parcat - cat files or fifos in parallel
parcat [--rm] [-#] file(s) [-#] file(s)
GNU 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).
- Arguments following this will be sent to the file descriptor #.
parcat -1 stdout1 stdout2 -2 stderr1 stderr2
will send stdout1 and stdout2 to stdout (standard output = file descriptor 1), and send stderr1 and stderr2 to stderr (standard error = file descriptor 2).
- Remove files after opening. As soon as the files are opened, unlink the files.
Simple line buffered output¶
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 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
GNU parcat is part of GNU parallel. Report bugs to <firstname.lastname@example.org>.
Copyright (C) 2016-2021 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.
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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:
Under the following conditions:
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- 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:
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- Public Domain
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- Other Rights
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A copy of the full license is included in the file as LICENCES/CC-BY-SA-4.0.txt
GNU parcat uses Perl.