watch Command Examples in Linux

If you need to keep an eye on a command whose output is changing, use the watch command. For example, to keep an eye on your load average:

$ watch 'cat /proc/loadavg'

Every two seconds, watch runs the cat command again. Use Ctrl+c to quit. To change the refresh rate to 10 seconds, type the following:

$ watch -n 10 'ls -l'

To highlight the difference between screen updates, type:

$ watch -d 'ls -l'

Type Ctrl+c to exit the watch command.

You can use the watch command to watch the size of a file. For example, to watch a large ISO file named mydownload.iso as it downloads, use the following command:

$ watch 'ls -l mydownload.iso'

watch Command Examples

1. Repeatedly run a command and show the result:

# watch command

2. Re-run a command every 60 seconds:

# watch -n 60 command

3. Monitor the contents of a directory, highlighting differences as they appear:

# watch -d ls -l

4. Repeatedly run a pipeline and show the result:

# watch 'command_1 | command_2 | command_3'