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Ole Tange
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106
src/parallel
106
src/parallel
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@ -6,8 +6,7 @@ parallel - build and execute shell command lines from standard input in parallel
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=head1 SYNOPSIS
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B<parallel> [-0cdEfghiIkmnpqrtuUvVX] [B<-I> str] [B<-j> num] [--silent]
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[command [arguments]] [< list_of_arguments]
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B<parallel> [options] [I<command> [arguments]] [< list_of_arguments]
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=head1 DESCRIPTION
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@ -27,23 +26,21 @@ GNU B<parallel> makes sure output from the commands is the same output as
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you would get had you run the commands sequentially. This makes it
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possible to use output from GNU B<parallel> as input for other programs.
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For each line of input GNU B<parallel> will execute B<command> with the
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line as arguments. If no B<command> is given the line of input is
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executed. GNU B<parallel> can often be used as a substitute for B<xargs>
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or B<cat | sh>.
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Several lines will be run in parallel.
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For each line of input GNU B<parallel> will execute I<command> with
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the line as arguments. If no I<command> is given, the line of input is
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executed. Several lines will be run in parallel. GNU B<parallel> can
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often be used as a substitute for B<xargs> or B<cat | sh>.
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=over 9
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=item I<command>
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Command to execute. If B<command> or the following arguments contain
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Command to execute. If I<command> or the following arguments contain
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{} every instance will be substituted with the input line. Setting a
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command also invokes B<-f>.
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If B<command> is given, GNU B<parallel> will behave similar to B<xargs>. If
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B<command> is not given GNU B<parallel> will behave similar to B<cat | sh>.
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If I<command> is given, GNU B<parallel> will behave similar to B<xargs>. If
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I<command> is not given GNU B<parallel> will behave similar to B<cat | sh>.
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=item B<{}>
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@ -56,12 +53,15 @@ changed with B<-I>.
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=item B<{.}>
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Input line without extension. This is a specialized replacement string
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with the extension removed. It will remove from the last B<.> till the
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end of line of each input line and replace {.} with the
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remaining. E.g. I<foo.jpg> becomes I<foo>. If the input line does
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not contain B<.> it will remain unchanged.
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with the extension removed. If the input line contains B<.> after the
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last B</> the last B<.> till the end of the string will be removed and
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B<{.}> will be replaced with the remaining. E.g. I<foo.jpg> becomes
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I<foo>, I<subdir/foo.jpg> becomes I<subdir/foo>, I<sub.dir/foo.jpg>
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becomes I<sub.dir/foo>, I<sub.dir/bar> remains I<sub.dir/bar>. If the
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input line does not contain B<.> it will remain unchanged.
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{.} can be used the same places as {}.
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B<{.}> can be used the same places as B<{}>. The replacement string
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B<{.}> can be changed with B<-U>.
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=item B<--null>
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@ -84,18 +84,18 @@ Otherwise, stdin is redirected from /dev/null.
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=item B<--cleanup>
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Remove transfered files. B<--cleanup> will remove the transfered files
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Remove transferred files. B<--cleanup> will remove the transferred files
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on the remote server after processing is done.
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find log -name '*gz' | parallel \
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--sshlogin server.example.com --transfer --return {.}.bz2 \
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--cleanup "zcat {} | bzip -9 >{.}.bz2"
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With B<--transfer> the file transfered to the remote server will be
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With B<--transfer> the file transferred to the remote server will be
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removed on the remote server. Directories created will not be removed
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- even if they are empty.
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With B<--return> the file transfered from the remote server will be
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With B<--return> the file transferred from the remote server will be
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removed on the remote server. Directories created will not be removed
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- even if they are empty.
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@ -108,7 +108,7 @@ B<--cleanup> is ignored when not used with B<--transfer> or B<--return>.
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Line is a command. The input line contains more than one argument or
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the input line needs to be evaluated by the shell. This is the default
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if B<command> is not set. Can be reversed with B<-f>.
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if I<command> is not set. Can be reversed with B<-f>.
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=item B<--delimiter> I<delim>
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@ -151,7 +151,7 @@ B<-E> nor B<-e> is used, no end of file string is used.
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Line is a filename. The input line contains a filename that will be
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quoted so it is not evaluated by the shell. This is the default if
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B<command> is set. Can be reversed with B<-c>.
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I<command> is set. Can be reversed with B<-c>.
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=item B<--group>
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@ -205,7 +205,7 @@ Run up to N jobs in parallel. 0 means as many as possible. Default is 9.
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Add N to the number of CPU cores. Run this many jobs in parallel. For
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compute intensive jobs B<-j> +0 is useful as it will run
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number-of-cpu-cores jobs in parallel. See also
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--use-cpus-instead-of-cores.
