Monitoring command outputs with watch

The watch command will execute a command at intervals and display that command's output. You can use a terminal session and the screen command described in chapter 10, Administration Calls to create a customized dashboard to monitor your systems with watch.

How to do it...

The watch command monitors the output of a command on the terminal at regular intervals. The syntax of the watch command is as follows:

$ watch COMMAND

Consider this example:

$ watch ls

Alternatively, it can be used like this:

$ watch 'df /home'

Consider the following example:

# list only directories
    $ watch 'ls -l | grep "^d"'

This command will update the output at a default interval of two seconds.

The -n SECONDS option defines the time interval for updating the output:

# Monitor the output of ls -l every of 5 seconds
    $ watch -n 5 'ls -l'

 

 

There's more

The watch command can be used with any command that generates output. Some commands change their output frequently, and the changes are...