XARGS(1) General Commands Manual XARGS(1)
xargs - construct argument list(s) and execute utility
xargs [-0oprt] [-E eofstr] [-I replstr [-R replacements]] [-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 the specified utility with
the strings as arguments.
Any arguments specified on the command line are given to the utility upon
each invocation, followed by some number of the arguments read from
standard input. The utility is repeatedly executed one or more times
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 Change xargs to expect NUL (`\0') characters as separators,
instead of spaces and newlines. The quoting mechanisms described
above are not performed. This option is expected to be used in
concert with the -print0 function in find(1).
Use eofstr as a logical EOF marker.
Execute utility for each input line, replacing one or more
occurrences of replstr in up to replacements (or 5 if no -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 255 bytes; this is implemented by
concatenating as much of the argument containing replstr as
possible, to the constructed arguments to utility, up to 255
bytes. The 255 byte 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.
If this option is specified, xargs 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 effect 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
Call utility for every number of non-empty lines read. A line
ending in unescaped white space and the next non-empty line are
considered to form one single line. If EOF is reached and fewer
than number lines have been read then utility will be called with
the available lines.
Set the maximum number of arguments taken from standard input for
each invocation of utility. An invocation of utility will use
less than number standard input arguments if the number of bytes
accumulated (see the -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
-o Reopen stdin as /dev/tty in the child process before executing
the command. This is useful if you want xargs to run an
Parallel mode: run at most maxprocs invocations of utility at
-p Echo each command to be executed and ask the user whether it
should be executed. An affirmative response, `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.
Specify the maximum number of arguments that -I will do
replacement in. If replacements is negative, the number of
arguments in which to replace is unbounded.
-r Do not run the command if there are no arguments. Normally the
command is executed at least once even if there are no arguments.
Set the maximum number of bytes for the command line length
provided to utility. The sum of the length of the utility name,
the arguments passed to utility (including NUL 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 Echo the command to be executed to standard error immediately
before it is executed.
-x Force xargs to terminate immediately if a command line containing
number arguments will not fit in the specified (or default)
command line length.
If no utility is specified, echo(1) is used.
Undefined behavior may occur if utility reads from the standard input.
The xargs utility exits immediately (without processing any further
input) if a command line cannot be assembled, utility cannot be invoked,
an invocation of utility is terminated by a signal, or an invocation of
utility exits with a value of 255.
xargs exits with one of the following values:
0 All invocations of utility returned a zero exit status.
123 One or more invocations of utility returned a nonzero exit
124 The utility exited with a 255 exit status.
125 The utility was killed or stopped by a signal.
126 The utility was found but could not be executed.
127 The utility could not be found.
1 Some other error occurred.
echo(1), find(1), execvp(3)
The xargs utility is compliant with the IEEE Std 1003.1-2008
The flags [-IL] are marked by IEEE Std 1003.1-2008 (``POSIX.1'') as being
an X/Open System Interfaces option.
The flags [-0JoPRr] are extensions to IEEE Std 1003.1-2008 (``POSIX.1'').
The meanings of the 123, 124, and 125 exit values were taken from GNU
The xargs command 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.
OpenBSD 5.9 June 4, 2014 OpenBSD 5.9
[Unix Hosting |
[Engineering & Automation |
Software Development |