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B<--use-cpus-instead-of-cores>.
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=item B<--jobs> I<-N>
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@ -218,7 +218,7 @@ number-of-cpu-cores jobs in parallel. See also
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Subtract N from the number of CPU cores. Run this many jobs in parallel.
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If the evaluated number is less than 1 then 1 will be used. See also
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--use-cpus-instead-of-cores.
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B<--use-cpus-instead-of-cores>.
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=item B<--jobs> I<N>%
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@ -231,7 +231,7 @@ If the evaluated number is less than 1 then 1 will be used. See also
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Multiply N% with the number of CPU cores. Run this many jobs in parallel.
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If the evaluated number is less than 1 then 1 will be used. See also
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--use-cpus-instead-of-cores.
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B<--use-cpus-instead-of-cores>.
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=item B<--keeporder>
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@ -267,7 +267,7 @@ Print the number of physical CPUs and exit (used by GNU B<parallel>
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itself to determine the number of physical CPUs on remote machines).
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=item B<--number-of-cores> (not implemented)
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=item B<--number-of-cores>
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Print the number of cores and exit (used by GNU B<parallel> itself to determine the
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number of cores on remote machines).
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@ -286,7 +286,7 @@ with 'y' or 'Y'. Implies B<-t>.
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=item B<-q>
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Quote B<command>. This will quote the command line so special
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Quote I<command>. This will quote the command line so special
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characters are not interpreted by the shell. See the section
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QUOTING. Most people will never need this. Quoting is disabled by
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default.
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@ -302,7 +302,7 @@ If the standard input only contains whitespace, do not run the command.
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Transfer files from remote servers. B<--return> is used with
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B<--sshlogin> when the arguments are files on the remote servers. When
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processing is done the file I<filename> will be transfered
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processing is done the file I<filename> will be transferred
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from the remote server using B<rsync> and will be put relative to
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the default login dir. E.g.
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@ -320,7 +320,7 @@ This will transfer the file I</tmp/foo/bar.out> from the server
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I<server.example.com> to the file I</tmp/foo/bar.out> after running
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B<touch /tmp/foo/bar.out> on I<server.example.com>.
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Multiple files can be transfered by repeating the options multiple
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Multiple files can be transferred by repeating the options multiple
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times:
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echo /tmp/foo/bar.txt | \
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@ -378,6 +378,8 @@ For examples: see B<--sshloginfile>.
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The remote host must have GNU B<parallel> installed.
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B<--sshlogin> is known to cause problems with B<-m> and B<-X>.
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=item B<--sshloginfile> I<filename> (beta testing)
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@ -393,7 +395,9 @@ lines. Empty lines and lines starting with '#' are ignored. Example:
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4/ssh -p 2222 quadserver.example.net
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# Use a different ssh program
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myssh -p 2222 -l compute hexacpu.example.net
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/usr/local/bin/myssh -p 2222 -l compute hexacpu.example.net
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# Use a different ssh program with default number of cores
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//usr/local/bin/myssh -p 2222 -l compute hexacpu.example.net
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# Use a different ssh program with 6 cores
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6//usr/local/bin/myssh -p 2222 -l compute hexacpu.example.net
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# Assume 16 cores on the local machine
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16/:
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@ -418,8 +422,8 @@ See also B<-v>.
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=item B<--transfer>
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Transfer files to remote servers. B<--transfer> is used with
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B<--sshlogin> when the arguments are files and should be transfered to
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the remote servers. The files will be transfered using B<rsync> and
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B<--sshlogin> when the arguments are files and should be transferred to
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the remote servers. The files will be transferred using B<rsync> and
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will be put relative to the default login dir. E.g.
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echo foo/bar.txt | parallel \
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@ -445,7 +449,7 @@ B<--transfer> is ignored when used with B<--sshlogin :> or when not used with B<
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Transfer, Return, Cleanup. Short hand for:
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--transfer --return filename --cleanup
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B<--transfer> B<--return> I<filename> B<--cleanup>
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=item B<--ungroup>
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@ -494,19 +498,19 @@ Print the version GNU B<parallel> and exit.
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=item B<-m>
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Multiple. Insert as many arguments as the command line length
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permits. If {} is not used the arguments will be appended to the line.
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If {} is used multiple times each {} will be replaced with all the
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arguments.
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permits. If B<{}> is not used the arguments will be appended to the
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line. If B<{}> is used multiple times each B<{}> will be replaced
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with all the arguments.
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Support for B<-m> with B<--sshlogin> is limited and may fail.
