find . -type f -name "*.jpg" -print | xargs tar -czvf images.tar.gz
xargs 其他应用
假如你有一个文件包含了很多你希望下载的 URL，你能够使用 xargs下载所有链接：
1
# cat url-list.txt | xargs wget -c
DESCRIPTION This manual page documents the GNU version of xargs. xargs reads items from the standard input, delimited by blanks (which can be pro‐ tected with double or single quotes or a backslash) or newlines, and executes the command (default is /bin/echo) one or more times with any initial-arguments followed by items read from standard input. Blank lines on the standard input are ignored.
The command line for command is built up until it reaches a system-defined limit (unless the -n and -L options are used). The speci‐
fied command will be invoked as many times as necessary to use up the list of input items. In general, there will be many fewer invo‐
cations of command than there were items in the input. This will normally have significant performance benefits. Some commands can
usefully be executed in parallel too; see the -P option.
Because Unix filenames can contain blanks and newlines, this default behaviour is often problematic; filenames containing blanks and/or
newlines are incorrectly processed by xargs. In these situations it is better to use the -0 option, which prevents such problems.
When using this option you will need to ensure that the program which produces the input for xargs also uses a null character as a sep‐
arator. If that program is GNU find for example, the -print0 option does this for you.
If any invocation of the command exits with a status of 255, xargs will stop immediately without reading any further input. An error
message is issued on stderr when this happens.
OPTIONS -0, –null Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literally). Disables the end of file string, which is treated like any other argument. Useful when input items might contain white space, quote marks, or backslashes. The GNU find -print0 option produces input suitable for this mode.
-a file, --arg-file=file
Read items from file instead of standard input. If you use this option, stdin remains unchanged when commands are run. Other‐
wise, stdin is redirected from /dev/null.
-E eof-str
Set the end of file string to eof-str. If the end of file string occurs as a line of input, the rest of the input is ignored.
If neither -E nor -e is used, no end of file string is used.
-e[eof-str], --eof[=eof-str]
This option is a synonym for the -E option. Use -E instead, because it is POSIX compliant while this option is not. If eof-str
is omitted, there is no end of file string. If neither -E nor -e is used, no end of file string is used.
-I replace-str
Replace occurrences of replace-str in the initial-arguments with names read from standard input. Also, unquoted blanks do not
terminate input items; instead the separator is the newline character. Implies -x and -L 1.
-i[replace-str], --replace[=replace-str]
This option is a synonym for -Ireplace-str if replace-str is specified. If the replace-str argument is missing, the effect is
the same as -I{}. This option is deprecated; use -I instead.
-L max-lines
Use at most max-lines nonblank input lines per command line. Trailing blanks cause an input line to be logically continued on
the next input line. Implies -x.
-l[max-lines], --max-lines[=max-lines]
Synonym for the -L option. Unlike -L, the max-lines argument is optional. If max-lines is not specified, it defaults to one.
The -l option is deprecated since the POSIX standard specifies -L instead.
-P max-procs, --max-procs=max-procs
Run up to max-procs processes at a time; the default is 1. If max-procs is 0, xargs will run as many processes as possible at a
time. Use the -n option or the -L option with -P; otherwise chances are that only one exec will be done. While xargs is run‐
ning, you can send its process a SIGUSR1 signal to increase the number of commands to run simultaneously, or a SIGUSR2 to de‐
crease the number. You cannot increase it above an implementation-defined limit (which is shown with --show-limits). You can‐
not decrease it below 1. xargs never terminates its commands; when asked to decrease, it merely waits for more than one exist‐
ing command to terminate before starting another.
Please note that it is up to the called processes to properly manage parallel access to shared resources. For example, if more
than one of them tries to print to stdout, the output will be produced in an indeterminate order (and very likely mixed up) un‐
less the processes collaborate in some way to prevent this. Using some kind of locking scheme is one way to prevent such prob‐
lems. In general, using a locking scheme will help ensure correct output but reduce performance. If you don't want to tolerate
the performance difference, simply arrange for each process to produce a separate output file (or otherwise use separate re‐
sources).
-o, --open-tty
Reopen stdin as /dev/tty in the child process before executing the command. This is useful if you want xargs to run an interac‐
tive application.
-p, --interactive
Prompt the user about whether to run each command line and read a line from the terminal. Only run the command line if the re‐
sponse starts with `y' or `Y'. Implies -t.
--process-slot-var=name
Set the environment variable name to a unique value in each running child process. Values are reused once child processes exit.
This can be used in a rudimentary load distribution scheme, for example.
-r, --no-run-if-empty
If the standard input does not contain any nonblanks, do not run the command. Normally, the command is run once even if there
is no input. This option is a GNU extension.
-s max-chars, --max-chars=max-chars
Use at most max-chars characters per command line, including the command and initial-arguments and the terminating nulls at the
ends of the argument strings. The largest allowed value is system-dependent, and is calculated as the argument length limit for
exec, less the size of your environment, less 2048 bytes of headroom. If this value is more than 128KiB, 128Kib is used as the
default value; otherwise, the default value is the maximum. 1KiB is 1024 bytes. xargs automatically adapts to tighter con‐
straints.
--show-limits
Display the limits on the command-line length which are imposed by the operating system, xargs' choice of buffer size and the -s
option. Pipe the input from /dev/null (and perhaps specify --no-run-if-empty) if you don't want xargs to do anything.
-t, --verbose
Print the command line on the standard error output before executing it.
