path: root/src/parset.pod

#!/usr/bin/perl -w

# SPDX-FileCopyrightText: 2021-2024 Ole Tange, http://ole.tange.dk and Free Software and Foundation, Inc.
# SPDX-License-Identifier: GFDL-1.3-or-later
# SPDX-License-Identifier: CC-BY-SA-4.0

=encoding utf8

=head1 NAME

parset - set shell variables in parallel


=head1 SYNOPSIS

B<parset> I<variablename> [options for GNU Parallel]

B<env_parset> I<variablename> [options for GNU Parallel]

=head1 DESCRIPTION

B<parset> is a shell function that puts the output from GNU
B<parallel> into shell variables.

B<env_parset> is a shell function that puts the output from
B<env_parallel> into shell variables.

The B<parset> and B<env_parset> functions are defined as part of
B<env_parallel>.

If I<variablename> is a single variable name, this will be treated as
the destination variable. If the variable is defined as an associative
array (using B<typeset -A myassoc>), this will be used. Otherwise the
variable will be made into a normal array.

If I<variablename> contains multiple names separated by ',' or space,
the names will be the destination variables. The number of names must
be at least the number of jobs.


=head1 OPTIONS

Same as GNU B<parallel>, but they are put I<after> the destination
variable.


=head1 SUPPORTED SHELLS

=head2 Bash/Zsh/Ksh/Mksh

=head3 Examples

Put output into B<myarray>:

  parset myarray seq 3 ::: 4 5 6
  echo "${myarray[1]}"

Put output into vars B<$seq, $pwd, $ls>:

  parset "seq pwd ls" ::: "seq 10" pwd ls
  echo "$ls"

Put output into vars B<$seq, $pwd, $ls>:

  into_vars=(seq pwd ls)
  parset "${into_vars[*]}" ::: "seq 10" pwd ls
  echo "$ls"

Put output into associative array B<myassoc> (not supported for mksh):

  typeset -A myassoc
  parset myassoc seq ::: 4 5 ::: 6 7
  echo "${myassoc[4 7]}"

The commands to run can be an array:

  cmd=("echo first" "echo '<<joe  \"double  space\"  cartoon>>'" "pwd")
  parset data ::: "${cmd[@]}"
  echo "${data[1]}"
  echo "${data[2]}"

B<parset> can read from stdin (standard input) if it is a file:

  parset res echo < parallel_input_file

but B<parset> can I<not> be part of a pipe. In particular this means
it cannot read from a pipe or write to a pipe:

  seq 10 | parset res echo Does not work

but must instead use a tempfile:

  seq 10 > parallel_input
  parset res echo :::: parallel_input
  echo "${res[1]}"
  echo "${res[9]}"

or a FIFO:

  mkfifo input_fifo
  seq 30 > input_fifo &
  parset res echo :::: input_fifo
  echo "${res[1]}"
  echo "${res[29]}"

or Bash/Zsh/Ksh process substitution:

  parset res echo :::: <(seq 100)
  echo "${res[1]}"
  echo "${res[99]}"


=head3 Installation

Put this in the relevant B<$HOME/.bashrc> or B<$HOME/.zshenv> or B<$HOME/.kshrc>:

  . `which env_parallel.bash`
  . `which env_parallel.zsh`
  source `which env_parallel.ksh` 

E.g. by doing:

  echo '. `which env_parallel.bash`' >> $HOME/.bashrc
  echo '. `which env_parallel.zsh`' >> $HOME/.zshenv
  echo 'source `which env_parallel.ksh`' >> $HOME/.kshrc

or by doing:

  env_parallel --install


=head2 ash/dash (FreeBSD's /bin/sh)

=head3 Examples

ash does not support arrays.

Put output into vars B<$seq, $pwd, $ls>:

  parset "seq pwd ls" ::: "seq 10" pwd ls
  echo "$ls"

B<parset> can read from stdin (standard input) if it is a file:

  parset res1,res2,res3 echo < parallel_input_file

but B<parset> can not be part of a pipe. In particular this means it
cannot read from a pipe or write to a pipe:

  seq 3 | parset res1,res2,res3 echo Does not work

but must instead use a tempfile:

  seq 3 > parallel_input
  parset res1,res2,res3 echo :::: parallel_input
  echo "$res1"
  echo "$res2"
  echo "$res3"

or a FIFO:

  mkfifo input_fifo
  seq 3 > input_fifo &
  parset res1,res2,res3 echo :::: input_fifo
  echo "$res1"
  echo "$res2"
  echo "$res3"

=head3 Installation

Put the relevant one of these into B<$HOME/.profile>:

  . `which env_parallel.sh`
  . `which env_parallel.ash`
  . `which env_parallel.dash`

E.g. by doing:

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

or by doing:

  env_parallel --install


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

Copyright (C) 2010-2024 Ole Tange, http://ole.tange.dk and Free
Software Foundation, Inc.


=head1 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/>.

=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 LICENSES/GFDL-1.3-or-later.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
LICENCES/CC-BY-SA-4.0.txt

=head1 DEPENDENCIES

B<parset> uses GNU B<parallel>.


=head1 SEE ALSO

B<parallel>(1), B<env_parallel>(1), B<bash>(1).


=cut