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Source file src/os/exec/lp_plan9.go

Documentation: os/exec

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package exec
     6  
     7  import (
     8  	"errors"
     9  	"os"
    10  	"path/filepath"
    11  	"strings"
    12  )
    13  
    14  // ErrNotFound is the error resulting if a path search failed to find an executable file.
    15  var ErrNotFound = errors.New("executable file not found in $path")
    16  
    17  func findExecutable(file string) error {
    18  	d, err := os.Stat(file)
    19  	if err != nil {
    20  		return err
    21  	}
    22  	if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
    23  		return nil
    24  	}
    25  	return os.ErrPermission
    26  }
    27  
    28  // LookPath searches for an executable binary named file
    29  // in the directories named by the path environment variable.
    30  // If file begins with "/", "#", "./", or "../", it is tried
    31  // directly and the path is not consulted.
    32  // The result may be an absolute path or a path relative to the current directory.
    33  func LookPath(file string) (string, error) {
    34  	// skip the path lookup for these prefixes
    35  	skip := []string{"/", "#", "./", "../"}
    36  
    37  	for _, p := range skip {
    38  		if strings.HasPrefix(file, p) {
    39  			err := findExecutable(file)
    40  			if err == nil {
    41  				return file, nil
    42  			}
    43  			return "", &Error{file, err}
    44  		}
    45  	}
    46  
    47  	path := os.Getenv("path")
    48  	for _, dir := range filepath.SplitList(path) {
    49  		path := filepath.Join(dir, file)
    50  		if err := findExecutable(path); err == nil {
    51  			return path, nil
    52  		}
    53  	}
    54  	return "", &Error{file, ErrNotFound}
    55  }
    56  

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