XARGS(1) | General Commands Manual | XARGS(1) |
xargs
— construct
argument list(s) and execute utility
xargs |
[-0oprt ] [-E
eofstr] [-I
replstr [-R
replacements] [-S
replsize]] [-J
replstr] [-L
number] [-n
number [-x ]]
[-P maxprocs]
[-s size]
[utility [argument ...]] |
The xargs
utility reads space, tab,
newline and end-of-file delimited strings from the standard input and
executes utility with the strings as arguments.
Any arguments specified on the command line are given to
utility upon each invocation, followed by some number
of the arguments read from the standard input of
xargs
. This is repeated until standard input is
exhausted.
Spaces, tabs and newlines may be embedded in arguments using single (`` ' '') or double (``"'') quotes or backslashes (``\''). Single quotes escape all non-single quote characters, excluding newlines, up to the matching single quote. Double quotes escape all non-double quote characters, excluding newlines, up to the matching double quote. Any single character, including newlines, may be escaped by a backslash.
The options are as follows:
-0
,
--null
xargs
to expect NUL (``\0'') characters as
separators, instead of spaces and newlines. This is expected to be used in
concert with the -print0
function in
find(1).-E
eofstr-I
replstr-R
flag is specified) arguments to utility with the
entire line of input. The resulting arguments, after replacement is done,
will not be allowed to grow beyond replsize (or 255
if no -S
flag is specified) bytes; this is
implemented by concatenating as much of the argument containing
replstr as possible, to the constructed arguments to
utility, up to replsize bytes.
The size limit does not apply to arguments to
utility which do not contain
replstr, and furthermore, no replacement will be
done on utility itself. Implies
-x
.-J
replstrxargs
will use the
data read from standard input to replace the first occurrence of
replstr instead of appending that data after all
other arguments. This option will not affect how many arguments will be
read from input (-n
), or the size of the
command(s) xargs
will generate
(-s
). The option just moves where those arguments
will be placed in the command(s) that are executed. The
replstr must show up as a distinct
argument to xargs
. It will
not be recognized if, for instance, it is in the middle of a quoted
string. Furthermore, only the first occurrence of the
replstr will be replaced. For example, the following
command will copy the list of files and directories which start with an
uppercase letter in the current directory to
destdir:
/bin/ls -1d [A-Z]* | xargs -J %
cp -Rp % destdir
-L
number-n
number,
--max-args=
number-s
option) exceeds the
specified size or there are fewer than
number arguments remaining for the last invocation
of utility. The current default value for
number is 5000.-o
xargs
to run an interactive application.-P
maxprocs,
--max-procs=
maxprocsxargs
will run as many processes as
possible.-p
,
--interactive
y
’ in the POSIX locale, causes the
command to be executed, any other response causes it to be skipped. No
commands are executed if the process is not attached to a terminal.-r
,
--no-run-if-empty
xargs
. The GNU version of
xargs
runs the utility
argument at least once, even if xargs
input is
empty, and it supports a -r
option to inhibit this
behavior. The FreeBSD version of
xargs
does not run the
utility argument on empty input, but it supports the
-r
option for command-line compatibility with GNU
xargs
, but the -r
option
does nothing in the FreeBSD version of
xargs
.-R
replacements-I
will do replacement in. If replacements is negative,
the number of arguments in which to replace is unbounded.-S
replsize-I
can
use for replacements. The default for replsize is
255.-s
size,
--max-chars=
sizeNULL
terminators) and the current environment will
be less than or equal to this number. The current default value for
size is ARG_MAX
- 4096.-t
,
--verbose
-x
,
--exit
xargs
to terminate immediately if a command
line containing number arguments will not fit in the
specified (or default) command line length.If utility is omitted, echo(1) is used.
Undefined behavior may occur if utility reads from the standard input.
If a command line cannot be assembled, or cannot be invoked, or if
an invocation of utility is terminated by a signal, or
an invocation of utility exits with a value of 255,
the xargs
utility stops processing input and exits
after all invocations of utility finish
processing.
In legacy mode, the -L
option treats all
newlines as end-of-line, regardless of whether the line is empty or ends
with a space. In addition, the -L
and
-n
options are not mutually-exclusive.
For more information about legacy mode, see compat(5).
The xargs
utility exits with a value of 0
if no error occurs. If utility cannot be found,
xargs
exits with a value of 127, otherwise if
utility cannot be executed,
xargs
exits with a value of 126. If any other error
occurs, xargs
exits with a value of 1.
Create a 3x3 matrix with numbers from 1 to 9. Every echo(1) instance receives three lines as arguments:
$ seq 1 9 | xargs -L3 echo 1 2 3 4 5 6 7 8 9
Duplicate every line from standard input:
$ echo -e "one\ntwo\nthree" | xargs -I % echo % % one one two two three three
Execute at most 2 concurrent instances of find(1) every one of them using one of the directories from the standard input:
ls -d /usr/local /opt | xargs -J % -P2 -n1 find % -name file
The xargs
utility is expected to be
IEEE Std 1003.2 (“POSIX.2”) compliant.
The -J
, -o
,
-P
, -R
and
-S
options are non-standard
FreeBSD extensions which may not be available on
other operating systems.
The xargs
utility appeared in PWB
UNIX.
If utility attempts to invoke another
command such that the number of arguments or the size of the environment is
increased, it risks execvp(3) failing
with E2BIG
.
The xargs
utility does not take multibyte
characters into account when performing string comparisons for the
-I
and -J
options, which may
lead to incorrect results in some locales.
September 21, 2020 | macOS 14.6 |