I’ve been running a lot of scripts recently that require me to check on things that I can’t monitor with `tail -f logname`. Mainly to keep an eye on a process and get information about the processes running that I’m interested in. Periodically, one hangs and I like to just jump back to it and kill it.

Watch to the rescue!

Watch executes a command at a specified period. For instance, if I’m extracting a file and want to monitor the progress, I can simply type:

watch 'ls -la filename.ext'

and I will get the output from `ls -la filename.ext` every 2 seconds.

If my internet connection is down and I am impatiently waiting for it to come back up, I can run:

watch -n15 'ping -c1 www.google.com'

If I’m forking processes in a Bash script and want to make sure none of them are hung:

watch -n2 'ps ax|grep [p]rocessname'

It’s very handy!

I periodically come across an issue whereby `tail -f /var/log/syslog` will hang after operating for a couple of hours. I solve this by using the following instead:

watch -n5 'tail -n20 /var/log/syslog'

`man watch` to find more uses for this program. I tried `woman watch` but apparently Linux doesn’t carry those.

and holy sweet crap, it’s been a long time since I wrote an article on this site!

Until next time,

-LightningCrash

This entry was posted on Tuesday, January 8th, 2008 at 3:24 pm and is filed under watch. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.