mod tidy [-e] [-v] [-go=version] [-compat=version]
/
/ Tidy makes sure go.mod matches the source code in the module.
/ It adds any missing modules necessary to build the current module's
/ packages and dependencies, and it removes unused modules that
/ don't provide any relevant packages. It also adds any missing entries
/ to go.sum and removes any unnecessary ones.
/
/ The -v flag causes tidy to print information about removed modules
/ to standard error.
/
/ The -e flag causes tidy to attempt to proceed despite errors
/ encountered while loading packages.
/
/ The -go flag causes tidy to update the 'go' directive in the go.mod
/ file to the given version, which may change which module dependencies
/ are retained as explicit requirements in the go.mod file.
/ (Go versions 1.17 and higher retain more requirements in order to
/ support lazy module loading.)
/
/ The -compat flag preserves any additional checksums needed for the
/ 'go' command from the indicated major Go release to successfully load
/ the module graph, and causes tidy to error out if that version of the
/ 'go' command would load any imported package from a different module
/ version. By default, tidy acts as if the -compat flag were set to the
/ version prior to the one indicated by the 'go' directive in the go.mod
/ file.
/
/ See https://golang.org/ref/mod#go-mod-tidy for more about 'go mod tidy'.
/
/ # Make vendored copy of dependencies
/
/ Usage:
/
/ go mod vendor [-e] [-v] [-o outdir]
/
/ Vendor resets the main module's vendor directory to include all packages
/ needed to build and test all the main module's packages.
/ It does not include test code for vendored packages.
/
/ The -v flag causes vendor to print the names of vendored
/ modules and packages to standard error.
/
/ The -e flag causes vendor to attempt to proceed despite errors
/ encountered while loading packages.
/
/ The -o flag causes vendor to create the vendor directory at the given
/ path instead of "vendor". The go command can only use a vendor directory
/ named "vendor" within the module root directory, so this flag is
/ primarily useful for other tools.
/
/ See https://golang.org/ref/mod#go-mod-vendor for more about 'go mod vendor'.
/
/ # Verify dependencies have expected content
/
/ Usage:
/
/ go mod verify
/
/ Verify checks that the dependencies of the current module,
/ which are stored in a local downloaded source cache, have not been
/ modified since being downloaded. If all the modules are unmodified,
/ verify prints "all modules verified." Otherwise it reports which
/ modules have been changed and causes 'go mod' to exit with a
/ non-zero status.
/
/ See https://golang.org/ref/mod#go-mod-verify for more about 'go mod verify'.
/
/ # Explain why packages or modules are needed
/
/ Usage:
/
/ go mod why [-m] [-vendor] packages...
/
/ Why shows a shortest path in the import graph from the main module to
/ each of the listed packages. If the -m flag is given, why treats the
/ arguments as a list of modules and finds a path to any package in each
/ of the modules.
/
/ By default, why queries the graph of packages matched by "go list all",
/ which includes tests for reachable packages. The -vendor flag causes why
/ to exclude tests of dependencies.
/
/ The output is a sequence of stanzas, one for each package or module
/ name on the command line, separated by blank lines. Each stanza begins
/ with a comment line "# package" or "# module" giving the target
/ package or module. Subsequent lines give a path through the import
/ graph, one package per line. If the package or module is not
/ referenced from the main module, the stanza will display a single
/ parenthesized note indicating that fact.
/
/ For example:
/
/ $ go mod why golang.org/x/text/language golang.org/x/text/encoding
/ # golang.org/x/text/language
/ rsc.io/quote
/ rsc.io/sampler
/ golang.org/x/text/language
/
/ # golang.org/x/text/encoding
/ (main module does not need package golang.org/x/text/encoding)
/ $
/
/ See https://golang.org/ref/mod#go-mod-why for more about 'go mod why'.
/
/ # Workspace maintenance
/
/ Work provides access to operations on workspaces.
/
/ Note that support for workspaces is built into many other commands, not
/ just 'go work'.
/
/ See 'go help modules' for information about Go's module system of which
/ workspaces are a part.
/
/ See https://go.dev/ref/mod#workspaces for an in-depth reference on
/ workspaces.
/
/ See https://go.dev/doc/tutorial/workspaces for an introductory
/ tutorial on workspaces.
/
/ A workspace is specified by a go.work file that specifies a set of
/ module directories with the "use" directive. These modules are used as
/ root modules by the go command for builds and related operations. A
/ workspace that does not specify modules to be used cannot be used to do
/ builds from local modules.
/
/ go.work files are line-oriented. Each line holds a single directive,
/ made up of a keyword followed by arguments. For example:
/
/ go 1.18
/
/ use ../foo/bar
/ use ./baz
/
/ replace example.com/foo v1.2.3 => example.com/bar v1.4.5
/
/ The leading keyword can be factored out of adjacent lines to create a block,
/ like in Go imports.
/
/ use (
/ ../foo/bar
/ ./baz
/ )
/
/ The use directive specifies a module to be included in the workspace's
/ set of main modules. The argument to the use directive is the directory
/ containing the module's go.mod file.
/
/ The go directive specifies the version of Go the file was written at. It
/ is possible there may be future changes in the semantics of workspaces
/ that could be controlled by this version, but for now the version
/ specified has no effect.
/
/ The replace directive has the same syntax as the replace directive in a
/ go.mod file and takes precedence over replaces in go.mod files. It is
/ primarily intended to override conflicting replaces in different workspace
/ modules.
/
/ To determine whether the go command is operating in workspace mode, use
/ the "go env GOWORK" command. This will specify the workspace file being
/ used.
/
/ Usage:
/
/ go work <command> [arguments]
/
/ The commands are:
/
/ edit edit go.work from tools or scripts
/ init initialize workspace file
/ sync sync workspace build list to modules
/ use add modules to workspace file
/
/ Use "go help work <command>" for more information about a command.
/
/ # Edit go.work from tools or scripts
/
/ Usage:
/
/ go work edit [editing flags] [go.work]
/
/ Edit provides a command-line interface for editing go.work,
/ for use primarily by tools or scripts. It only reads go.work;
/ it does not look up information about the modules involved.
/ If no file is specified, Edit looks for a go.work file in the current
/ directory and its parent directories
/
/ The editing flags specify a sequence of editing operations.
/
/ The -fmt flag reformats the go.work file without making other changes.
/ This reformatting is also implied by any other modifications that use or
/ rewrite the go.mod file. The only time this flag is needed is if no other
/ flags are specified, as in 'go work edit -fmt'.
/
/ The -use=path and -dropuse=path flags
/ add and drop a use directive from the go.work file's set of module directories.
/
/ The -replace=old[@v]=new[@v] flag adds a replacement of the given
/ module path and version pair. If the @v in old@v is omitted, a
/ replacement without a version on the left side is added, which applies
/ to all versions of the old module path. If the @v in new@v is omitted,
/ the new path should be a local module root directory, not a module
/ path. Note that -replace overrides any redundant replacements for old[@v],
/ so omitting @v will drop existing replacements for specific versions.
/
/ The -dropreplace=old[@v] flag drops a replacement of the given
/ module path and version pair. If the @v is omitted, a replacement without
/ a version on the left side is dropped.
/
/ The -use, -dropuse, -replace, and -dropreplace,
/ editing flags may be repeated, and the changes are applied in the order given.
/
/ The -go=version flag sets the expected Go language version.
/
/ The -print flag prints the final go.work in its text format instead of
/ writing it back to go.mod.
/
/ The -json flag prints the final go.work file in JSON format instead of
/ writing it back to go.mod. The JSON output corresponds to these Go types:
/
/ type GoWork struct {
/ Go string
/ Use []Use
/ Replace []Replace
/ }
/
/ type Use struct {
/ DiskPath string
/ ModulePath string
/ }
/
/ type Replace struct {
/ Old Module
/ New Module
/ }
/
/ type Module struct {
/ Path string
/ Version string
/ }
/
/ See the workspaces reference at https://go.dev/ref/mod#workspaces
/ for more information.
/
/ # Initialize workspace file
/
/ Usage:
/
/ go work init [moddirs]
/
/ Init initializes and writes a new go.work file in the
/ current directory, in effect creating a new workspace at the current
/ directory.
/
/ go work init optionally accepts paths to the workspace modules as
/ arguments. If the argument is omitted, an empty workspace with no
/ modules will be created.
/
/ Each argument path is added to a use directive in the go.work file. The
/ current go version will also be listed in the go.work file.
/
/ See the workspaces reference at https://go.dev/ref/mod#workspaces
/ for more information.
/
/ # Sync workspace build list to modules
/
/ Usage:
/
/ go work sync
/
/ Sync syncs the workspace's build list back to the
/ workspace's modules
/
/ The workspace's build list is the set of versions of all the
/ (transitive) dependency modules used to do builds in the workspace. go
/ work sync generates that build list using the Minimal Version Selection
/ algorithm, and then syncs those versions back to each of modules
/ specified in the workspace (with use directives).
/
/ The syncing is done by sequentially upgrading each of the dependency
/ modules specified in a workspace module to the version in the build list
/ if the dependency module's version is not already the same as the build
/ list's version. Note that Minimal Version Selection guarantees that the
/ build list's version of each module is always the same or higher than
/ that in each workspace module.
