1 minute, 46 seconds

A quick post to spread the love about the watch command – it’s amazing!

Prior to your knowledge of watch, maybe you wanted to run a command every 2 seconds, like say hello (credit to SO for this one):

$ while true
> do
>    echo "hello"
>    sleep 2
> done

But this is tedious and awkward. Maybe you collapse into the ol’ bash oneliner:

while true; do echo "hello";sleep 2;done

This is a small improvement, but A better way is with watch!

watch echo "hello"

So much nicer, right?! Watch runs any command you follow it with ever 2 seconds – boom!

But the real power comes when your checking the progress of something over time. Maybe you want to see when the login for a website comes backup with a 200 ? You’d of course reach for curl, but it’s a pain to run over and over. Again, watch makes short work of this:

watch 'curl -o /dev/null -s -w "%{http_code}\n"  https://example.com/login'

But the real REAL REAL power, in my opinion, is when you want to do multiple things at a time. So instead of switching back and forth between terminals to do so, just chain them together with a bit of echo for spacing. This makes it trivial to watch the load average, get the last few lines of a debug log and tail a docker container all in one spot like so:

DOCKER LOGS";docker logs some-container --since 10s;echo;echo "DEBUG CSV";tail --lines 2 debug.csv;echo;echo "UPTIME";uptime

This looks like this:

Every 2.0s: echo "DOCKER L...  ip-172-31-27-227: Wed Oct 8 23:04:22 2025

DOCKER LOGS
2025-10-08T22:30:30.673 INFO: foo/bar                        [100%]
2025-10-08T22:30:30.673 INFO: foo/quux-client                [54%]
2025-10-08T22:30:35.676 INFO: foo/foo                        [100%]
2025-10-08T22:30:35.676 INFO: foo/quux-client                [55%]

DEBUG CSV
1759962312,4.21.1,3.5.0,89844560,108220976
1759962433,4.21.1,3.5.0,92531624,108619512

UPTIME
 22:30:36 up 15 days, 35 min,  3 users,  load average: 14.13, 13.83, 16.16

The beauty of this Is that I started quickly with just one command running in watch. Then I could iteratively add another one and anothe rone. The longer the job ran, the more I could add in, like the nice labels in echo and such. I’m SSHed in to a remote server and I’m tmux`ed up to my neck and in one of the panes, this watch job dutifully runs, keeping “watch” on all things (see what I did there?).

The fact that watch handles the refresh (configurable too!) and redraws the content in place without any flickering is just lovely! watch on!!