替代xargs的-l [英] Alternatives to xargs -l

问题描述

我要重新命名了一堆从DIR迪尔斯到DIR.OLD的。理想情况下，我会用以下内容：

I want to rename a bunch of dirs from DIR to DIR.OLD. Ideally I would use the following:

find . -maxdepth 1 -type d -name \"*.y\" -mtime +`expr 2 \* 365` -print0 | xargs -0 -r -I file mv file file.old

不过该机我想在有执行此安装的BusyBox和BusyBox的xargs的不支持-I选项。

But the machine I want to execute this on has BusyBox installed and the BusyBox xargs doesn't support the "-I" option.

什么是收集文件的数组，然后在shell脚本对他们执行？一些常见的替代方法。

What are some common alternative methods for collecting an array of files and then executing on them in a shell script?

推荐答案

您可以使用 -exec 和 {} 特征的找到命令，所以你不需要任何管道都：

You can use -exec and {} features of the find command so you don't need any pipes at all:

find -maxdepth 1 -type d -name "*.y" -mtime +`expr 2 \* 365` -exec mv "{}" "{}.old" \;

你也不必指定'。路径 - 这是默认找到。而且你用多余的斜线在* Y。当然，如果你的文件名真的不包含引号。

Also you don't need to specify '.' path - this is default for find. And you used extra slashes in "*.y". Of course if your file names do not really contain quotes.

在公平，应该注意的是，版本而读循环是最快的这里提出。下面是一些例子测量：

In fairness it should be noted, that version with while read loop is the fastest of proposed here. Here are some example measurements:

$ cat measure 
#!/bin/sh
case $2 in
  1) find "$1" -print0 | xargs -0 -I file echo mv file file.old ;;

  2) find "$1" -exec echo mv '{}' '{}.old' \; ;;

  3) find "$1" | while read file; do
       echo mv "$file" "$file.old"
     done;;
esac
$ time ./measure android-ndk-r5c 1 | wc
   6225   18675  955493
real    0m6.585s
user    0m18.933s
sys     0m4.476s
$ time ./measure android-ndk-r5c 2 | wc
   6225   18675  955493
real    0m6.877s
user    0m18.517s
sys     0m4.788s
$ time ./measure android-ndk-r5c 3 | wc
   6225   18675  955493
real    0m0.262s
user    0m0.088s
sys     0m0.236s

我想这是因为找到和的xargs 调用额外的/ bin / sh的（实际上执行exec（3）做的话）执行命令每一次，而壳，而循环没有。

I think it's because find and xargs invokes additional /bin/sh (actually exec(3) does it) every time for execute a command, while shell while loop do not.

UPD：如果你的busybox版本没有 -exec 编为找到命令则，而环或的xargs ，建议在其他的答案（的one ， 2 ），是你的方式。

Upd: If your busybox version was compiled without -exec option support for the find command then the while loop or xargs, suggested in the other answers (one, two), is your way.

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