/
/ See the workspaces reference at https://go.dev/ref/mod#workspaces
/ for more information.
/
/ # Add modules to workspace file
/
/ Usage:
/
/ go work use [-r] moddirs
/
/ Use provides a command-line interface for adding
/ directories, optionally recursively, to a go.work file.
/
/ A use directive will be added to the go.work file for each argument
/ directory listed on the command line go.work file, if it exists on disk,
/ or removed from the go.work file if it does not exist on disk.
/
/ The -r flag searches recursively for modules in the argument
/ directories, and the use command operates as if each of the directories
/ were specified as arguments: namely, use directives will be added for
/ directories that exist, and removed for directories that do not exist.
/
/ See the workspaces reference at https://go.dev/ref/mod#workspaces
/ for more information.
/
/ # Compile and run Go program
/
/ Usage:
/
/ go run [build flags] [-exec xprog] package [arguments...]
/
/ Run compiles and runs the named main Go package.
/ Typically the package is specified as a list of .go source files from a single
/ directory, but it may also be an import path, file system path, or pattern
/ matching a single known package, as in 'go run .' or 'go run my/cmd'.
/
/ If the package argument has a version suffix (like @latest or @v1.0.0),
/ "go run" builds the program in module-aware mode, ignoring the go.mod file in
/ the current directory or any parent directory, if there is one. This is useful
/ for running programs without affecting the dependencies of the main module.
/
/ If the package argument doesn't have a version suffix, "go run" may run in
/ module-aware mode or GOPATH mode, depending on the GO111MODULE environment
/ variable and the presence of a go.mod file. See 'go help modules' for details.
/ If module-aware mode is enabled, "go run" runs in the context of the main
/ module.
/
/ By default, 'go run' runs the compiled binary directly: 'a.out arguments...'.
/ If the -exec flag is given, 'go run' invokes the binary using xprog:
/
/ 'xprog a.out arguments...'.
/
/ If the -exec flag is not given, GOOS or GOARCH is different from the system
/ default, and a program named go_$GOOS_$GOARCH_exec can be found
/ on the current search path, 'go run' invokes the binary using that program,
/ for example 'go_js_wasm_exec a.out arguments...'. This allows execution of
/ cross-compiled programs when a simulator or other execution method is
/ available.
/
/ By default, 'go run' compiles the binary without generating the information
/ used by debuggers, to reduce build time. To include debugger information in
/ the binary, use 'go build'.
/
/ The exit status of Run is not the exit status of the compiled binary.
/
/ For more about build flags, see 'go help build'.
/ For more about specifying packages, see 'go help packages'.
/
/ See also: go build.
/
/ # Test packages
/
/ Usage:
/
/ go test [build/test flags] [packages] [build/test flags & test binary flags]
/
/ 'Go test' automates testing the packages named by the import paths.
/ It prints a summary of the test results in the format:
/
/ ok archive/tar 0.011s
/ FAIL archive/zip 0.022s
/ ok compress/gzip 0.033s
/ ...
/
/ followed by detailed output for each failed package.
/
/ 'Go test' recompiles each package along with any files with names matching
/ the file pattern "*_test.go".
/ These additional files can contain test functions, benchmark functions, fuzz
/ tests and example functions. See 'go help testfunc' for more.
/ Each listed package causes the execution of a separate test binary.
/ Files whose names begin with "_" (including "_test.go") or "." are ignored.
/
/ Test files that declare a package with the suffix "_test" will be compiled as a
/ separate package, and then linked and run with the main test binary.
/
/ The go tool will ignore a directory named "testdata", making it available
/ to hold ancillary data needed by the tests.
/
/ As part of building a test binary, go test runs go vet on the package
/ and its test source files to identify significant problems. If go vet
/ finds any problems, go test reports those and does not run the test
/ binary. Only a high-confidence subset of the default go vet checks are
/ used. That subset is: 'atomic', 'bool', 'buildtags', 'errorsas',
/ 'ifaceassert', 'nilfunc', 'printf', and 'stringintconv'. You can see
/ the documentation for these and other vet tests via "go doc cmd/vet".
/ To disable the running of go vet, use the -vet=off flag. To run all
/ checks, use the -vet=all flag.
/
/ All test output and summary lines are printed to the go command's
/ standard output, even if the test printed them to its own standard
/ error. (The go command's standard error is reserved for printing
/ errors building the tests.)
/
/ Go test runs in two different modes:
/
/ The first, called local directory mode, occurs when go test is
/ invoked with no package arguments (for example, 'go test' or 'go
/ test -v'). In this mode, go test compiles the package sources and
/ tests found in the current directory and then runs the resulting
/ test binary. In this mode, caching (discussed below) is disabled.
/ After the package test finishes, go test prints a summary line
/ showing the test status ('ok' or 'FAIL'), package name, and elapsed
/ time.
/
/ The second, called package list mode, occurs when go test is invoked
/ with explicit package arguments (for example 'go test math', 'go
/ test ./...', and even 'go test .'). In this mode, go test compiles
/ and tests each of the packages listed on the command line. If a
/ package test passes, go test prints only the final 'ok' summary
/ line. If a package test fails, go test prints the full test output.
/ If invoked with the -bench or -v flag, go test prints the full
/ output even for passing package tests, in order to display the
/ requested benchmark results or verbose logging. After the package
/ tests for all of the listed packages finish, and their output is
/ printed, go test prints a final 'FAIL' status if any package test
/ has failed.
/
/ In package list mode only, go test caches successful package test
/ results to avoid unnecessary repeated running of tests. When the
/ result of a test can be recovered from the cache, go test will
/ redisplay the previous output instead of running the test binary
/ again. When this happens, go test prints '(cached)' in place of the
/ elapsed time in the summary line.
/
/ The rule for a match in the cache is that the run involves the same
/ test binary and the flags on the command line come entirely from a
/ restricted set of 'cacheable' test flags, defined as -benchtime, -cpu,
/ -list, -parallel, -run, -short, -timeout, -failfast, and -v.
/ If a run of go test has any test or non-test flags outside this set,
/ the result is not cached. To disable test caching, use any test flag
/ or argument other than the cacheable flags. The idiomatic way to disable
/ test caching explicitly is to use -count=1. Tests that open files within
/ the package's source root (usually $GOPATH) or that consult environment
/ variables only match future runs in which the files and environment
/ variables are unchanged. A cached test result is treated as executing
/ in no time at all, so a successful package test result will be cached and
/ reused regardless of -timeout setting.
/
/ In addition to the build flags, the flags handled by 'go test' itself are:
/
/ -args
/ Pass the remainder of the command line (everything after -args)
/ to the test binary, uninterpreted and unchanged.
/ Because this flag consumes the remainder of the command line,
/ the package list (if present) must appear before this flag.
/
/ -c
/ Compile the test binary to pkg.test but do not run it
/ (where pkg is the last element of the package's import path).
/ The file name can be changed with the -o flag.
/
/ -exec xprog
/ Run the test binary using xprog. The behavior is the same as
/ in 'go run'. See 'go help run' for details.
/
/ -i
/ Install packages that are dependencies of the test.
/ Do not run the test.
/ The -i flag is deprecated. Compiled packages are cached automatically.
/
/ -json
/ Convert test output to JSON suitable for automated processing.
/ See 'go doc test2json' for the encoding details.
/
/ -o file
/ Compile the test binary to the named file.
/ The test still runs (unless -c or -i is specified).
/
/ The test binary also accepts flags that control execution of the test; these
/ flags are also accessible by 'go test'. See 'go help testflag' for details.
/
/ For more about build flags, see 'go help build'.
/ For more about specifying packages, see 'go help packages'.
/
/ See also: go build, go vet.
/
/ # Run specified go tool
/
/ Usage:
/
/ go tool [-n] command [args...]
/
/ Tool runs the go tool command identified by the arguments.
/ With no arguments it prints the list of known tools.
/
/ The -n flag causes tool to print the command that would be
/ executed but not execute it.
/
/ For more about each tool command, see 'go doc cmd/<command>'.
/
/ # Print Go version
/
/ Usage:
/
/ go version [-m] [-v] [file ...]
/
/ Version prints the build information for Go executables.
/
/ Go version reports the Go version used to build each of the named
/ executable files.
/
/ If no files are named on the command line, go version prints its own
/ version information.
/
/ If a directory is named, go version walks that directory, recursively,
/ looking for recognized Go binaries and reporting their versions.
/ By default, go version does not report unrecognized files found
/ during a directory scan. The -v flag causes it to report unrecognized files.
/
/ The -m flag causes go version to print each executable's embedded
/ module version information, when available. In the output, the module
/ information consists of multiple lines following the version line, each
/ indented by a leading tab character.
/
/ See also: go doc runtime/debug.BuildInfo.
/
/ # Report likely mistakes in packages
/
/ Usage:
/
/ go vet [-n] [-x] [-vettool prog] [build flags] [vet flags] [packages]
/
/ Vet runs the Go vet command on the packages named by the import paths.
/
/ For more about vet and its flags, see 'go doc cmd/vet'.
/ For more about specifying packages, see 'go help packages'.
/ For a list of checkers and their flags, see 'go tool vet help'.
/ For details of a specific checker such as 'printf', see 'go tool vet help printf'.
