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.TH parallel 1 2009-07-02 "" ""
.SH NAME
parallel \- run programs in parallel
.SH SYNOPSIS
'nh
.fi
.ad l
\fBparallel\fR \kx
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[options] [command] \fB--\fR [argument ...]
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.ad b
'hy
'nh
.fi
.ad l
\fBparallel\fR \kx
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[options] \fB--\fR [command ...]
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'hy
.SH DESCRIPTION
\fBparallel\fR runs the specified command,
passing it a single one of the specified arguments. This is
repeated for each argument. Jobs may be run in
parallel. The default is to run one job per CPU.
.PP
If no command is specified before the --,
the commands after it are instead run in parallel.
.SH OPTIONS
.TP 
\*(T<\fB\-j maxjobs\fR\*(T>
Use to limit the number of jobs
that are run at the same time.
.TP 
\*(T<\fB\-l maxload\fR\*(T>
Avoid starting new jobs when
the system's load average is not below
the specified limit.
.TP 
\*(T<\fB\-i\fR\*(T>
Normally the command is passed the
argument at the end of its command line. With
this option, the first instance of "{}" in
the command is replaced with the argument.
.TP 
\*(T<\fB\-n\fR\*(T>
Number of arguments to pass to a
command at a time. Default is 1.
Incompatible with -i
.SH EXAMPLE
'nh
.fi
.ad l
\fBparallel sh -c "echo hi; sleep 2; echo bye" -- 1 2 3\fR \kx
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.PP
This runs three subshells that each print a message, delay,
and print another message. If your system has multiple
CPUs, parallel will run some of the jobs in parallel,
which should be clear from the order the messages are
output.
.PP
'nh
.fi
.ad l
\fBparallel -j 3 ufraw -o processed -- *.NEF\fR \kx
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'hy
.PP
This runs three ufraw processes at the same time until
all of the NEF files have been processed.
.PP
'nh
.fi
.ad l
\fBparallel -j 3 -- ls df "echo hi"\fR \kx
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'hy
.PP
This runs three independent commands in parallel.
.SH "EXIT STATUS"
Its exit status is the combination of the exit statuses of each
command ran, ORed together. (Thus, if any one command
exits nonzero, \fBparallel\fR as a whole will exit nonzero.)