run-one(1)

💖 run-one(1) — the "bestie, you only need ONE of these running" manual 💖

okay so hi, this is run-one from the run-one family of scripts and honestly? it's giving cronjob guardian angel. let's get into it. ✨

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🌸 NAME 🌸

run-one — run just one instance at a time of some command and unique set of arguments (useful for cronjobs, eg)

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🎀 SYNOPSIS 🎀

run-one COMMAND [ARGS]

run-this-one COMMAND [ARGS]

run-one-constantly COMMAND [ARGS]

keep-one-running COMMAND [ARGS]

run-one-until-success COMMAND [ARGS]

run-one-until-failure COMMAND [ARGS]

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🦋 DESCRIPTION 🦋

run-one is a wrapper script that runs no more than one unique instance of some command with a unique set of arguments.

This is often useful with cronjobs, when you want no more than one copy running at a time.

run-this-one is exactly like run-one, except that it will use pgrep(1) and kill(1) to find and kill any running processes owned by the user and matching the target commands and arguments. Note that run-this-one will block while trying to kill matching processes, until all matching processes are dead. 😭

run-one-constantly operates exactly like run-one except that it respawns "COMMAND [ARGS]" any time COMMAND exits (zero or non-zero). it's giving "we go again" energy 🔥

keep-one-running is an alias for run-one-constantly. same girl, different name 💅

run-one-until-success operates exactly like run-one-constantly except that it respawns "COMMAND [ARGS]" until COMMAND exits successfully (ie, exits zero). 🎉

run-one-until-failure operates exactly like run-one-constantly except that it respawns "COMMAND [ARGS]" until COMMAND exits with failure (ie, exits non-zero). 💀

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🌈 EXAMPLE 🌈

In one shell:

$ run-one rsync -azP $HOME $USER@example.com:/srv/backup
foouser/
foouser/.bash_history
      40298 100%   37.13MB/s    0:00:00 (xfer#1, to-check=3509/3516)
foouser/.viminfo
      20352 100%   98.39kB/s    0:00:00 (xfer#3, to-check=3478/3516)
...
sent 746228 bytes  received 413059 bytes  36802.76 bytes/sec
total size is 3732890955  speedup is 3219.99

In another shell, while the first is still running:

$ run-one rsync -azP $HOME $USER@example.com:/srv/backup
$ echo $?
1

Another example... In one shell:

$ run-one top

In another shell:

$ run-one top
$ echo $?
1
$ run-this-one top
top - 17:15:36 up  1:43,  3 users,  load average: 1.05, 1.04, 1.00
Tasks: 170 total,   1 running, 169 sleeping,   0 stopped,   0 zombie
...

And note that the process in the first shell was killed. 🫢

You might want to keep one ssh connection up and running all the time, with:

$ run-one-constantly ssh -N -C -L 3128:localhost:3128 -L 7778:localhost:7778 example.com &

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💜 SEE ALSO 💜

flock(1), kill(1), pgrep(1)

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👑 AUTHOR 👑

This manpage and the utility was written by Dustin Kirkland <kirkland@ubuntu.com> for Ubuntu systems (but may be used by others). Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License, Version 3 published by the Free Software Foundation.

On Debian systems, the complete text of the GNU General Public License can be found in /usr/share/common-licenses/GPL, or on the web at http://www.gnu.org/licenses/gpl.txt.

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and that's the whole thing, bestie 🫶 this was run-one, from the run-one manual, and it's dated 9 Jan 2011 — iconic, timeless, lowkey ancient but still serving. go forth and cron responsibly. 💖✨