/
/ The -n flag prints commands that would be executed.
/ The -x flag prints commands as they are executed.
/
/ The -vettool=prog flag selects a different analysis tool with alternative
/ or additional checks.
/ For example, the 'shadow' analyzer can be built and run using these commands:
/
/ go install golang.org/x/tools/go/analysis/passes/shadow/cmd/shadow
/ go vet -vettool=$(which shadow)
/
/ The build flags supported by go vet are those that control package resolution
/ and execution, such as -n, -x, -v, -tags, and -toolexec.
/ For more about these flags, see 'go help build'.
/
/ See also: go fmt, go fix.
/
/ # Build constraints
/
/ A build constraint, also known as a build tag, is a condition under which a
/ file should be included in the package. Build constraints are given by a
/ line comment that begins
/
/ /go:build
/
/ Constraints may appear in any kind of source file (not just Go), but
/ they must appear near the top of the file, preceded
/ only by blank lines and other line comments. These rules mean that in Go
/ files a build constraint must appear before the package clause.
/
/ To distinguish build constraints from package documentation,
/ a build constraint should be followed by a blank line.
/
/ A build constraint comment is evaluated as an expression containing
/ build tags combined by ||, &&, and ! operators and parentheses.
/ Operators have the same meaning as in Go.
/
/ For example, the following build constraint constrains a file to
/ build when the "linux" and "386" constraints are satisfied, or when
/ "darwin" is satisfied and "cgo" is not:
/
/ /go:build (linux && 386) || (darwin && !cgo)
/
/ It is an error for a file to have more than one /go:build line.
/
/ During a particular build, the following build tags are satisfied:
/
/ - the target operating system, as spelled by runtime.GOOS, set with the
/ GOOS environment variable.
/ - the target architecture, as spelled by runtime.GOARCH, set with the
/ GOARCH environment variable.
/ - "unix", if GOOS is a Unix or Unix-like system.
/ - the compiler being used, either "gc" or "gccgo"
/ - "cgo", if the cgo command is supported (see CGO_ENABLED in
/ 'go help environment').
/ - a term for each Go major release, through the current version:
/ "go1.1" from Go version 1.1 onward, "go1.12" from Go 1.12, and so on.
/ - any additional tags given by the -tags flag (see 'go help build').
/
/ There are no separate build tags for beta or minor releases.
/
/ If a file's name, after stripping the extension and a possible _test suffix,
/ matches any of the following patterns:
/
/ *_GOOS
/ *_GOARCH
/ *_GOOS_GOARCH
/
/ (example: source_windows_amd64.go) where GOOS and GOARCH represent
/ any known operating system and architecture values respectively, then
/ the file is considered to have an implicit build constraint requiring
/ those terms (in addition to any explicit constraints in the file).
/
/ Using GOOS=android matches build tags and files as for GOOS=linux
/ in addition to android tags and files.
/
/ Using GOOS=illumos matches build tags and files as for GOOS=solaris
/ in addition to illumos tags and files.
/
/ Using GOOS=ios matches build tags and files as for GOOS=darwin
/ in addition to ios tags and files.
/
/ To keep a file from being considered for the build:
/
/ /go:build ignore
/
/ (any other unsatisfied word will work as well, but "ignore" is conventional.)
/
/ To build a file only when using cgo, and only on Linux and OS X:
/
/ /go:build cgo && (linux || darwin)
/
/ Such a file is usually paired with another file implementing the
/ default functionality for other systems, which in this case would
/ carry the constraint:
/
/ /go:build !(cgo && (linux || darwin))
/
/ Naming a file dns_windows.go will cause it to be included only when
/ building the package for Windows; similarly, math_386.s will be included
/ only when building the package for 32-bit x86.
/
/ Go versions 1.16 and earlier used a different syntax for build constraints,
/ with a "/ +build" prefix. The gofmt command will add an equivalent /go:build
/ constraint when encountering the older syntax.
/
/ # Build modes
/
/ The 'go build' and 'go install' commands take a -buildmode argument which
/ indicates which kind of object file is to be built. Currently supported values
/ are:
/
/ -buildmode=archive
/ Build the listed non-main packages into .a files. Packages named
/ main are ignored.
/
/ -buildmode=c-archive
/ Build the listed main package, plus all packages it imports,
/ into a C archive file. The only callable symbols will be those
/ functions exported using a cgo /export comment. Requires
/ exactly one main package to be listed.
/
/ -buildmode=c-shared
/ Build the listed main package, plus all packages it imports,
/ into a C shared library. The only callable symbols will
/ be those functions exported using a cgo /export comment.
/ Requires exactly one main package to be listed.
/
/ -buildmode=default
/ Listed main packages are built into executables and listed
/ non-main packages are built into .a files (the default
/ behavior).
/
/ -buildmode=shared
/ Combine all the listed non-main packages into a single shared
/ library that will be used when building with the -linkshared
/ option. Packages named main are ignored.
/
/ -buildmode=exe
/ Build the listed main packages and everything they import into
/ executables. Packages not named main are ignored.
/
/ -buildmode=pie
/ Build the listed main packages and everything they import into
/ position independent executables (PIE). Packages not named
/ main are ignored.
/
/ -buildmode=plugin
/ Build the listed main packages, plus all packages that they
/ import, into a Go plugin. Packages not named main are ignored.
/
/ On AIX, when linking a C program that uses a Go archive built with
/ -buildmode=c-archive, you must pass -Wl,-bnoobjreorder to the C compiler.
/
/ # Calling between Go and C
/
/ There are two different ways to call between Go and C/C++ code.
/
/ The first is the cgo tool, which is part of the Go distribution. For
/ information on how to use it see the cgo documentation (go doc cmd/cgo).
/
/ The second is the SWIG program, which is a general tool for
/ interfacing between languages. For information on SWIG see
/ http://swig.org/. When running go build, any file with a .swig
/ extension will be passed to SWIG. Any file with a .swigcxx extension
/ will be passed to SWIG with the -c++ option.
/
/ When either cgo or SWIG is used, go build will pass any .c, .m, .s, .S
/ or .sx files to the C compiler, and any .cc, .cpp, .cxx files to the C++
/ compiler. The CC or CXX environment variables may be set to determine
/ the C or C++ compiler, respectively, to use.
/
/ # Build and test caching
/
/ The go command caches build outputs for reuse in future builds.
/ The default location for cache data is a subdirectory named go-build
/ in the standard user cache directory for the current operating system.
/ Setting the GOCACHE environment variable overrides this default,
/ and running 'go env GOCACHE' prints the current cache directory.
/
/ The go command periodically deletes cached data that has not been
/ used recently. Running 'go clean -cache' deletes all cached data.
/
/ The build cache correctly accounts for changes to Go source files,
/ compilers, compiler options, and so on: cleaning the cache explicitly
/ should not be necessary in typical use. However, the build cache
/ does not detect changes to C libraries imported with cgo.
/ If you have made changes to the C libraries on your system, you
/ will need to clean the cache explicitly or else use the -a build flag
/ (see 'go help build') to force rebuilding of packages that
/ depend on the updated C libraries.
/
/ The go command also caches successful package test results.
/ See 'go help test' for details. Running 'go clean -testcache' removes
/ all cached test results (but not cached build results).
/
/ The go command also caches values used in fuzzing with 'go test -fuzz',
/ specifically, values that expanded code coverage when passed to a
/ fuzz function. These values are not used for regular building and
/ testing, but they're stored in a subdirectory of the build cache.
/ Running 'go clean -fuzzcache' removes all cached fuzzing values.
/ This may make fuzzing less effective, temporarily.
/
/ The GODEBUG environment variable can enable printing of debugging
/ information about the state of the cache:
/
/ GODEBUG=gocacheverify=1 causes the go command to bypass the
/ use of any cache entries and instead rebuild everything and check
/ that the results match existing cache entries.
/
/ GODEBUG=gocachehash=1 causes the go command to print the inputs
/ for all of the content hashes it uses to construct cache lookup keys.
/ The output is voluminous but can be useful for debugging the cache.
/
/ GODEBUG=gocachetest=1 causes the go command to print details of its
/ decisions about whether to reuse a cached test result.
/
/ # Environment variables
/
/ The go command and the tools it invokes consult environment variables
/ for configuration. If an environment variable is unset, the go command
/ uses a sensible default setting. To see the effective setting of the
/ variable <NAME>, run 'go env <NAME>'. To change the default setting,
/ run 'go env -w <NAME>=<VALUE>'. Defaults changed using 'go env -w'
/ are recorded in a Go environment configuration file stored in the
/ per-user configuration directory, as reported by os.UserConfigDir.
/ The location of the configuration file can be changed by setting
/ the environment variable GOENV, and 'go env GOENV' prints the
/ effective location, but 'go env -w' cannot change the default location.
/ See 'go help env' for details.
/
/ General-purpose environment variables:
/
/ GO111MODULE
/ Controls whether the go command runs in module-aware mode or GOPATH mode.
/ May be "off", "on", or "auto".
/ See https://golang.org/ref/mod#mod-commands.
/ GCCGO
/ The gccgo command to run for 'go build -compiler=gccgo'.
/ GOARCH
/ The architecture, or processor, for which to compile code.
