parallel/src/env_parallel.pod

#!/usr/bin/perl -w

=encoding utf8

=head1 NAME

env_parallel - export environment to GNU parallel


=head1 SYNOPSIS

B<env_parallel> [options for GNU Parallel]


=head1 DESCRIPTION

B<env_parallel> is a shell function that exports the current
environment to GNU B<parallel>.

If the shell function is not loaded, a dummy script will be run
instead that explains how to install the function.

B<env_parallel> is beta quality and not production ready, but please
use it for everyday use and report bugs.

B<env_parallel> is 0.1 sec slower at startup than pure GNU
B<parallel>, and takes up to 15 ms to start a job.

Due to the problem with environment space (see below) the recommended
usage is:

  # Run once to record the "empty" environment
  env_parallel --record-env

  # Define whatever you want to use
  alias myalias=echo
  myvar=it
  myfunc() { myalias $1 $myvar works.; }

  # Use --env _ to only transfer the names not in the "empty" environment
  env_parallel --env _ -S localhost myfunc ::: Yay,

In B<csh>:

  # Run once to record the "empty" environment
  env_parallel --record-env

  # Define whatever you want to use
  alias myalias 'echo \!* $myvar works.'
  set myvar=it

  # Use --env _ to only transfer the names not in the "empty" environment
  env_parallel --env _ -S localhost myalias ::: Yay,


=head2 Environment space

By default B<env_parallel> will export all environment variables,
arrays, aliases, functions and shell options (see details for the
individual shells below).

But this only works if the size of the current environment is smaller
than the maximal length of a command and smaller than half of the max
if running remotely. E.g. The max size of Bash's command is 128 KB, so
B<env_parallel> will fail if B<set | wc -c> is bigger than 128
KB. Technically the limit is in execve(1) which IPC::open3 uses.

Bash completion functions are well-known for taking up well over 128
KB of environment space and the primary reason for causing
B<env_parallel> to fail.

Instead you can use B<--env> to specify which variables, arrays,
aliases and functions to export as this will only export those with
the given name.


=head1 OPTIONS

Same as GNU B<parallel>.


=head1 SUPPORTED SHELLS

=head2 Bash

B<--env> is supported to export only the variable, alias, function, or
array with the given name. Multiple B<--env>s can be given.

Installation

Put this in $HOME/.bashrc:

  . `which env_parallel.bash`

E.g. by doing:

  echo '. `which env_parallel.bash`' >> $HOME/.bashrc

=over 8

=item aliases

  alias myecho='echo aliases'
  env_parallel myecho ::: work
  env_parallel -S server myecho ::: work
  env_parallel --env myecho myecho ::: work
  env_parallel --env myecho -S server myecho ::: work

=item functions

  myfunc() { echo functions $*; }
  env_parallel myfunc ::: work
  env_parallel -S server myfunc ::: work
  env_parallel --env myfunc myfunc ::: work
  env_parallel --env myfunc -S server myfunc ::: work

=item variables

  myvar=variables
  env_parallel echo '$myvar' ::: work
  env_parallel -S server echo '$myvar' ::: work
  env_parallel --env myvar echo '$myvar' ::: work
  env_parallel --env myvar -S server echo '$myvar' ::: work

=item arrays

  myarray=(arrays work, too)
  env_parallel -k echo '${myarray[{}]}' ::: 0 1 2
  env_parallel -k -S server echo '${myarray[{}]}' ::: 0 1 2
  env_parallel -k --env myarray echo '${myarray[{}]}' ::: 0 1 2
  env_parallel -k --env myarray -S server echo '${myarray[{}]}' ::: 0 1 2

=back


=head2 csh

B<--env> is supported to export only the variable, alias, or
array with the given name. Multiple B<--env>s can be given.

B<env_parallel> for B<csh> breaks B<$PARALLEL>, so do not use
B<$PARALLEL>.

Installation

Put this in $HOME/.cshrc:

  source `which env_parallel.csh`

E.g. by doing:

  echo 'source `which env_parallel.csh`' >> $HOME/.cshrc

=over 8

=item aliases

  alias myecho 'echo aliases'
  env_parallel myecho ::: work
  env_parallel -S server myecho ::: work
  env_parallel --env myecho myecho ::: work
  env_parallel --env myecho -S server myecho ::: work

=item functions

Not supported by B<csh>.

=item variables

  set myvar=variables
  env_parallel echo '$myvar' ::: work
  env_parallel -S server echo '$myvar' ::: work
  env_parallel --env myvar echo '$myvar' ::: work
  env_parallel --env myvar -S server echo '$myvar' ::: work

=item arrays with no special chars

  set myarray=(arrays work, too)
  env_parallel -k echo \$'{myarray[{}]}' ::: 1 2 3
  env_parallel -k -S server echo \$'{myarray[{}]}' ::: 1 2 3
  env_parallel -k --env myarray echo \$'{myarray[{}]}' ::: 1 2 3
  env_parallel -k --env myarray -S server echo \$'{myarray[{}]}' ::: 1 2 3

=back


=head2 fish

B<--env> is supported to export only the variable, alias, function, or
array with the given name. Multiple B<--env>s can be given.

