XARGS(1) COMMAND REFERENCE XARGS(1)
NAME
xargs - construct argument list(s) and execute command
SYNOPSIS
xargs [ -eeofstr ][ -ireplstr ][ -lnumber ][ -nnumber ][ -p
][ -ssize ][ -t ][ -x ] [command[initial-arguments]]
DESCRIPTION
Xargs combines the fixed initial-arguments with arguments
read from standard input to execute the specified command
one or more times. The number of arguments read for each
command invocation and the manner in which they are combined
are determined by the flags specified.
Command, which may be a shell file, is searched for, using
one's $PATH. If command is omitted, /bin/echo is used.
Arguments read in from standard input are defined to be
continuous strings of characters delimited by one or more
blanks, tabs, or newlines; empty lines are always discarded.
Blanks and tabs may be embedded as part of an argument if
escaped or quoted. Characters enclosed in quotes (single or
double) are taken literally, and the delimiting quotes are
removed. Outside of quoted strings a backslash (\) will
escape the next character.
Each argument list is constructed starting with the
initial-arguments, followed by some number of arguments read
from standard input (exception: see -i flag). Flags -i, -l,
and -n determine how arguments are selected for each command
invocation. When none of these flags are coded, the
initial-arguments are followed by arguments read
continuously from standard input until an internal buffer is
full, and then command is executed with the accumulated
arguments. This process is repeated until there are no more
arguments. When there are flag conflicts (for example, -l
vs. -n), the last flag has precedence.
Xargs will terminate if either it receives a return code of
-1 from, or if it cannot execute, command. When command is
a shell program, it should explicitly exit (see sh(1sh))
with an appropriate value to avoid accidentally returning
with -1.
OPTIONS
-eeofstr
Eofstr is taken as the logical end-of-file string.
Underscore (_) is assumed for the logical EOF string if
-e is not coded. The -e option with no eofstr coded
turns off the logical EOF string capability (underscore
is taken literally). Xargs reads standard input until
either end-of-file or the logical EOF string is
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XARGS(1) COMMAND REFERENCE XARGS(1)
encountered.
-ireplstr
Insert mode: command is executed for each line from
standard input, taking the entire line as a single
argument, inserting it in initial-arguments for each
occurrence of replstr. A maximum of five arguments in
initial-arguments may each contain one or more instances
of replstr. Blanks and tabs at the beginning of each
line are thrown away. Constructed arguments may not
grow larger than 255 characters, and option -x is also
forced. {} is assumed for replstr if not specified.
-lnumber
Command is executed for each nonempty number lines of
arguments from standard input. The last invocation of
command will be with fewer lines of arguments if fewer
than number remain. A line is considered to end with
the first newline unless the last character of the line
is a blank or a tab; a trailing blank/tab signals
continuation through the next nonempty line. If number
is omitted 1 is assumed. Option -x is forced.
-nnumber
Execute command using as many standard input arguments
as possible, up to number arguments maximum. Fewer
arguments will be used if their total size is greater
than size characters, and for the last invocation if
there are fewer than number arguments remaining. If
option -x is also coded, each number arguments must fit
in the size limitation, else xargs terminates execution.
-p Prompt mode: The user is asked whether to execute
command each invocation. Trace mode (-t) is turned on to
print the command instance to be executed, followed by a
?... prompt. A reply of y, meaning yes, (optionally
followed by anything), will execute the command;
anything else, including just a carriage return, skips
that particular invocation of command.
-ssize
The maximum total size of each argument list is set to
size characters; size must be a positive integer less
than or equal to 470. If -s is not coded, 470 is taken
as the default. Note that the character count for size
includes one extra character for each argument and the
count of characters in the command name.
-t Trace mode: The command and each constructed argument
list are echoed to file descriptor 2 just prior to their
execution.
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XARGS(1) COMMAND REFERENCE XARGS(1)
-x Causes xargs to terminate if any argument list would be
greater than size characters; -x is forced by the
options -i and -l. When none of the options -i, -l, or
-n are coded, the total length of all arguments must be
within the size limit.
EXAMPLES
The following will move all files from directory $1 to
directory $2, and echo each move command just before doing
it:
ls $1 | xargs -i -t mv $1/{} $2/{}
The following will combine the output of the parenthesized
commands onto one line, which is then echoed to the end-of-
file log:
(logname; date; echo $0 $*) | xargs >>log
The user is asked which files in the current directory are
to be archived and archives them into arch either one at a
time, or many at a time:
1. ls | xargs -p -l ar r arch
2. ls | xargs -p -l | xargs ar r arch
The following will execute diff(1) with successive pairs of
arguments originally typed as shell arguments:
echo $* | xargs -n2 diff
SEE ALSO
sh(1sh), echo(1), find(1).
Printed 10/17/86 3
%%index%%
na:72,90;
sy:162,411;
de:573,2320;
op:2893,593;3630,3111;6885,417;
ex:7302,883;
se:8185,120;
%%index%%000000000126