/ Examples are amd64, 386, arm, ppc64.
/ GOBIN
/ The directory where 'go install' will install a command.
/ GOCACHE
/ The directory where the go command will store cached
/ information for reuse in future builds.
/ GOMODCACHE
/ The directory where the go command will store downloaded modules.
/ GODEBUG
/ Enable various debugging facilities. See 'go doc runtime'
/ for details.
/ GOENV
/ The location of the Go environment configuration file.
/ Cannot be set using 'go env -w'.
/ Setting GOENV=off in the environment disables the use of the
/ default configuration file.
/ GOFLAGS
/ A space-separated list of -flag=value settings to apply
/ to go commands by default, when the given flag is known by
/ the current command. Each entry must be a standalone flag.
/ Because the entries are space-separated, flag values must
/ not contain spaces. Flags listed on the command line
/ are applied after this list and therefore override it.
/ GOINSECURE
/ Comma-separated list of glob patterns (in the syntax of Go's path.Match)
/ of module path prefixes that should always be fetched in an insecure
/ manner. Only applies to dependencies that are being fetched directly.
/ GOINSECURE does not disable checksum database validation. GOPRIVATE or
/ GONOSUMDB may be used to achieve that.
/ GOOS
/ The operating system for which to compile code.
/ Examples are linux, darwin, windows, netbsd.
/ GOPATH
/ For more details see: 'go help gopath'.
/ GOPROXY
/ URL of Go module proxy. See https://golang.org/ref/mod#environment-variables
/ and https://golang.org/ref/mod#module-proxy for details.
/ GOPRIVATE, GONOPROXY, GONOSUMDB
/ Comma-separated list of glob patterns (in the syntax of Go's path.Match)
/ of module path prefixes that should always be fetched directly
/ or that should not be compared against the checksum database.
/ See https://golang.org/ref/mod#private-modules.
/ GOROOT
/ The root of the go tree.
/ GOSUMDB
/ The name of checksum database to use and optionally its public key and
/ URL. See https://golang.org/ref/mod#authenticating.
/ GOTMPDIR
/ The directory where the go command will write
/ temporary source files, packages, and binaries.
/ GOVCS
/ Lists version control commands that may be used with matching servers.
/ See 'go help vcs'.
/ GOWORK
/ In module aware mode, use the given go.work file as a workspace file.
/ By default or when GOWORK is "auto", the go command searches for a
/ file named go.work in the current directory and then containing directories
/ until one is found. If a valid go.work file is found, the modules
/ specified will collectively be used as the main modules. If GOWORK
/ is "off", or a go.work file is not found in "auto" mode, workspace
/ mode is disabled.
/
/ Environment variables for use with cgo:
/
/ AR
/ The command to use to manipulate library archives when
/ building with the gccgo compiler.
/ The default is 'ar'.
/ CC
/ The command to use to compile C code.
/ CGO_ENABLED
/ Whether the cgo command is supported. Either 0 or 1.
/ CGO_CFLAGS
/ Flags that cgo will pass to the compiler when compiling
/ C code.
/ CGO_CFLAGS_ALLOW
/ A regular expression specifying additional flags to allow
/ to appear in #cgo CFLAGS source code directives.
/ Does not apply to the CGO_CFLAGS environment variable.
/ CGO_CFLAGS_DISALLOW
/ A regular expression specifying flags that must be disallowed
/ from appearing in #cgo CFLAGS source code directives.
/ Does not apply to the CGO_CFLAGS environment variable.
/ CGO_CPPFLAGS, CGO_CPPFLAGS_ALLOW, CGO_CPPFLAGS_DISALLOW
/ Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
/ but for the C preprocessor.
/ CGO_CXXFLAGS, CGO_CXXFLAGS_ALLOW, CGO_CXXFLAGS_DISALLOW
/ Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
/ but for the C++ compiler.
/ CGO_FFLAGS, CGO_FFLAGS_ALLOW, CGO_FFLAGS_DISALLOW
/ Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
/ but for the Fortran compiler.
/ CGO_LDFLAGS, CGO_LDFLAGS_ALLOW, CGO_LDFLAGS_DISALLOW
/ Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
/ but for the linker.
/ CXX
/ The command to use to compile C++ code.
/ FC
/ The command to use to compile Fortran code.
/ PKG_CONFIG
/ Path to pkg-config tool.
/
/ Architecture-specific environment variables:
/
/ GOARM
/ For GOARCH=arm, the ARM architecture for which to compile.
/ Valid values are 5, 6, 7.
/ GO386
/ For GOARCH=386, how to implement floating point instructions.
/ Valid values are sse2 (default), softfloat.
/ GOAMD64
/ For GOARCH=amd64, the microarchitecture level for which to compile.
/ Valid values are v1 (default), v2, v3, v4.
/ See https://golang.org/wiki/MinimumRequirements#amd64
/ GOMIPS
/ For GOARCH=mips{,le}, whether to use floating point instructions.
/ Valid values are hardfloat (default), softfloat.
/ GOMIPS64
/ For GOARCH=mips64{,le}, whether to use floating point instructions.
/ Valid values are hardfloat (default), softfloat.
/ GOPPC64
/ For GOARCH=ppc64{,le}, the target ISA (Instruction Set Architecture).
/ Valid values are power8 (default), power9.
/ GOWASM
/ For GOARCH=wasm, comma-separated list of experimental WebAssembly features to use.
/ Valid values are satconv, signext.
/
/ Special-purpose environment variables:
/
/ GCCGOTOOLDIR
/ If set, where to find gccgo tools, such as cgo.
/ The default is based on how gccgo was configured.
/ GOEXPERIMENT
/ Comma-separated list of toolchain experiments to enable or disable.
/ The list of available experiments may change arbitrarily over time.
/ See src/internal/goexperiment/flags.go for currently valid values.
/ Warning: This variable is provided for the development and testing
/ of the Go toolchain itself. Use beyond that purpose is unsupported.
/ GOROOT_FINAL
/ The root of the installed Go tree, when it is
/ installed in a location other than where it is built.
/ File names in stack traces are rewritten from GOROOT to
/ GOROOT_FINAL.
/ GO_EXTLINK_ENABLED
/ Whether the linker should use external linking mode
/ when using -linkmode=auto with code that uses cgo.
/ Set to 0 to disable external linking mode, 1 to enable it.
/ GIT_ALLOW_PROTOCOL
/ Defined by Git. A colon-separated list of schemes that are allowed
/ to be used with git fetch/clone. If set, any scheme not explicitly
/ mentioned will be considered insecure by 'go get'.
/ Because the variable is defined by Git, the default value cannot
/ be set using 'go env -w'.
/
/ Additional information available from 'go env' but not read from the environment:
/
/ GOEXE
/ The executable file name suffix (".exe" on Windows, "" on other systems).
/ GOGCCFLAGS
/ A space-separated list of arguments supplied to the CC command.
/ GOHOSTARCH
/ The architecture (GOARCH) of the Go toolchain binaries.
/ GOHOSTOS
/ The operating system (GOOS) of the Go toolchain binaries.
/ GOMOD
/ The absolute path to the go.mod of the main module.
/ If module-aware mode is enabled, but there is no go.mod, GOMOD will be
/ os.DevNull ("/dev/null" on Unix-like systems, "NUL" on Windows).
/ If module-aware mode is disabled, GOMOD will be the empty string.
/ GOTOOLDIR
/ The directory where the go tools (compile, cover, doc, etc...) are installed.
/ GOVERSION
/ The version of the installed Go tree, as reported by runtime.Version.
/
/ # File types
/
/ The go command examines the contents of a restricted set of files
/ in each directory. It identifies which files to examine based on
/ the extension of the file name. These extensions are:
/
/ .go
/ Go source files.
/ .c, .h
/ C source files.
/ If the package uses cgo or SWIG, these will be compiled with the
/ OS-native compiler (typically gcc); otherwise they will
/ trigger an error.
/ .cc, .cpp, .cxx, .hh, .hpp, .hxx
/ C++ source files. Only useful with cgo or SWIG, and always
/ compiled with the OS-native compiler.
/ .m
/ Objective-C source files. Only useful with cgo, and always
/ compiled with the OS-native compiler.
/ .s, .S, .sx
/ Assembler source files.
/ If the package uses cgo or SWIG, these will be assembled with the
/ OS-native assembler (typically gcc (sic)); otherwise they
/ will be assembled with the Go assembler.
/ .swig, .swigcxx
/ SWIG definition files.
/ .syso
/ System object files.
/
/ Files of each of these types except .syso may contain build
/ constraints, but the go command stops scanning for build constraints
/ at the first item in the file that is not a blank line or /-style
/ line comment. See the go/build package documentation for
/ more details.
/
/ # The go.mod file
/
/ A module version is defined by a tree of source files, with a go.mod
/ file in its root. When the go command is run, it looks in the current
/ directory and then successive parent directories to find the go.mod
/ marking the root of the main (current) module.
/
/ The go.mod file format is described in detail at
/ https://golang.org/ref/mod#go-mod-file.
/
/ To create a new go.mod file, use 'go mod init'. For details see
/ 'go help mod init' or https://golang.org/ref/mod#go-mod-init.
