DOKK / manpages / debian 12 / parallel / env_parallel.1.en
ENV_PARALLEL(1) parallel ENV_PARALLEL(1)

env_parallel - export environment to GNU parallel

env_parallel [--record-env|--session|--end-session]
[options for GNU Parallel]

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

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

env_parallel is 100 ms slower at startup than pure GNU parallel, and takes up to 30% longer to start a job (typically 15 ms).

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

  # Do --record-env into $PARALLEL_IGNORED_NAMES
  env_parallel --session
  # Define whatever you want to use
  myfunc() { myalias and functions $myvar work. $1.; }
  alias myalias='echo Aliases'
  myvar='and variables'
  # env_parallel will not export names in $PARALLEL_IGNORED_NAMES
  env_parallel -S localhost myfunc ::: Hooray

Or:

  # Record the "clean" environment (this only needs to be run once)
  env_parallel --record-env
  # Optionally edit ~/.parallel/ignored_vars (only needed once)
  # Define whatever you want to use
  myfunc() { myalias and functions $myvar work. $1.; }
  alias myalias='echo Aliases'
  myvar='and variables'
  # Use --env _ to only transfer the names not in the "empty" environment
  env_parallel --env _ -S localhost myfunc ::: Hooray

In csh --session is not supported:

  # Record the "clean" environment - this only needs to be run once
  env_parallel --record-env
  # Optionally edit ~/.parallel/ignored_vars - only needed once
  # Define whatever you want to use
  alias myalias 'echo Aliases $myvar \!*.'
  set myvar='and variables'
  # Use --env _ to only transfer the names not in the "empty" environment
  env_parallel --env _ -S localhost myalias ::: work

By default 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 env_parallel will fail if '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 env_parallel to fail.

Instead you can use --env to specify which variables, arrays, aliases and functions to export as this will only export those with the given name. Or follow the recommended usage in shown in DESCRIPTION.

Same as GNU parallel in addition to these:

Undo last --session
Record all names currently defined to be ignored every time running env_parallel in the future.
Ignore all names currently defined. Aliases, variables, arrays, and functions currently defined will not be transferred.

But names defined after running parallel --session will be transferred.

This is only valid in the running shell, and can be undone with parallel --end-session.

You can run multiple --session inside each other:

  env_parallel --session
  var=not
  # var is transferred
  env_parallel -Slocalhost 'echo var is $var' ::: ignored
  env_parallel --session
  # var is not transferred
  env_parallel -Slocalhost 'echo var is $var' ::: ignored
  env_parallel --end-session
  # var is transferred again
  env_parallel -Slocalhost 'echo var is $var' ::: ignored

Installation

Put this in $HOME/.profile:

  . `which env_parallel.ash`

E.g. by doing:

  echo '. `which env_parallel.ash`' >> $HOME/.profile

Supported use

--env is supported to export only the variable, or alias with the given name. Multiple --envs can be given.

--session is supported.

  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
  alias multiline='echo multiline
    echo aliases'
  env_parallel multiline ::: work
  env_parallel -S server multiline ::: work
  env_parallel --env multiline multiline ::: work
  env_parallel --env multiline -S server multiline ::: work
    
  ash cannot list defined functions - thus is not supported.
    
  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
Arrays are not supported by Ash.

Installation

Put this in $HOME/.bashrc:

  . `which env_parallel.bash`

E.g. by doing:

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

Supported use

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

--session is supported.

  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
  alias multiline='echo multiline
    echo aliases'
  env_parallel 'multiline {};
    echo but only when followed by a newline' ::: work
  env_parallel -S server 'multiline {};
    echo but only when followed by a newline' ::: work
  env_parallel --env multiline 'multiline {};
    echo but only when followed by a newline' ::: work
  env_parallel --env multiline -S server 'multiline {};
    echo but only when followed by a newline' ::: work
    
  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
    
  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
    
  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

BUGS

Due to a bug in Bash, aliases containing newlines must be followed by a newline in the command. Some systems are not affected by this bug, but will print a warning anyway.

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

Installation

Put this in $HOME/.cshrc:

  source `which env_parallel.csh`

E.g. by doing:

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

Supported use

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

  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
Not supported by csh.
  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
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

Installation

Put this in $HOME/.profile:

  . `which env_parallel.dash`

E.g. by doing:

  echo '. `which env_parallel.dash`' >> $HOME/.profile

Supported use

--env is supported to export only the variable, or alias with the given name. Multiple --envs can be given.

--session is supported.

  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
  alias multiline='echo multiline
    echo aliases'
  env_parallel multiline ::: work
  env_parallel -S server multiline ::: work
  env_parallel --env multiline multiline ::: work
  env_parallel --env multiline -S server multiline ::: work
    
  dash cannot list defined functions - thus is not supported.
    
  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
    
  dash does not support arrays.

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

Supported use

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

--session is supported.

  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
    
  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
    
  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
    
  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

Installation

Put this in $HOME/.kshrc:

  source `which env_parallel.ksh`

E.g. by doing:

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

Supported use

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

--session is supported.

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

Installation

Put this in $HOME/.mkshrc:

  source `which env_parallel.mksh`

E.g. by doing:

  echo 'source `which env_parallel.mksh`' >> $HOME/.mkshrc

Supported use

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

--session is supported.

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

Installation

Put this in $HOME/.profile:

  source `which env_parallel.pdksh`

E.g. by doing:

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

Supported use

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

--session is supported.

  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
    
  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
    
  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
    
  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

Installation

Put this in $HOME/.profile:

  . `which env_parallel.sh`

E.g. by doing:

  echo '. `which env_parallel.sh`' >> $HOME/.profile

Supported use

--env is supported to export only the variable, or alias with the given name. Multiple --envs can be given.

--session is supported.

  sh does not support aliases.
    
  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
    
  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
    
  sh does not support arrays.

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

Installation

Put this in $HOME/.tcshrc:

  source `which env_parallel.tcsh`

E.g. by doing:

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

Supported use

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

  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
Not supported by tcsh.
  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
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

Installation

Put this in $HOME/.zshrc:

  . `which env_parallel.zsh`

E.g. by doing:

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

Supported use

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

--session is supported.

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

Same as GNU parallel.

When using GNU env_parallel for a publication please cite:

O. Tange (2018): GNU Parallel 2018, March 2018, ISBN 9781387509881, DOI: 10.5281/zenodo.1146014.

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

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

Copyright (C) 2010-2022 Ole Tange, http://ole.tange.dk 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/>.

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 LICENSES/GFDL-1.3-or-later.txt.

You are free:

to copy, distribute and transmit the work
to adapt the work

Under the following conditions:

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

With the understanding that:

Any of the above conditions can be waived if you get permission from the copyright holder.
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.
In no way are any of the following rights affected by the license:
  • Your fair dealing or fair use rights, or other applicable copyright exceptions and limitations;
  • The author's moral rights;
  • Rights other persons may have either in the work itself or in how the work is used, such as publicity or privacy rights.
For any reuse or distribution, you must make clear to others the license terms of this work.

A copy of the full license is included in the file as LICENCES/CC-BY-SA-4.0.txt

env_parallel uses GNU parallel.

parallel(1), ash(1), bash(1), csh(1), dash(1), fish(1), ksh(1), pdksh(1) tcsh(1), zsh(1).

2022-12-18 20221122