You could run it from the command line as you say, or from a script.

You can program "in the terminal" exactly as you would in a script.

If your shell is /bin/ksh, for example (echo $0 to see what shell you are running), you can type ksh commands on the command line exactly as you would write them in a script.

So whether you run

from the command line, or put it into a file and execute the file, the result is the same.

If you're very new to this you might want to avoid Perl just for now!