/
/ To add missing module requirements or remove unneeded requirements,
/ use 'go mod tidy'. For details, see 'go help mod tidy' or
/ https://golang.org/ref/mod#go-mod-tidy.
/
/ To add, upgrade, downgrade, or remove a specific module requirement, use
/ 'go get'. For details, see 'go help module-get' or
/ https://golang.org/ref/mod#go-get.
/
/ To make other changes or to parse go.mod as JSON for use by other tools,
/ use 'go mod edit'. See 'go help mod edit' or
/ https://golang.org/ref/mod#go-mod-edit.
/
/ # GOPATH environment variable
/
/ The Go path is used to resolve import statements.
/ It is implemented by and documented in the go/build package.
/
/ The GOPATH environment variable lists places to look for Go code.
/ On Unix, the value is a colon-separated string.
/ On Windows, the value is a semicolon-separated string.
/ On Plan 9, the value is a list.
/
/ If the environment variable is unset, GOPATH defaults
/ to a subdirectory named "go" in the user's home directory
/ ($HOME/go on Unix, %USERPROFILE%\go on Windows),
/ unless that directory holds a Go distribution.
/ Run "go env GOPATH" to see the current GOPATH.
/
/ See https://golang.org/wiki/SettingGOPATH to set a custom GOPATH.
/
/ Each directory listed in GOPATH must have a prescribed structure:
/
/ The src directory holds source code. The path below src
/ determines the import path or executable name.
/
/ The pkg directory holds installed package objects.
/ As in the Go tree, each target operating system and
/ architecture pair has its own subdirectory of pkg
/ (pkg/GOOS_GOARCH).
/
/ If DIR is a directory listed in the GOPATH, a package with
/ source in DIR/src/foo/bar can be imported as "foo/bar" and
/ has its compiled form installed to "DIR/pkg/GOOS_GOARCH/foo/bar.a".
/
/ The bin directory holds compiled commands.
/ Each command is named for its source directory, but only
/ the final element, not the entire path. That is, the
/ command with source in DIR/src/foo/quux is installed into
/ DIR/bin/quux, not DIR/bin/foo/quux. The "foo/" prefix is stripped
/ so that you can add DIR/bin to your PATH to get at the
/ installed commands. If the GOBIN environment variable is
/ set, commands are installed to the directory it names instead
/ of DIR/bin. GOBIN must be an absolute path.
/
/ Here's an example directory layout:
/
/ GOPATH=/home/user/go
/
/ /home/user/go/
/ src/
/ foo/
/ bar/ (go code in package bar)
/ x.go
/ quux/ (go code in package main)
/ y.go
/ bin/
/ quux (installed command)
/ pkg/
/ linux_amd64/
/ foo/
/ bar.a (installed package object)
/
/ Go searches each directory listed in GOPATH to find source code,
/ but new packages are always downloaded into the first directory
/ in the list.
/
/ See https://golang.org/doc/code.html for an example.
/
/ # GOPATH and Modules
/
/ When using modules, GOPATH is no longer used for resolving imports.
/ However, it is still used to store downloaded source code (in GOPATH/pkg/mod)
/ and compiled commands (in GOPATH/bin).
/
/ # Internal Directories
/
/ Code in or below a directory named "internal" is importable only
/ by code in the directory tree rooted at the parent of "internal".
/ Here's an extended version of the directory layout above:
/
/ /home/user/go/
/ src/
/ crash/
/ bang/ (go code in package bang)
/ b.go
/ foo/ (go code in package foo)
/ f.go
/ bar/ (go code in package bar)
/ x.go
/ internal/
/ baz/ (go code in package baz)
/ z.go
/ quux/ (go code in package main)
/ y.go
/
/ The code in z.go is imported as "foo/internal/baz", but that
/ import statement can only appear in source files in the subtree
/ rooted at foo. The source files foo/f.go, foo/bar/x.go, and
/ foo/quux/y.go can all import "foo/internal/baz", but the source file
/ crash/bang/b.go cannot.
/
/ See https://golang.org/s/go14internal for details.
/
/ # Vendor Directories
/
/ Go 1.6 includes support for using local copies of external dependencies
/ to satisfy imports of those dependencies, often referred to as vendoring.
/
/ Code below a directory named "vendor" is importable only
/ by code in the directory tree rooted at the parent of "vendor",
/ and only using an import path that omits the prefix up to and
/ including the vendor element.
/
/ Here's the example from the previous section,
/ but with the "internal" directory renamed to "vendor"
/ and a new foo/vendor/crash/bang directory added:
/
/ /home/user/go/
/ src/
/ crash/
/ bang/ (go code in package bang)
/ b.go
/ foo/ (go code in package foo)
/ f.go
/ bar/ (go code in package bar)
/ x.go
/ vendor/
/ crash/
/ bang/ (go code in package bang)
/ b.go
/ baz/ (go code in package baz)
/ z.go
/ quux/ (go code in package main)
/ y.go
/
/ The same visibility rules apply as for internal, but the code
/ in z.go is imported as "baz", not as "foo/vendor/baz".
/
/ Code in vendor directories deeper in the source tree shadows
/ code in higher directories. Within the subtree rooted at foo, an import
/ of "crash/bang" resolves to "foo/vendor/crash/bang", not the
/ top-level "crash/bang".
/
/ Code in vendor directories is not subject to import path
/ checking (see 'go help importpath').
/
/ When 'go get' checks out or updates a git repository, it now also
/ updates submodules.
/
/ Vendor directories do not affect the placement of new repositories
/ being checked out for the first time by 'go get': those are always
/ placed in the main GOPATH, never in a vendor subtree.
/
/ See https://golang.org/s/go15vendor for details.
/
/ # Legacy GOPATH go get
/
/ The 'go get' command changes behavior depending on whether the
/ go command is running in module-aware mode or legacy GOPATH mode.
/ This help text, accessible as 'go help gopath-get' even in module-aware mode,
/ describes 'go get' as it operates in legacy GOPATH mode.
/
/ Usage: go get [-d] [-f] [-t] [-u] [-v] [-fix] [build flags] [packages]
/
/ Get downloads the packages named by the import paths, along with their
/ dependencies. It then installs the named packages, like 'go install'.
/
/ The -d flag instructs get to stop after downloading the packages; that is,
/ it instructs get not to install the packages.
/
/ The -f flag, valid only when -u is set, forces get -u not to verify that
/ each package has been checked out from the source control repository
/ implied by its import path. This can be useful if the source is a local fork
/ of the original.
/
/ The -fix flag instructs get to run the fix tool on the downloaded packages
/ before resolving dependencies or building the code.
/
/ The -t flag instructs get to also download the packages required to build
/ the tests for the specified packages.
/
/ The -u flag instructs get to use the network to update the named packages
/ and their dependencies. By default, get uses the network to check out
/ missing packages but does not use it to look for updates to existing packages.
/
/ The -v flag enables verbose progress and debug output.
/
/ Get also accepts build flags to control the installation. See 'go help build'.
/
/ When checking out a new package, get creates the target directory
/ GOPATH/src/<import-path>. If the GOPATH contains multiple entries,
/ get uses the first one. For more details see: 'go help gopath'.
/
/ When checking out or updating a package, get looks for a branch or tag
/ that matches the locally installed version of Go. The most important
/ rule is that if the local installation is running version "go1", get
/ searches for a branch or tag named "go1". If no such version exists
/ it retrieves the default branch of the package.
/
/ When go get checks out or updates a Git repository,
/ it also updates any git submodules referenced by the repository.
/
/ Get never checks out or updates code stored in vendor directories.
/
/ For more about specifying packages, see 'go help packages'.
/
/ For more about how 'go get' finds source code to
/ download, see 'go help importpath'.
/
/ This text describes the behavior of get when using GOPATH
/ to manage source code and dependencies.
/ If instead the go command is running in module-aware mode,
/ the details of get's flags and effects change, as does 'go help get'.
/ See 'go help modules' and 'go help module-get'.
/
/ See also: go build, go install, go clean.
/
/ # Module proxy protocol
/
/ A Go module proxy is any web server that can respond to GET requests for
/ URLs of a specified form. The requests have no query parameters, so even
/ a site serving from a fixed file system (including a file:/// URL)
/ can be a module proxy.
/
/ For details on the GOPROXY protocol, see
/ https://golang.org/ref/mod#goproxy-protocol.
/
/ # Import path syntax
/
/ An import path (see 'go help packages') denotes a package stored in the local
/ file system. In general, an import path denotes either a standard package (such
/ as "unicode/utf8") or a package found in one of the work spaces (For more
/ details see: 'go help gopath').
/
/ # Relative import paths
/
/ An import path beginning with ./ or ../ is called a relative path.
/ The toolchain supports relative import paths as a shortcut in two ways.
/
/ First, a relative path can be used as a shorthand on the command line.
/ If you are working in the directory containing the code imported as
/ "unicode" and want to run the tests for "unicode/utf8", you can type
/ "go test ./utf8" instead of needing to specify the full path.
/ Similarly, in the reverse situation, "go test .." will test "unicode" from
/ the "unicode/utf8" directory. Relative patterns are also allowed, like
/ "go test ./..." to test all subdirectories. See 'go help packages' for details
/ on the pattern syntax.
/
/ Second, if you are compiling a Go program not in a work space,
/ you can use a relative path in an import statement in that program
/ to refer to nearby code also not in a work space.
