How to use a timer in bash?

Question

I needed a timer which will start at the very beginning of the script and stops at the end.Can anyone help me with that?

Answer 1

If you want the duration in seconds, at the top use

start=$SECONDS

and at the end

duration=$(( SECONDS - start ))

Answer 2

You could use Linux's built-in time command. From the man page:

time COMMAND [arguments]

time determines which information to display about the resources used by the COMMAND from the string FORMAT. If no format is specified on the command line, but the TIME environment variable is set, its value is used as the format.

To time the cleanup.sh script, use:

$ time cleanup.sh