Installation

Put this in $HOME/.config/fish/config.fish:

  source (which env_parallel.fish)

E.g. by doing:

  echo 'source (which env_parallel.fish)' >> $HOME/.config/fish/config.fish

=over 8

=item aliases

  alias myecho 'echo aliases'
  env_parallel myecho ::: work
  env_parallel -S server myecho ::: work
  env_parallel --env myecho myecho ::: work
  env_parallel --env myecho -S server myecho ::: work

=item functions

  function myfunc
    echo functions $argv
  end
  env_parallel myfunc ::: work
  env_parallel -S server myfunc ::: work
  env_parallel --env myfunc myfunc ::: work
  env_parallel --env myfunc -S server myfunc ::: work

=item variables

  set myvar variables
  env_parallel echo '$myvar' ::: work
  env_parallel -S server echo '$myvar' ::: work
  env_parallel --env myvar echo '$myvar' ::: work
  env_parallel --env myvar -S server echo '$myvar' ::: work

=item arrays

  set myarray arrays work, too
  env_parallel -k echo '$myarray[{}]' ::: 1 2 3
  env_parallel -k -S server echo '$myarray[{}]' ::: 1 2 3
  env_parallel -k --env myarray echo '$myarray[{}]' ::: 1 2 3
  env_parallel -k --env myarray -S server echo '$myarray[{}]' ::: 1 2 3

=back


=head2 ksh

B<--env> is supported to export only the variable, alias, function, or
array with the given name. Multiple B<--env>s can be given.

Installation

Put this in $HOME/.kshrc:

  source `which env_parallel.ksh`

E.g. by doing:

  echo 'source `which env_parallel.ksh`' >> $HOME/.kshrc

=over 8

=item aliases

  alias myecho='echo aliases'
  env_parallel myecho ::: work
  env_parallel -S server myecho ::: work
  env_parallel --env myecho myecho ::: work
  env_parallel --env myecho -S server myecho ::: work

=item functions

  myfunc() { echo functions $*; }
  env_parallel myfunc ::: work
  env_parallel -S server myfunc ::: work
  env_parallel --env myfunc myfunc ::: work
  env_parallel --env myfunc -S server myfunc ::: work

=item variables

  myvar=variables
  env_parallel echo '$myvar' ::: work
  env_parallel -S server echo '$myvar' ::: work
  env_parallel --env myvar echo '$myvar' ::: work
  env_parallel --env myvar -S server echo '$myvar' ::: work

=item arrays

  myarray=(arrays work, too)
  env_parallel -k echo '${myarray[{}]}' ::: 0 1 2
  env_parallel -k -S server echo '${myarray[{}]}' ::: 0 1 2
  env_parallel -k --env myarray echo '${myarray[{}]}' ::: 0 1 2
  env_parallel -k --env myarray -S server echo '${myarray[{}]}' ::: 0 1 2

=back


=head2 pdksh

B<--env> is supported to export only the variable, alias, function, or
array with the given name. Multiple B<--env>s can be given.

Installation

Put this in $HOME/.profile:

  source `which env_parallel.pdksh`

E.g. by doing:

  echo 'source `which env_parallel.pdksh`' >> $HOME/.profile

=over 8

=item aliases

  alias myecho="echo aliases";
  env_parallel myecho ::: work;
  env_parallel -S server myecho ::: work;
  env_parallel --env myecho myecho ::: work;
  env_parallel --env myecho -S server myecho ::: work

=item functions

  myfunc() { echo functions $*; };
  env_parallel myfunc ::: work;
  env_parallel -S server myfunc ::: work;
  env_parallel --env myfunc myfunc ::: work;
  env_parallel --env myfunc -S server myfunc ::: work

=item variables

  myvar=variables;
  env_parallel echo "\$myvar" ::: work;
  env_parallel -S server echo "\$myvar" ::: work;
  env_parallel --env myvar echo "\$myvar" ::: work;
  env_parallel --env myvar -S server echo "\$myvar" ::: work

=item arrays

  myarray=(arrays work, too);
  env_parallel -k echo "\${myarray[{}]}" ::: 0 1 2;
  env_parallel -k -S server echo "\${myarray[{}]}" ::: 0 1 2;
  env_parallel -k --env myarray echo "\${myarray[{}]}" ::: 0 1 2;
  env_parallel -k --env myarray -S server echo "\${myarray[{}]}" ::: 0 1 2

=back


=head2 tcsh

B<--env> is supported to export only the variable, alias, or
array with the given name. Multiple B<--env>s can be given.

B<env_parallel> for B<tcsh> breaks B<$PARALLEL>, so do not use
B<$PARALLEL>.

Installation

Put this in $HOME/.tcshrc:

  source `which env_parallel.tcsh`

E.g. by doing:

  echo 'source `which env_parallel.tcsh`' >> $HOME/.tcshrc

=over 8

=item aliases

  alias myecho 'echo aliases'
  env_parallel myecho ::: work
  env_parallel -S server myecho ::: work
  env_parallel --env myecho myecho ::: work
  env_parallel --env myecho -S server myecho ::: work

=item functions

Not supported by B<tcsh>.

