Run Command Every X Second

Run Command Every X Second

A system administrator often needs to run a command repeatedly in a certain periods of time. Often such tasks can be easily completed with s... 21.30

A system administrator often needs to run a command repeatedly in a certain periods of time. Often such tasks can be easily completed with simple cron commands. In most of the cases  this should work, but the shortest period which you can run cron command is every 1 minute. Believe it or not, in many cases this is too slow.

Run Linux Command Every Second

In this tutorial, you will learn a simple scripting techniques to monitor or keep a eye on a particular command in continuously running state similar to top command (continuously monitor the process and memory utilization)for every 3 seconds by default.

We will not stop to discuss the reasons, why you would need to run commands this often. I believe everyone has different reasons for that in their daily jobs or even at home PCs and laptops.

1. Use watch Command

Watch is a Linux command that allows you to execute a command or program periodically and also shows you output on the screen. This means that you will be able to see the program output in time. By default watch re-runs the command/program every 2 seconds. The interval can be easily changed to meet your requirements.

Monitor Memory Usage

“Watch” is extremely easy to use, to test it, you can fire up a Linux terminal right away and type the following command:

# watch free -m

The above command will check your system free memory and update the results of the free command every two seconds.