Xargs Command
From Luke Jackson
xargs -- build and execute command lines from standard input
Contents |
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 -lrt | cut -c 35- | grep ^May | cut -c 14- | xargs -iX -t mv X 2007/05-May/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