/ This makes it easy to experiment with small multipackage programs
/ outside of the usual work spaces, but such programs cannot be
/ installed with "go install" (there is no work space in which to install them),
/ so they are rebuilt from scratch each time they are built.
/ To avoid ambiguity, Go programs cannot use relative import paths
/ within a work space.
/
/ # Remote import paths
/
/ Certain import paths also
/ describe how to obtain the source code for the package using
/ a revision control system.
/
/ A few common code hosting sites have special syntax:
/
/ Bitbucket (Git, Mercurial)
/
/ import "bitbucket.org/user/project"
/ import "bitbucket.org/user/project/sub/directory"
/
/ GitHub (Git)
/
/ import "github.com/user/project"
/ import "github.com/user/project/sub/directory"
/
/ Launchpad (Bazaar)
/
/ import "launchpad.net/project"
/ import "launchpad.net/project/series"
/ import "launchpad.net/project/series/sub/directory"
/
/ import "launchpad.net/~user/project/branch"
/ import "launchpad.net/~user/project/branch/sub/directory"
/
/ IBM DevOps Services (Git)
/
/ import "hub.jazz.net/git/user/project"
/ import "hub.jazz.net/git/user/project/sub/directory"
/
/ For code hosted on other servers, import paths may either be qualified
/ with the version control type, or the go tool can dynamically fetch
/ the import path over https/http and discover where the code resides
/ from a <meta> tag in the HTML.
/
/ To declare the code location, an import path of the form
/
/ repository.vcs/path
/
/ specifies the given repository, with or without the .vcs suffix,
/ using the named version control system, and then the path inside
/ that repository. The supported version control systems are:
/
/ Bazaar .bzr
/ Fossil .fossil
/ Git .git
/ Mercurial .hg
/ Subversion .svn
/
/ For example,
/
/ import "example.org/user/foo.hg"
/
/ denotes the root directory of the Mercurial repository at
/ example.org/user/foo or foo.hg, and
/
/ import "example.org/repo.git/foo/bar"
/
/ denotes the foo/bar directory of the Git repository at
/ example.org/repo or repo.git.
/
/ When a version control system supports multiple protocols,
/ each is tried in turn when downloading. For example, a Git
/ download tries https://, then git+ssh://.
/
/ By default, downloads are restricted to known secure protocols
/ (e.g. https, ssh). To override this setting for Git downloads, the
/ GIT_ALLOW_PROTOCOL environment variable can be set (For more details see:
/ 'go help environment').
/
/ If the import path is not a known code hosting site and also lacks a
/ version control qualifier, the go tool attempts to fetch the import
/ over https/http and looks for a <meta> tag in the document's HTML
/ <head>.
/
/ The meta tag has the form:
/
/ <meta name="go-import" content="import-prefix vcs repo-root">
/
/ The import-prefix is the import path corresponding to the repository
/ root. It must be a prefix or an exact match of the package being
/ fetched with "go get". If it's not an exact match, another http
/ request is made at the prefix to verify the <meta> tags match.
/
/ The meta tag should appear as early in the file as possible.
/ In particular, it should appear before any raw JavaScript or CSS,
/ to avoid confusing the go command's restricted parser.
/
/ The vcs is one of "bzr", "fossil", "git", "hg", "svn".
/
/ The repo-root is the root of the version control system
/ containing a scheme and not containing a .vcs qualifier.
/
/ For example,
/
/ import "example.org/pkg/foo"
/
/ will result in the following requests:
/
/ https://example.org/pkg/foo?go-get=1 (preferred)
/ http://example.org/pkg/foo?go-get=1 (fallback, only with use of correctly set GOINSECURE)
/
/ If that page contains the meta tag
/
/ <meta name="go-import" content="example.org git https://code.org/r/p/exproj">
/
/ the go tool will verify that https://example.org/?go-get=1 contains the
/ same meta tag and then git clone https://code.org/r/p/exproj into
/ GOPATH/src/example.org.
/
/ When using GOPATH, downloaded packages are written to the first directory
/ listed in the GOPATH environment variable.
/ (See 'go help gopath-get' and 'go help gopath'.)
/
/ When using modules, downloaded packages are stored in the module cache.
/ See https://golang.org/ref/mod#module-cache.
/
/ When using modules, an additional variant of the go-import meta tag is
/ recognized and is preferred over those listing version control systems.
/ That variant uses "mod" as the vcs in the content value, as in:
/
/ <meta name="go-import" content="example.org mod https://code.org/moduleproxy">
/
/ This tag means to fetch modules with paths beginning with example.org
/ from the module proxy available at the URL https://code.org/moduleproxy.
/ See https://golang.org/ref/mod#goproxy-protocol for details about the
/ proxy protocol.
/
/ # Import path checking
/
/ When the custom import path feature described above redirects to a
/ known code hosting site, each of the resulting packages has two possible
/ import paths, using the custom domain or the known hosting site.
/
/ A package statement is said to have an "import comment" if it is immediately
/ followed (before the next newline) by a comment of one of these two forms:
/
/ package math / import "path"
/ package math /* import "path" */
/
/ The go command will refuse to install a package with an import comment
/ unless it is being referred to by that import path. In this way, import comments
/ let package authors make sure the custom import path is used and not a
/ direct path to the underlying code hosting site.
/
/ Import path checking is disabled for code found within vendor trees.
/ This makes it possible to copy code into alternate locations in vendor trees
/ without needing to update import comments.
/
/ Import path checking is also disabled when using modules.
/ Import path comments are obsoleted by the go.mod file's module statement.
/
/ See https://golang.org/s/go14customimport for details.
/
/ # Modules, module versions, and more
/
/ Modules are how Go manages dependencies.
/
/ A module is a collection of packages that are released, versioned, and
/ distributed together. Modules may be downloaded directly from version control
/ repositories or from module proxy servers.
/
/ For a series of tutorials on modules, see
/ https://golang.org/doc/tutorial/create-module.
/
/ For a detailed reference on modules, see https://golang.org/ref/mod.
/
/ By default, the go command may download modules from https://proxy.golang.org.
/ It may authenticate modules using the checksum database at
/ https://sum.golang.org. Both services are operated by the Go team at Google.
/ The privacy policies for these services are available at
/ https://proxy.golang.org/privacy and https://sum.golang.org/privacy,
/ respectively.
/
/ The go command's download behavior may be configured using GOPROXY, GOSUMDB,
/ GOPRIVATE, and other environment variables. See 'go help environment'
/ and https://golang.org/ref/mod#private-module-privacy for more information.
/
/ # Module authentication using go.sum
/
/ When the go command downloads a module zip file or go.mod file into the
/ module cache, it computes a cryptographic hash and compares it with a known
/ value to verify the file hasn't changed since it was first downloaded. Known
/ hashes are stored in a file in the module root directory named go.sum. Hashes
/ may also be downloaded from the checksum database depending on the values of
/ GOSUMDB, GOPRIVATE, and GONOSUMDB.
/
/ For details, see https://golang.org/ref/mod#authenticating.
/
/ # Package lists and patterns
/
/ Many commands apply to a set of packages:
/
/ go action [packages]
/
/ Usually, [packages] is a list of import paths.
/
/ An import path that is a rooted path or that begins with
/ a . or .. element is interpreted as a file system path and
/ denotes the package in that directory.
/
/ Otherwise, the import path P denotes the package found in
/ the directory DIR/src/P for some DIR listed in the GOPATH
/ environment variable (For more details see: 'go help gopath').
/
/ If no import paths are given, the action applies to the
/ package in the current directory.
/
/ There are four reserved names for paths that should not be used
/ for packages to be built with the go tool:
/
/ - "main" denotes the top-level package in a stand-alone executable.
/
/ - "all" expands to all packages found in all the GOPATH
/ trees. For example, 'go list all' lists all the packages on the local
/ system. When using modules, "all" expands to all packages in
/ the main module and their dependencies, including dependencies
/ needed by tests of any of those.
/
/ - "std" is like all but expands to just the packages in the standard
/ Go library.
/
/ - "cmd" expands to the Go repository's commands and their
/ internal libraries.
/
/ Import paths beginning with "cmd/" only match source code in
/ the Go repository.
/
/ An import path is a pattern if it includes one or more "..." wildcards,
/ each of which can match any string, including the empty string and
/ strings containing slashes. Such a pattern expands to all package
/ directories found in the GOPATH trees with names matching the
/ patterns.
/
/ To make common patterns more convenient, there are two special cases.
/ First, /... at the end of the pattern can match an empty string,
/ so that net/... matches both net and packages in its subdirectories, like net/http.
/ Second, any slash-separated pattern element containing a wildcard never
/ participates in a match of the "vendor" element in the path of a vendored
/ package, so that ./... does not match packages in subdirectories of
/ ./vendor or ./mycode/vendor, but ./vendor/... and ./mycode/vendor/... do.
/ Note, however, that a directory named vendor that itself contains code
/ is not a vendored package: cmd/vendor would be a command named vendor,
/ and the pattern cmd/... matches it.
/ See golang.org/s/go15vendor for more about vendoring.
/
/ An import path can also name a package to be downloaded from
/ a remote repository. Run 'go help importpath' for details.
