ENV_PARALLEL(1)

NAME
env_parallel - export environment to GNU parallel

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

DESCRIPTION
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) you are recommended only to transfer the environment that you need.

To help you do that, you can mark names that should not be transferred. This can be done with either --session or --record-env.

  # 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

Or:

  # 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

  # Optionally
  env_parallel --end-session

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

  Environment space
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.

OPTIONS
Same as GNU parallel in addition to these:

--end-session
    Undo last --session

--record-env
    Record all names currently defined to be ignored every time running env_parallel in the future.

--session
    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

SUPPORTED SHELLS

  Ash
Installation

Put this in $HOME/.profile:

  . env_parallel.ash

E.g. by doing:

  echo '. 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.

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

      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

functions
      ash cannot list defined functions - thus is not supported.

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

arrays
    Arrays are not supported by Ash.

  Bash
Installation

Put this in $HOME/.bashrc:

  . env_parallel.bash

E.g. by doing:

  echo '. 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.

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

      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

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

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

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

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.

  csh
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.

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

functions
    Not supported by csh.

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

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

  Dash
Installation

Put this in $HOME/.profile:

  . env_parallel.dash

E.g. by doing:

  echo '. 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.

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

      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

functions
      dash cannot list defined functions - thus is not supported.

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

arrays
      dash does not support arrays.

  fish
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.

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

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

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

arrays
    Arrays normally work, but fail intermitently.

      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

  ksh
Installation

Put this in $HOME/.kshrc:

  source env_parallel.ksh

E.g. by doing:

  echo 'source 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.

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

      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

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

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

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

  mksh
Installation

Put this in $HOME/.mkshrc:

  source env_parallel.mksh

E.g. by doing:

  echo 'source 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.

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

      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

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

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

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

  pdksh
Installation

Put this in $HOME/.profile:

  source env_parallel.pdksh

E.g. by doing:

  echo 'source 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.

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

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

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

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

  sh
Installation

Put this in $HOME/.profile:

  . env_parallel.sh

E.g. by doing:

  echo '. 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.

aliases
      sh does not support aliases.

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

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

arrays
      sh does not support arrays.

  tcsh
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.

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

functions
    Not supported by tcsh.

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

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

  Zsh
Installation

Put this in $HOME/.zshrc:

  . env_parallel.zsh

E.g. by doing:

  echo '. 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.

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

      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

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

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

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

EXIT STATUS
Same as GNU parallel.

AUTHOR
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.

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

Copyright (C) 2010-2025 Ole Tange, http://ole.tange.dk and Free Software Foundation, Inc.

LICENSE
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/>.

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

  Documentation license II
You are free:

to Share
    to copy, distribute and transmit the work

to Remix
    to adapt the work

Under the following conditions:

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).

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.

With the understanding that:

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

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.

Other Rights
    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.

Notice
    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

DEPENDENCIES
env_parallel uses GNU parallel.

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