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// Copyright 2010 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.
// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
package exec
import (
"errors"
"os"
"strings"
)
// ErrNotFound is the error resulting if a path search failed to find an executable file.
var ErrNotFound = errors.New("executable file not found in $PATH")
func findExecutable(file string) error {
d, err := os.Stat(file)
if err != nil {
return err
}
if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
return nil
}
return os.ErrPermission
}
// LookPath searches for an executable binary named file
// in the directories named by the PATH environment variable.
// If file contains a slash, it is tried directly and the PATH is not consulted.
// The result may be an absolute path or a path relative to the current directory.
func LookPath(file string) (string, error) {
// NOTE(rsc): I wish we could use the Plan 9 behavior here
// (only bypass the path if file begins with / or ./ or ../)
// but that would not match all the Unix shells.
if strings.Contains(file, "/") {
err := findExecutable(file)
if err == nil {
return file, nil
}
return "", &Error{file, err}
}
pathenv := os.Getenv("PATH")
if pathenv == "" {
return "", &Error{file, ErrNotFound}
}
for _, dir := range strings.Split(pathenv, ":") {
if dir == "" {
// Unix shell semantics: path element "" means "."
dir = "."
}
path := dir + "/" + file
if err := findExecutable(path); err == nil {
return path, nil
}
}
return "", &Error{file, ErrNotFound}
}
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