golang exec 代码
文件路径：/src/cmd/dist/exec.go
/ Copyright 2021 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.
package main
import (
"os"
"os/exec"
"strings"
)
/ setDir sets cmd.Dir to dir, and also adds PWD=dir to cmd's environment.
func setDir(cmd *exec.Cmd, dir string) {
cmd.Dir = dir
setEnv(cmd, "PWD", dir)
}
/ setEnv sets cmd.Env so that key = value.
/
/ It first removes any existing values for key, so it is safe to call
/ even from within cmdbootstrap.
func setEnv(cmd *exec.Cmd, key, value string) {
kv := key + "=" + value
if cmd.Env == nil {
cmd.Env = os.Environ()
}
prefix := kv[:len(key)+1]
for i, entry := range cmd.Env {
if strings.HasPrefix(entry, prefix) {
cmd.Env[i] = kv
return
}
}
cmd.Env = append(cmd.Env, kv)
}
/ unsetEnv sets cmd.Env so that key is not present in the environment.
func unsetEnv(cmd *exec.Cmd, key string) {
if cmd.Env == nil {
cmd.Env = os.Environ()
}
prefix := key + "="
for i, entry := range cmd.Env {
if strings.HasPrefix(entry, prefix) {
cmd.Env = append(cmd.Env[:i], cmd.Env[i+1:]...)
return
}
}
}