Linux Pocket Guide, 2nd Edition

Name

xargs — stdin  stdout  - file  -- opt  --help  --version

Synopsis

xargs [options] [command]

xargs is one of the oddest yet most powerful commands available to the shell. It reads lines of text from standard input, turns them into commands, and executes them. This might not sound exciting, but xargs has some unique uses, particularly for processing a list of files you’ve located. Suppose you made a file named important that lists important files, one per line:

$ cat important
/home/jsmith/mail/love-letters
/usr/local/lib/critical_stuff
/etc/passwd
...

With xargs, you can process each of these files easily with other Linux commands. For instance, the following command runs the ls -l command on all the listed files:

$ cat important | xargs ls -l

Similarly, you can view the files with less:

$ cat important | xargs less

and even delete them with rm:

$ cat important | xargs rm -f

Each of these pipelines reads the list of files from important and produces and runs new Linux commands based on the list. The power begins when the input list doesn’t come from a file, but from another command writing to standard output. In particular, the find command, which prints a list of files on standard output, makes a great partner for xargs. For example, to search your current directory hierarchy for files containing the word “myxomatosis”:

$ find . -print | xargs grep -l myxomatosis

This power comes with one warning: if any of the files located by find contains whitespace in its name, this will confuse grep ...