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=item B<-X>
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xargs with context replace. This works like B<-m> except if {} is part
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xargs with context replace. This works like B<-m> except if B<{}> is part
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of a word (like I<pic{}.jpg>) then the whole word will be
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repeated. Normally B<-X> will do the right thing, whereas B<-m> can
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give surprising results if {} is used as part of a word.
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give surprising results if B<{}> is used as part of a word.
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Support for B<-X> with B<--sshlogin> is limited and may fail.
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@ -577,7 +581,7 @@ To do it recursively use B<find>:
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B<find . -name '*.jpg' | parallel -j +0 convert -geometry 120 {} {}_thumb.jpg>
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Notice how the argument has to start with {} as {} will include path
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Notice how the argument has to start with B<{}> as B<{}> will include path
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(e.g. running B<convert -geometry 120 ./foo/bar.jpg
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thumb_./foo/bar.jpg> would clearly be wrong). The command will
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generate files like ./foo/bar.jpg_thumb.jpg.
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@ -617,15 +621,15 @@ B<ls | parallel '(echo -n {}" "; ls {}|wc -l) >> B<{}.dir'>
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=head1 EXAMPLE: Removing file extension when processing files
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When processing files removing the file extension using {.} is often
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useful.
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When processing files removing the file extension using B<{.}> is
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often useful.
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Create a directory for each zip-file and unzip it in that dir:
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B<ls *zip | parallel 'mkdir {.}; cd {.}; unzip ../{}'>
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Recompress all .gz files in current directory using B<bzip2> running 1
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job per CPU in parallel:
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job per CPU core in parallel:
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B<ls *.gz | parallel -j+0 "zcat {} | bzip2 >>B<{.}.bz2 && rm {}">
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@ -691,7 +695,7 @@ B<(echo foss.org.my; echo debian.org; echo freenetproject.org) | parallel -u tra
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Normally the output of a job will be printed as soon as it
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completes. Sometimes you want the order of the output to remain the
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same as the order of the input. This is often important, if the output
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is used for input for another system. B<-k> will make sure the order of
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is used as input for another system. B<-k> will make sure the order of
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output will be in the same order as input even if later jobs end
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before earlier jobs.
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@ -780,25 +784,25 @@ I<$HOME/logs>. On I<server.example.com> the file will be recompressed
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using B<zcat> and B<bzip2> resulting in the corresponding file with
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I<.gz> replaced with I<.bz2>.
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If you want the file to be transfered back to the local machine add
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If you want the file to be transferred back to the local machine add
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I<--return {.}.bz2>:
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find logs/ -name '*.gz' | \
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parallel --sshlogin server.example.com \
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--transfer --return {.}.bz2 "zcat {} | bzip2 -9 >{.}.bz2"
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After the recompressing is done the I<.bz2>-file is transfered back to
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After the recompressing is done the I<.bz2>-file is transferred back to
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the local machine and put next to the original I<.gz>-file.
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If you want to delete the transfered files on the remote machine add
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I<--cleanup>. This will remove both the file transfered to the remote
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machine and the files transfered from the remote machine:
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If you want to delete the transferred files on the remote machine add
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I<--cleanup>. This will remove both the file transferred to the remote
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machine and the files transferred from the remote machine:
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find logs/ -name '*.gz' | \
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parallel --sshlogin server.example.com \
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--transfer --return {.}.bz2 --cleanup "zcat {} | bzip2 -9 >{.}.bz2"
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If you want run one several servers add the servers to I<--sshlogin>
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If you want run on several servers add the servers to I<--sshlogin>
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either using ',' or multiple I<--sshlogin>:
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find logs/ -name '*.gz' | \
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@ -852,7 +856,7 @@ To run 100 processes simultaneously do:
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B<parallel -j 100 < jobs_to_run>
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As there is not a B<command> the option B<-c> is default because the
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As there is not a I<command> the option B<-c> is default because the
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jobs needs to be evaluated by the shell.
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@ -888,7 +892,7 @@ B<sh: -c: line 0: syntax error near unexpected token>
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then you might try using B<-q>.
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If you are using B<bash> process substitution like B<<(cat foo)> then
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you may try B<-q> and prepending B<command> with B<bash -c>:
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you may try B<-q> and prepending I<command> with B<bash -c>:
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B<ls | parallel -q bash -c 'wc -c <(echo {})'>
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@ -962,6 +966,8 @@ B<xargs> has no support for keeping the order of the output, therefore
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if running jobs in parallel using B<xargs> the output of the second
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job cannot be postponed till the first job is done.
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B<xargs> has no support for running jobs on remote machines.
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B<xargs> has no support for context replace, so you will have to create the
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arguments.
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