mv.go

// Copyright 2012-2018 the u-root Authors. All rights reserved
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Mv renames files and directories.
//
// Synopsis:
//     mv SOURCE [-u] TARGET
//     mv SOURCE... [-u] DIRECTORY
//
// Author:
//     Beletti (rhiguita@gmail.com)
package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"path/filepath"
)

var (
	update    = flag.Bool("u", false, "move only when the SOURCE file is newer than the destination file or when the destination file is missing")
	noClobber = flag.Bool("n", false, "do not overwrite an existing file")
)

func usage() {
	fmt.Fprintf(os.Stderr, "Usage: %s [ARGS] source target\n", os.Args[0])
	fmt.Fprintf(os.Stderr, "       %s [ARGS] source ... directory\n", os.Args[0])
	flag.PrintDefaults()
	os.Exit(1)
}

func moveFile(source string, dest string) error {

	if *noClobber {
		_, err := os.Lstat(dest)
		if !os.IsNotExist(err) {
			// This is either a real error if something unexpected happen during Lstat or nil
			return err
		}
	}

	if *update {
		sourceInfo, err := os.Lstat(source)
		if err != nil {
			return err
		}

		destInfo, err := os.Lstat(dest)
		if err != nil {
			return err
		}

		// Check if the destination already exists and was touched later than the source
		if destInfo.ModTime().After(sourceInfo.ModTime()) {
			// Source is older and we don't want to "downgrade"
			return nil
		}
	}

	if err := os.Rename(source, dest); err != nil {
		return err
	}
	return nil
}

func mv(files []string, todir bool) error {
	if len(files) == 2 && todir == false {
		// Rename/move a single file
		if err := moveFile(files[0], files[1]); err != nil {
			return err
		}
	} else {
		// Move one or more files into a directory
		destdir := files[len(files)-1]
		for _, f := range files[:len(files)-1] {
			newPath := filepath.Join(destdir, filepath.Base(f))
			if err := moveFile(f, newPath); err != nil {
				return err
			}
		}
	}
	return nil
}

func main() {
	var todir bool
	flag.Parse()

	if flag.NArg() < 2 {
		usage()
	}

	files := flag.Args()
	dest := files[len(files)-1]
	if destdir, err := os.Lstat(dest); err == nil {
		todir = destdir.IsDir()
	}
	if flag.NArg() > 2 && todir == false {
		fmt.Printf("Not a directory: %s\n", dest)
		os.Exit(1)
	}

	if err := mv(files, todir); err != nil {
		log.Fatalf("%v", err)
	}
}