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Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

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xargs

xargs [options] [command]

Execute command (with any initial arguments), but read remaining arguments from standard input instead of specifying them directly. xargs passes these arguments in several bundles to command, allowing command to process more arguments than it could normally handle at once. The arguments are typically a long list of filenames (generated by ls or find, for example) that get passed to xargs via a pipe.

Options

-0, --null

Expect filenames to be terminated by NULL instead of whitespace. Do not treat quotes or backslashes specially.

-e[string] , -E [string] , --eof[=string]

Set EOF to _ or, if specified, to string.

--help

Print a summary of the options to xargs and then exit.

-i[string] , -I [string] , --replace[=string]

Replace all occurrences of { }, or string, with the names read from standard input. Unquoted blanks are not considered argument terminators. Implies -x and -L 1.

-l[lines] , -L [lines] , --max-lines[=lines]

Allow no more than lines nonblank input lines on the command line (default is 1). Implies -x.

-n args, --max-args=args

Allow no more than args arguments on the command line. Overridden by the maximum number of characters set with -s.

-p, --interactive

Prompt for confirmation before running each command line. Implies -t.

-P max, --max-procs=max

Allow no more than max processes to run at once. The default is 1. A maximum of 0 allows as many as possible to run at once.

-r, --no-run-if-empty

Do not run command if standard input contains only blanks.

-s max, --max-chars=max

Allow no more than max characters per command line.

-t, --verbose

Verbose mode. Print command line on standard error before executing.

-x, --exit

If the maximum size (as specified by -s) is exceeded, exit.

--version

Print the version number of xargs and then exit.

Examples

grep for pattern in all files on the system:

find / | xargs grep pattern > out &

Run diff on file pairs (e.g., f1.a and f1.b, f2.a and f2.b, etc.):

echo $* | xargs -n2 diff

The previous line would be invoked as a shell script, specifying filenames as arguments. Display file, one word per line (same as deroff -w):

cat file | xargs -n1

Move files in olddir to newdir, showing each command:

ls olddir | xargs -i -t mv olddir/{ } newdir/{ }