=item variables

  set myvar=variables
  env_parallel echo '$myvar' ::: work
  env_parallel -S server echo '$myvar' ::: work
  env_parallel --env myvar echo '$myvar' ::: work
  env_parallel --env myvar -S server echo '$myvar' ::: work

=item arrays with no special chars

  set myarray=(arrays work, too)
  env_parallel -k echo \$'{myarray[{}]}' ::: 1 2 3
  env_parallel -k -S server echo \$'{myarray[{}]}' ::: 1 2 3
  env_parallel -k --env myarray echo \$'{myarray[{}]}' ::: 1 2 3
  env_parallel -k --env myarray -S server echo \$'{myarray[{}]}' ::: 1 2 3

=back


=head2 Zsh

B<--env> is supported to export only the variable, alias, function, or
array with the given name. Multiple B<--env>s can be given.

Installation

Put this in $HOME/.zshrc:

  . `which env_parallel.zsh`

E.g. by doing:

  echo '. `which env_parallel.zsh`' >> $HOME/.zshenv

=over 8

=item aliases

  alias myecho='echo aliases'
  env_parallel myecho ::: work
  env_parallel -S server myecho ::: work
  env_parallel --env myecho myecho ::: work
  env_parallel --env myecho -S server myecho ::: work

=item functions

  myfunc() { echo functions $*; }
  env_parallel myfunc ::: work
  env_parallel -S server myfunc ::: work
  env_parallel --env myfunc myfunc ::: work
  env_parallel --env myfunc -S server myfunc ::: work

=item variables

  myvar=variables
  env_parallel echo '$myvar' ::: work
  env_parallel -S server echo '$myvar' ::: work
  env_parallel --env myvar echo '$myvar' ::: work
  env_parallel --env myvar -S server echo '$myvar' ::: work

=item arrays

  myarray=(arrays work, too)
  env_parallel -k echo '${myarray[{}]}' ::: 1 2 3
  env_parallel -k -S server echo '${myarray[{}]}' ::: 1 2 3
  env_parallel -k --env myarray echo '${myarray[{}]}' ::: 1 2 3
  env_parallel -k --env myarray -S server echo '${myarray[{}]}' ::: 1 2 3

=back


=head1 EXIT STATUS

Same as GNU B<parallel>.


=head1 AUTHOR

When using GNU B<parallel> for a publication please cite:

O. Tange (2011): GNU Parallel - The Command-Line Power Tool, ;login:
The USENIX Magazine, February 2011:42-47.

This helps funding further development; and it won't cost you a cent.
If you pay 10000 EUR you should feel free to use GNU Parallel without citing.

Copyright (C) 2007-10-18 Ole Tange, http://ole.tange.dk

Copyright (C) 2008,2009,2010 Ole Tange, http://ole.tange.dk

Copyright (C) 2010,2011,2012,2013,2014,2015,2016 Ole Tange,
http://ole.tange.dk and Free Software Foundation, Inc.

Parts of the manual concerning B<xargs> compatibility is inspired by
the manual of B<xargs> from GNU findutils 4.4.2.


=head1 LICENSE

Copyright (C) 2016
Ole Tange and Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
at your option any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

=head2 Documentation license I

Permission is granted to copy, distribute and/or modify this documentation
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts.  A copy of the license is included in the file fdl.txt.

=head2 Documentation license II

You are free:

=over 9

=item B<to Share>

to copy, distribute and transmit the work

=item B<to Remix>

to adapt the work

=back

Under the following conditions:

=over 9

=item B<Attribution>

You must attribute the work in the manner specified by the author or
licensor (but not in any way that suggests that they endorse you or
your use of the work).

=item B<Share Alike>

If you alter, transform, or build upon this work, you may distribute
the resulting work only under the same, similar or a compatible
license.

=back

With the understanding that:

=over 9

=item B<Waiver>

Any of the above conditions can be waived if you get permission from
the copyright holder.

=item B<Public Domain>

Where the work or any of its elements is in the public domain under
applicable law, that status is in no way affected by the license.

=item B<Other Rights>

In no way are any of the following rights affected by the license:

=over 2

=item *

Your fair dealing or fair use rights, or other applicable
copyright exceptions and limitations;

=item *

The author's moral rights;

=item *

Rights other persons may have either in the work itself or in
how the work is used, such as publicity or privacy rights.

=back

=back

=over 9

=item B<Notice>

For any reuse or distribution, you must make clear to others the
license terms of this work.

=back

A copy of the full license is included in the file as cc-by-sa.txt.


=head1 DEPENDENCIES

B<env_parallel> uses GNU B<parallel>.


=head1 SEE ALSO

B<parallel>(1), 

B<bash>(1), B<csh>(1), B<fish>(1), B<ksh>(1), B<pdksh>(1) B<tcsh>(1),
B<zsh>(1).


=cut