-x, --exit
Exit if the size (see the -s option) is exceeded.
--help Print a summary of the options to xargs and exit.
--version
Print the version number of xargs and exit.
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.
EXIT STATUS xargs exits with the following status: 0 if it succeeds 123 if any invocation of the command exited with status 1-125 124 if the command exited with status 255 125 if the command is killed by a signal 126 if the command cannot be run 127 if the command is not found 1 if some other error occurred.
Exit codes greater than 128 are used by the shell to indicate that a program died due to a fatal signal.
STANDARDS CONFORMANCE As of GNU xargs version 4.2.9, the default behaviour of xargs is not to have a logical end-of-file marker. POSIX (IEEE Std 1003.1, 2004 Edition) allows this.
The -l and -i options appear in the 1997 version of the POSIX standard, but do not appear in the 2004 version of the standard. There‐
fore you should use -L and -I instead, respectively.
The -o option is an extension to the POSIX standard for better compatibility with BSD.
The POSIX standard allows implementations to have a limit on the size of arguments to the exec functions. This limit could be as low
as 4096 bytes including the size of the environment. For scripts to be portable, they must not rely on a larger value. However, I
know of no implementation whose actual limit is that small. The --show-limits option can be used to discover the actual limits in
force on the current system.
SEE ALSO find(1), locate(1), locatedb(5), updatedb(1), fork(2), execvp(3), kill(1), signal(7),
The full documentation for xargs is maintained as a Texinfo manual. If the info and xargs programs are properly installed at your
site, the command info xargs should give you access to the complete manual.
BUGS The -L option is incompatible with the -I option, but perhaps should not be.
It is not possible for xargs to be used securely, since there will always be a time gap between the production of the list of input
files and their use in the commands that xargs issues. If other users have access to the system, they can manipulate the filesystem
during this time window to force the action of the commands xargs runs to apply to files that you didn't intend. For a more detailed
discussion of this and related problems, please refer to the ``Security Considerations'' chapter in the findutils Texinfo documenta‐
tion. The -execdir option of find can often be used as a more secure alternative.
When you use the -I option, each line read from the input is buffered internally. This means that there is an upper limit on the
length of input line that xargs will accept when used with the -I option. To work around this limitation, you can use the -s option to
increase the amount of buffer space that xargs uses, and you can also use an extra invocation of xargs to ensure that very long lines
do not occur. For example:
somecommand | xargs -s 50000 echo | xargs -I '{}' -s 100000 rm '{}'
Here, the first invocation of xargs has no input line length limit because it doesn't use the -i option. The second invocation of
xargs does have such a limit, but we have ensured that the it never encounters a line which is longer than it can handle. This is not
an ideal solution. Instead, the -i option should not impose a line length limit, which is why this discussion appears in the BUGS sec‐
tion. The problem doesn't occur with the output of find(1) because it emits just one filename per line.
The best way to report a bug is to use the form at https://savannah.gnu.org/bugs/?group=findutils. The reason for this is that you
will then be able to track progress in fixing the problem. Other comments about xargs(1) and about the findutils package in general
can be sent to the bug-findutils mailing list. To join the list, send email to bug-findutils-request@gnu.org.
XARGS(1)
bno_plot (1) – generate interactive 3D plot of IO blocks and sizes gnuplot (1) – an interactive plotting program pbmtoplot (1) – convert a PBM image into a Unix 'plot' file
或许每个人的输出不同，这个主要取决于安装的软件包和索引的数据库。以上。
再来一个实例，这个应该大部分的都类似：
1 2 3 4 5 6 7 8 9 10 11 12
$ apropos who
at.allow (5) - determine who can submit jobs via at or batch at.deny (5) - determine who can submit jobs via at or batch btrfs-filesystem (8) - command group of btrfs that usually work on the whole filesystem docker-trust-signer (1) - Manage entities who can sign Docker images ipsec_newhostkey (8) - generate a new raw RSA authentication key for a host ipsec_showhostkey (8) - show host's authentication key w (1) - Show who is logged on and what they are doing. who (1) - show who is logged on who (1p) - display who is on the system whoami (1) - print effective userid
bno_plot (1) – generate interactive 3D plot of IO blocks and sizes gnuplot (1) – an interactive plotting program pbmtoplot (1) – convert a PBM image into a Unix 'plot' file
或许每个人的输出不同，这个主要取决于安装的软件包和索引的数据库。以上。
再来一个实例，这个应该大部分的都类似：
1 2 3 4 5 6 7 8 9 10 11 12
$ apropos who
at.allow (5) - determine who can submit jobs via at or batch at.deny (5) - determine who can submit jobs via at or batch btrfs-filesystem (8) - command group of btrfs that usually work on the whole filesystem docker-trust-signer (1) - Manage entities who can sign Docker images ipsec_newhostkey (8) - generate a new raw RSA authentication key for a host ipsec_showhostkey (8) - show host's authentication key w (1) - Show who is logged on and what they are doing. who (1) - show who is logged on who (1p) - display who is on the system whoami (1) - print effective userid
Presently, VirtualBox runs on Windows, Linux, Macintosh, and Solaris hosts and supports a large number of guest operating systems including but not limited to Windows (NT 4.0, 2000, XP, Server 2003, Vista, Windows 7, Windows 8), DOS/Windows 3.x, Linux (2.4, 2.6 and 3.x), Solaris and OpenSolaris, OS/2, and OpenBSD.