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#!/usr/bin/perl

# SPDX-FileCopyrightText: 2021-2023 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

=head1 NAME

parcat - cat files or fifos in parallel

=head1 SYNOPSIS

B<parcat> [--rm] [-#] file(s) [-#] file(s)

=head1 DESCRIPTION

GNU B<parcat> reads files or fifos in parallel. It writes full lines
so there will be no problem with mixed-half-lines which you risk if
you use:

   (cat file1 & cat file2 &) | ...

It is faster than doing:

   parallel -j0 --lb cat ::: file*

Arguments can be given on the command line or passed in on stdin
(standard input).

=head1 OPTIONS

=over 9

=item -B<#>

Arguments following this will be sent to the file descriptor B<#>. E.g.

  parcat -1 stdout1 stdout2 -2 stderr1 stderr2

will send I<stdout1> and I<stdout2> to stdout (standard output = file
descriptor 1), and send I<stderr1> and I<stderr2> to stderr (standard
error = file descriptor 2).

=item --rm

Remove files after opening. As soon as the files are opened, unlink
the files.

=back

=head1 EXAMPLES

=head2 Simple line buffered output

B<traceroute> will often print half a line. If run in parallel, two
instances may half-lines of their output. This can be avoided by
saving the output to a fifo and then using B<parcat> to read the two
fifos in parallel:

  mkfifo freenetproject.org.fifo tange.dk.fifo
  traceroute freenetproject.org > freenetproject.org.fifo &
  traceroute tange.dk > tange.dk.fifo &
  parcat --rm *fifo


=head1 REPORTING BUGS

GNU B<parcat> is part of GNU B<parallel>. Report bugs to
<bug-parallel@gnu.org>.


=head1 AUTHOR

Copyright (C) 2016-2023 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 9

=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

=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

GNU B<parcat> uses Perl.


=head1 SEE ALSO

B<cat>(1), B<parallel>(1)

=cut