The Chronic: run a command every N seconds in the background

chronic () { t=$1; shift; while true; do $@; sleep $t; done & }
Chronic Bash function: chronic 3600 time # Print the time in your shell every hour chronic 60 updatedb > /dev/null # update slocate every minute Note: use 'jobs' to list background tasks and fg/bg to take control of them.

By: rhythmx
2009-06-13 05:57:54

What Others Think

Crontab/at commands would be better, if you have the rights to use them.
jxy · 644 weeks and 4 days ago
I use while true to make neverending loops with while.
b2e · 644 weeks and 4 days ago
In case you want it as a foreground process, this is exactly what 'watch' is for. watch repeatedly executes a command at a user-specified interval and displays the results. I agree with the others, if you make it a background process, you might as well automate it with cron.
bwoodacre · 644 weeks and 4 days ago
Doh.. totally forgot about `watch'. Anyway running things in a term as opposed to cron can have distinct advantages. The command will only ever run as long as your session, and you'll get all of your environment vars automatically (e.g. DISPLAY). I just pasted that from my new shiny .xinitrc for fluxbox, it watches for mtime updates to my wallpaper JPEG and automatically updates the rootbg when it changes.
rhythmx · 644 weeks and 4 days ago
Could use incron for that purpose rhythmx.
DaveQB · 644 weeks and 2 days ago
you can avoid while true: chronic () { t=$1; shift; while sleep $t; do $@; done & }
glaudiston · 585 weeks and 2 days ago
or better, if you want it, do not need to do a function, use while directly: while sleep ; do ; done &
glaudiston · 585 weeks and 1 day ago
the command above was modified by site: while sleep <you time>; do <your command>; done;
glaudiston · 585 weeks and 1 day ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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