How to execute a linux command repeatedly after a set time

Question

Is it possible in linux command line to have a command repeat every n seconds.

I want to execute  a command after say every 2 minutes. Say for example I have an import statement running and I'm doing:

ls -l

to check the file size is increasing. Is there someway I can do this automatically.

Answer 1

To watch the step every say 30 seconds do:

watch -n 30 ls -l

In case you want this to print the differences add --differences flag before the ls command.

According to the OSX man page, there's also

The --cumulative option makes highlighting "sticky", presenting a running display of all positions that have ever changed. The -t or --no-title option turns off the header showing the interval, command, and current time at the top of the display, as well as the following blank line.

Linux/Unix man page can be found here