/
/ Every package in a program must have a unique import path.
/ By convention, this is arranged by starting each path with a
/ unique prefix that belongs to you. For example, paths used
/ internally at Google all begin with 'google', and paths
/ denoting remote repositories begin with the path to the code,
/ such as 'github.com/user/repo'.
/
/ Packages in a program need not have unique package names,
/ but there are two reserved package names with special meaning.
/ The name main indicates a command, not a library.
/ Commands are built into binaries and cannot be imported.
/ The name documentation indicates documentation for
/ a non-Go program in the directory. Files in package documentation
/ are ignored by the go command.
/
/ As a special case, if the package list is a list of .go files from a
/ single directory, the command is applied to a single synthesized
/ package made up of exactly those files, ignoring any build constraints
/ in those files and ignoring any other files in the directory.
/
/ Directory and file names that begin with "." or "_" are ignored
/ by the go tool, as are directories named "testdata".
/
/ # Configuration for downloading non-public code
/
/ The go command defaults to downloading modules from the public Go module
/ mirror at proxy.golang.org. It also defaults to validating downloaded modules,
/ regardless of source, against the public Go checksum database at sum.golang.org.
/ These defaults work well for publicly available source code.
/
/ The GOPRIVATE environment variable controls which modules the go command
/ considers to be private (not available publicly) and should therefore not use
/ the proxy or checksum database. The variable is a comma-separated list of
/ glob patterns (in the syntax of Go's path.Match) of module path prefixes.
/ For example,
/
/ GOPRIVATE=*.corp.example.com,rsc.io/private
/
/ causes the go command to treat as private any module with a path prefix
/ matching either pattern, including git.corp.example.com/xyzzy, rsc.io/private,
/ and rsc.io/private/quux.
/
/ For fine-grained control over module download and validation, the GONOPROXY
/ and GONOSUMDB environment variables accept the same kind of glob list
/ and override GOPRIVATE for the specific decision of whether to use the proxy
/ and checksum database, respectively.
/
/ For example, if a company ran a module proxy serving private modules,
/ users would configure go using:
/
/ GOPRIVATE=*.corp.example.com
/ GOPROXY=proxy.example.com
/ GONOPROXY=none
/
/ The GOPRIVATE variable is also used to define the "public" and "private"
/ patterns for the GOVCS variable; see 'go help vcs'. For that usage,
/ GOPRIVATE applies even in GOPATH mode. In that case, it matches import paths
/ instead of module paths.
/
/ The 'go env -w' command (see 'go help env') can be used to set these variables
/ for future go command invocations.
/
/ For more details, see https://golang.org/ref/mod#private-modules.
/
/ # Testing flags
/
/ The 'go test' command takes both flags that apply to 'go test' itself
/ and flags that apply to the resulting test binary.
/
/ Several of the flags control profiling and write an execution profile
/ suitable for "go tool pprof"; run "go tool pprof -h" for more
/ information. The --alloc_space, --alloc_objects, and --show_bytes
/ options of pprof control how the information is presented.
/
/ The following flags are recognized by the 'go test' command and
/ control the execution of any test:
/
/ -bench regexp
/ Run only those benchmarks matching a regular expression.
/ By default, no benchmarks are run.
/ To run all benchmarks, use '-bench .' or '-bench=.'.
/ The regular expression is split by unbracketed slash (/)
/ characters into a sequence of regular expressions, and each
/ part of a benchmark's identifier must match the corresponding
/ element in the sequence, if any. Possible parents of matches
/ are run with b.N=1 to identify sub-benchmarks. For example,
/ given -bench=X/Y, top-level benchmarks matching X are run
/ with b.N=1 to find any sub-benchmarks matching Y, which are
/ then run in full.
/
/ -benchtime t
/ Run enough iterations of each benchmark to take t, specified
/ as a time.Duration (for example, -benchtime 1h30s).
/ The default is 1 second (1s).
/ The special syntax Nx means to run the benchmark N times
/ (for example, -benchtime 100x).
/
/ -count n
/ Run each test, benchmark, and fuzz seed n times (default 1).
/ If -cpu is set, run n times for each GOMAXPROCS value.
/ Examples are always run once. -count does not apply to
/ fuzz tests matched by -fuzz.
/
/ -cover
/ Enable coverage analysis.
/ Note that because coverage works by annotating the source
/ code before compilation, compilation and test failures with
/ coverage enabled may report line numbers that don't correspond
/ to the original sources.
/
/ -covermode set,count,atomic
/ Set the mode for coverage analysis for the package[s]
/ being tested. The default is "set" unless -race is enabled,
/ in which case it is "atomic".
/ The values:
/ set: bool: does this statement run?
/ count: int: how many times does this statement run?
/ atomic: int: count, but correct in multithreaded tests;
/ significantly more expensive.
/ Sets -cover.
/
/ -coverpkg pattern1,pattern2,pattern3
/ Apply coverage analysis in each test to packages matching the patterns.
/ The default is for each test to analyze only the package being tested.
/ See 'go help packages' for a description of package patterns.
/ Sets -cover.
/
/ -cpu 1,2,4
/ Specify a list of GOMAXPROCS values for which the tests, benchmarks or
/ fuzz tests should be executed. The default is the current value
/ of GOMAXPROCS. -cpu does not apply to fuzz tests matched by -fuzz.
/
/ -failfast
/ Do not start new tests after the first test failure.
/
/ -fuzz regexp
/ Run the fuzz test matching the regular expression. When specified,
/ the command line argument must match exactly one package within the
/ main module, and regexp must match exactly one fuzz test within
/ that package. Fuzzing will occur after tests, benchmarks, seed corpora
/ of other fuzz tests, and examples have completed. See the Fuzzing
/ section of the testing package documentation for details.
/
/ -fuzztime t
/ Run enough iterations of the fuzz target during fuzzing to take t,
/ specified as a time.Duration (for example, -fuzztime 1h30s).
/ The default is to run forever.
/ The special syntax Nx means to run the fuzz target N times
/ (for example, -fuzztime 1000x).
/
/ -fuzzminimizetime t
/ Run enough iterations of the fuzz target during each minimization
/ attempt to take t, as specified as a time.Duration (for example,
/ -fuzzminimizetime 30s).
/ The default is 60s.
/ The special syntax Nx means to run the fuzz target N times
/ (for example, -fuzzminimizetime 100x).
/
/ -json
/ Log verbose output and test results in JSON. This presents the
/ same information as the -v flag in a machine-readable format.
/
/ -list regexp
/ List tests, benchmarks, fuzz tests, or examples matching the regular
/ expression. No tests, benchmarks, fuzz tests, or examples will be run.
/ This will only list top-level tests. No subtest or subbenchmarks will be
/ shown.
/
/ -parallel n
/ Allow parallel execution of test functions that call t.Parallel, and
/ fuzz targets that call t.Parallel when running the seed corpus.
/ The value of this flag is the maximum number of tests to run
/ simultaneously.
/ While fuzzing, the value of this flag is the maximum number of
/ subprocesses that may call the fuzz function simultaneously, regardless of
/ whether T.Parallel is called.
/ By default, -parallel is set to the value of GOMAXPROCS.
/ Setting -parallel to values higher than GOMAXPROCS may cause degraded
/ performance due to CPU contention, especially when fuzzing.
/ Note that -parallel only applies within a single test binary.
/ The 'go test' command may run tests for different packages
/ in parallel as well, according to the setting of the -p flag
/ (see 'go help build').
/
/ -run regexp
/ Run only those tests, examples, and fuzz tests matching the regular
/ expression. For tests, the regular expression is split by unbracketed
/ slash (/) characters into a sequence of regular expressions, and each
/ part of a test's identifier must match the corresponding element in
/ the sequence, if any. Note that possible parents of matches are
/ run too, so that -run=X/Y matches and runs and reports the result
/ of all tests matching X, even those without sub-tests matching Y,
/ because it must run them to look for those sub-tests.
/
/ -short
/ Tell long-running tests to shorten their run time.
/ It is off by default but set during all.bash so that installing
/ the Go tree can run a sanity check but not spend time running
/ exhaustive tests.
/
/ -shuffle off,on,N
/ Randomize the execution order of tests and benchmarks.
/ It is off by default. If -shuffle is set to on, then it will seed
/ the randomizer using the system clock. If -shuffle is set to an
/ integer N, then N will be used as the seed value. In both cases,
/ the seed will be reported for reproducibility.
/
/ -timeout d
/ If a test binary runs longer than duration d, panic.
/ If d is 0, the timeout is disabled.
/ The default is 10 minutes (10m).
/
/ -v
/ Verbose output: log all tests as they are run. Also print all
/ text from Log and Logf calls even if the test succeeds.
/
/ -vet list
/ Configure the invocation of "go vet" during "go test"
/ to use the comma-separated list of vet checks.
/ If list is empty, "go test" runs "go vet" with a curated list of
/ checks believed to be always worth addressing.
/ If list is "off", "go test" does not run "go vet" at all.
/
/ The following flags are also recognized by 'go test' and can be used to
/ profile the tests during execution:
/
/ -benchmem
/ Print memory allocation statistics for benchmarks.
/
/ -blockprofile block.out
/ Write a goroutine blocking profile to the specified file
/ when all tests are complete.
