parallel/src/parset.pod

#!/usr/bin/perl -w

=encoding utf8

=head1 NAME

parset - set shell variables in parallel


=head1 SYNOPSIS

B<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.

The B<parset> function is defined as part of B<env_parallel>.

If I<variablename> is a single variable name, this will be treated as
the destination variable and made into an array.

If I<variablename> contains multiple names separated by ',' or space,
the names will be the destination variables.

The last bug in B<parset> was discovered 2017-06-29, so the code is
ready for being tested widely. Please use it for everyday use and
report bugs.


=head1 OPTIONS

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


=head1 SUPPORTED SHELLS

=head2 Bash

=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"

The commands to run can be an array:

  cmd=("echo '<<joe  \"double  space\"  cartoon>>'" "pwd")
  parset data ::: "${cmd[@]}"
  echo "${data[0]}"
  echo "${data[1]}"

B<parset> can not be part of a pipe. In particular this means it
cannot read anything from standard input (stdin) 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 "${res[0]}"
  echo "${res[9]}"

or a FIFO:

  mkfifo input_fifo
  seq 30 > input_fifo &
  parset res echo :::: input_fifo
  echo "${res[0]}"
  echo "${res[29]}"

or Bash process substitution:

  parset res echo :::: <(seq 100)
  echo "${res[0]}"
  echo "${res[99]}"

=head3 Installation

Put this in B<$HOME/.bashrc>:

  . `which env_parallel.bash`

E.g. by doing:

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


=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) 2010,2011,2012,2013,2014,2015,2016,2017 Ole Tange,
http://ole.tange.dk and Free Software Foundation, Inc.


=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<parset> uses GNU B<parallel>.


=head1 SEE ALSO

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


=cut