par(1)

💖 par — bestie's guide to parallel command processing 💖

okay so you found par(1) in the General Commands Manual section and you're like "what even is this" — bestie, it's giving parallel command processing, and honestly? iconic. let's go. ✨

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🌸 SYNOPSIS 🌸

par [-FHdefiqx] [-c  command] [-l  logfile] [-n #] [-p #] [file
[file...]]

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🦋 DESCRIPTION 🦋

so par takes a list of files and runs a command on them. main character energy fr fr.

The first line of each file begins with a colon (:) or a pound-sign (#). Here's the vibe check:

• If it's a colon, the remainder of that line is a command to run for each of the subsequent lines. 💅
• If it's a pound-sign, then each subsequent line is a (self-contained) command — unless the -c option was specified, in which case the lines become the arguments replacing the braces ({}s) in the -c argument.

The input file may also be specified on stdin, in the format as previously described. no cap. 🫶

In each of the cases where the lines of the file, following the first, are not commands (ie: colon or -c), instances of open-close braces ({}) in the command will be replaced by these values. the way that works is genuinely so satisfying 😭

For example, an inputfile whose contents is:

: echo {}
a
b
c

run with par like so:

%par -q inputfile

will produce the following output (order will vary — do not come for me about the order, it's parallel, it does what it wants):

b
a
c

The command-line options are as follows:

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✨ OPTIONS ✨

• -F — Omit the footer that normally follows the output of each job. bye bye lil footer 🎀
• -H — Omit the header that normally precedes the output of each job. no intro, we're jumping straight in.
• -c — Command to be run on each of the arguments following the command-line options, where the first line of the input file(s) begins with a pound-sign (#).
• -d — Print debugging information on standard error (stderr). Repeat the option up to three times for more verbosity. (so -ddd is max yap mode, and honestly, we love a yapper)
• -e — Split args by spaces, rather than using sh -c. > Note: -e is incompatible with the -i option. pick a lane bestie 💀
• -f — No input file or STDIN, just run a quantity of the command specified with -c.
• -i — Run commands interactively through (multiple) xterm(1) processes. windows everywhere, very demure, very mindful 🪟
• -l — Prefix of logfile name, as in prefix.N where N is the par process number ([0..]).

Default: par.log.<time>.[0..]

• -n N — Number of simultaneous processes.

Default: 3

• -p N — Pause N seconds between running commands. a lil breather 😮‍💨
• -q — Quiet mode. Omit the typical processing logs and do not create the log files from -l, instead the children inherit stdout and stderr from par. -q is mutually exclusive with the -x and -l options and the option appearing last will take precedence. so whoever shows up last wins, periodt 👑
• -x — View par logs in real-time via an xterm(1). live reaction cam 🔥

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💜 FILES 💜

• par.log.T.N — Log file; where T is the current time in seconds since the epoch and N is the par process number ([0..]).

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🌈 HISTORY 🌈

par was ported from the perl version. It differs in the following manner:

1. If par receives a HUP/INT/TERM/QUIT signal, it does not print the commands that will not be run.
2. If par received a HUP/INT/TERM/QUIT signal, it does not exit immediately after sending kill to running jobs. it waits for them to exit so that they are cleaned-up properly. If a second signal is received, it dies immediately. 😭 she said "not twice, bestie."

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and that's the whole page, bestie!! this edition of the manual was served up on 29 July 2019, and it's par(1) from the General Commands Manual — so if anyone asks where you learned all this, you can say the source material was dated and you still ate. 💅✨ stay parallel, stay slay. 🫶