/ Writes test binary as -c would.
/
/ -blockprofilerate n
/ Control the detail provided in goroutine blocking profiles by
/ calling runtime.SetBlockProfileRate with n.
/ See 'go doc runtime.SetBlockProfileRate'.
/ The profiler aims to sample, on average, one blocking event every
/ n nanoseconds the program spends blocked. By default,
/ if -test.blockprofile is set without this flag, all blocking events
/ are recorded, equivalent to -test.blockprofilerate=1.
/
/ -coverprofile cover.out
/ Write a coverage profile to the file after all tests have passed.
/ Sets -cover.
/
/ -cpuprofile cpu.out
/ Write a CPU profile to the specified file before exiting.
/ Writes test binary as -c would.
/
/ -memprofile mem.out
/ Write an allocation profile to the file after all tests have passed.
/ Writes test binary as -c would.
/
/ -memprofilerate n
/ Enable more precise (and expensive) memory allocation profiles by
/ setting runtime.MemProfileRate. See 'go doc runtime.MemProfileRate'.
/ To profile all memory allocations, use -test.memprofilerate=1.
/
/ -mutexprofile mutex.out
/ Write a mutex contention profile to the specified file
/ when all tests are complete.
/ Writes test binary as -c would.
/
/ -mutexprofilefraction n
/ Sample 1 in n stack traces of goroutines holding a
/ contended mutex.
/
/ -outputdir directory
/ Place output files from profiling in the specified directory,
/ by default the directory in which "go test" is running.
/
/ -trace trace.out
/ Write an execution trace to the specified file before exiting.
/
/ Each of these flags is also recognized with an optional 'test.' prefix,
/ as in -test.v. When invoking the generated test binary (the result of
/ 'go test -c') directly, however, the prefix is mandatory.
/
/ The 'go test' command rewrites or removes recognized flags,
/ as appropriate, both before and after the optional package list,
/ before invoking the test binary.
/
/ For instance, the command
/
/ go test -v -myflag testdata -cpuprofile=prof.out -x
/
/ will compile the test binary and then run it as
/
/ pkg.test -test.v -myflag testdata -test.cpuprofile=prof.out
/
/ (The -x flag is removed because it applies only to the go command's
/ execution, not to the test itself.)
/
/ The test flags that generate profiles (other than for coverage) also
/ leave the test binary in pkg.test for use when analyzing the profiles.
/
/ When 'go test' runs a test binary, it does so from within the
/ corresponding package's source code directory. Depending on the test,
/ it may be necessary to do the same when invoking a generated test
/ binary directly. Because that directory may be located within the
/ module cache, which may be read-only and is verified by checksums, the
/ test must not write to it or any other directory within the module
/ unless explicitly requested by the user (such as with the -fuzz flag,
/ which writes failures to testdata/fuzz).
/
/ The command-line package list, if present, must appear before any
/ flag not known to the go test command. Continuing the example above,
/ the package list would have to appear before -myflag, but could appear
/ on either side of -v.
/
/ When 'go test' runs in package list mode, 'go test' caches successful
/ package test results to avoid unnecessary repeated running of tests. To
/ disable test caching, use any test flag or argument other than the
/ cacheable flags. The idiomatic way to disable test caching explicitly
/ is to use -count=1.
/
/ To keep an argument for a test binary from being interpreted as a
/ known flag or a package name, use -args (see 'go help test') which
/ passes the remainder of the command line through to the test binary
/ uninterpreted and unaltered.
/
/ For instance, the command
/
/ go test -v -args -x -v
/
/ will compile the test binary and then run it as
/
/ pkg.test -test.v -x -v
/
/ Similarly,
/
/ go test -args math
/
/ will compile the test binary and then run it as
/
/ pkg.test math
/
/ In the first example, the -x and the second -v are passed through to the
/ test binary unchanged and with no effect on the go command itself.
/ In the second example, the argument math is passed through to the test
/ binary, instead of being interpreted as the package list.
/
/ # Testing functions
/
/ The 'go test' command expects to find test, benchmark, and example functions
/ in the "*_test.go" files corresponding to the package under test.
/
/ A test function is one named TestXxx (where Xxx does not start with a
/ lower case letter) and should have the signature,
/
/ func TestXxx(t *testing.T) { ... }
/
/ A benchmark function is one named BenchmarkXxx and should have the signature,
/
/ func BenchmarkXxx(b *testing.B) { ... }
/
/ A fuzz test is one named FuzzXxx and should have the signature,
/
/ func FuzzXxx(f *testing.F) { ... }
/
/ An example function is similar to a test function but, instead of using
/ *testing.T to report success or failure, prints output to os.Stdout.
/ If the last comment in the function starts with "Output:" then the output
/ is compared exactly against the comment (see examples below). If the last
/ comment begins with "Unordered output:" then the output is compared to the
/ comment, however the order of the lines is ignored. An example with no such
/ comment is compiled but not executed. An example with no text after
/ "Output:" is compiled, executed, and expected to produce no output.
/
/ Godoc displays the body of ExampleXxx to demonstrate the use
/ of the function, constant, or variable Xxx. An example of a method M with
/ receiver type T or *T is named ExampleT_M. There may be multiple examples
/ for a given function, constant, or variable, distinguished by a trailing _xxx,
/ where xxx is a suffix not beginning with an upper case letter.
/
/ Here is an example of an example:
/
/ func ExamplePrintln() {
/ Println("The output of\nthis example.")
/ / Output: The output of
/ / this example.
/ }
/
/ Here is another example where the ordering of the output is ignored:
/
/ func ExamplePerm() {
/ for _, value := range Perm(4) {
/ fmt.Println(value)
/ }
/
/ / Unordered output: 4
/ / 2
/ / 1
/ / 3
/ / 0
/ }
/
/ The entire test file is presented as the example when it contains a single
/ example function, at least one other function, type, variable, or constant
/ declaration, and no tests, benchmarks, or fuzz tests.
/
/ See the documentation of the testing package for more information.
/
/ # Controlling version control with GOVCS
/
/ The 'go get' command can run version control commands like git
/ to download imported code. This functionality is critical to the decentralized
/ Go package ecosystem, in which code can be imported from any server,
/ but it is also a potential security problem, if a malicious server finds a
/ way to cause the invoked version control command to run unintended code.
/
/ To balance the functionality and security concerns, the 'go get' command
/ by default will only use git and hg to download code from public servers.
/ But it will use any known version control system (bzr, fossil, git, hg, svn)
/ to download code from private servers, defined as those hosting packages
/ matching the GOPRIVATE variable (see 'go help private'). The rationale behind
/ allowing only Git and Mercurial is that these two systems have had the most
/ attention to issues of being run as clients of untrusted servers. In contrast,
/ Bazaar, Fossil, and Subversion have primarily been used in trusted,
/ authenticated environments and are not as well scrutinized as attack surfaces.
/
/ The version control command restrictions only apply when using direct version
/ control access to download code. When downloading modules from a proxy,
/ 'go get' uses the proxy protocol instead, which is always permitted.
/ By default, the 'go get' command uses the Go module mirror (proxy.golang.org)
/ for public packages and only falls back to version control for private
/ packages or when the mirror refuses to serve a public package (typically for
/ legal reasons). Therefore, clients can still access public code served from
/ Bazaar, Fossil, or Subversion repositories by default, because those downloads
/ use the Go module mirror, which takes on the security risk of running the
/ version control commands using a custom sandbox.
/
/ The GOVCS variable can be used to change the allowed version control systems
/ for specific packages (identified by a module or import path).
/ The GOVCS variable applies when building package in both module-aware mode
/ and GOPATH mode. When using modules, the patterns match against the module path.
/ When using GOPATH, the patterns match against the import path corresponding to
/ the root of the version control repository.
/
/ The general form of the GOVCS setting is a comma-separated list of
/ pattern:vcslist rules. The pattern is a glob pattern that must match
/ one or more leading elements of the module or import path. The vcslist
/ is a pipe-separated list of allowed version control commands, or "all"
/ to allow use of any known command, or "off" to disallow all commands.
/ Note that if a module matches a pattern with vcslist "off", it may still be
/ downloaded if the origin server uses the "mod" scheme, which instructs the
/ go command to download the module using the GOPROXY protocol.
/ The earliest matching pattern in the list applies, even if later patterns
/ might also match.
/
/ For example, consider:
/
/ GOVCS=github.com:git,evil.com:off,*:git|hg
/
/ With this setting, code with a module or import path beginning with
/ github.com/ can only use git; paths on evil.com cannot use any version
/ control command, and all other paths (* matches everything) can use
/ only git or hg.
/
/ The special patterns "public" and "private" match public and private
/ module or import paths. A path is private if it matches the GOPRIVATE
/ variable; otherwise it is public.
/
/ If no rules in the GOVCS variable match a particular module or import path,
/ the 'go get' command applies its default rule, which can now be summarized
/ in GOVCS notation as 'public:git|hg,private:all'.
/
/ To allow unfettered use of any version control system for any package, use:
/
/ GOVCS=*:all
/
/ To disable all use of version control, use:
/
/ GOVCS=*:off
/
/ The 'go env -w' command (see 'go help env') can be used to set the GOVCS
/ variable for future go command invocations.
package main