Xargs Command

From Luke Jackson

xargs -- build and execute command lines from standard input

Contents 1 Introduction 2 Syntax 3 Usage 4 Examples 4.1 Moving Files

Introduction

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.

Syntax

-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.

Usage

xargs [options] [command]

Examples

Moving Files

Using cut, in combination with grep, cat, find, ls, and "etc" to move files:

ls -l | grep Dec | cut -c 44-64 | xargs -iX -t mv $PWD/X 12-December/X

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