xargs是給命令傳遞參數(shù)的一個過濾器，也是組合多個命令的一個工具。它把一個數(shù)據(jù)流分割為一些足夠小的塊，以方便過濾器和命令進(jìn)行處理。通常情況下，xargs從管道或者stdin中讀取數(shù)據(jù)，但是它也能夠從文件的輸出中讀取數(shù)據(jù)。xargs的默認(rèn)命令是echo，這意味著通過管道傳遞給xargs的輸入將會包含換行和空白，不過通過xargs的處理，換行和空白將被空格取代。
xargs 是一個強(qiáng)有力的命令，它能夠捕獲一個命令的輸出，然后傳遞給另外一個命令，下面是一些如何有效使用xargs 的實(shí)用例子。
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當(dāng)你嘗試用rm 刪除太多的文件，你可能得到一個錯誤信息：/bin/rm Argument list too long. 用xargs 去避免這個問題
find ~ -name ‘*.log’ -print0 | xargs -0 rm -f -
獲得/etc/ 下所有*.conf 結(jié)尾的文件列表，有幾種不同的方法能得到相同的結(jié)果，下面的例子僅僅是示范怎么實(shí)用xargs ，在這個例子中實(shí)用 xargs將find 命令的輸出傳遞給ls -l
# find /etc -name "*.conf" | xargs ls –l -
假如你有一個文件包含了很多你希望下載的URL, 你能夠使用xargs 下載所有鏈接
# cat url-list.txt | xargs wget –c -
查找所有的jpg 文件，并且壓縮它
# find / -name *.jpg -type f -print | xargs tar -cvzf images.tar.gz -
拷貝所有的圖片文件到一個外部的硬盤驅(qū)動
# ls *.jpg | xargs -n1 -i cp {} /external-hard-drive/directory
EXAMPLES
find /tmp -name core -type f -print | xargs /bin/rm -f
Find files named core in or below the directory /tmp and delete them. Note that this will work incorrectly if there are any filenames containing newlines or spaces.
find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f
Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing spaces or newlines are correctly handled.
find /tmp -depth -name core -type f -delete
Find files named core in or below the directory /tmp and delete them, but more efficiently than in the previous example (because we avoid the need to use fork(2) and exec(2) to launch rm and we don't need the extra xargs process).
cut -d: -f1 < /etc/passwd | sort | xargs echo
Generates a compact listing of all the users on the system.
xargs sh -c 'emacs "$@" < /dev/tty' emacs
Launches the minimum number of copies of Emacs needed, one after the other, to edit the files listed on xargs' standard input. This example achieves the same effect as BSD's -o option, but in a more flexible and portable way.
