Notice that when you used perl -e ‘...whatever...’, you actually were executing a Perl script, consisting of that one string.

Most commonly, you build a command-file, written in Perl, that contains what you want to do.

There are two reasonable ways to do this.   One is to create a file with the extension .pl and execute it with:   perl whatever.pl.

Another way is, to make a command-file that can be run as an ordinary console command.   You’ll start the file with a “shebang” on the first line, e.g. #!/usr/bin/perl. On a Unix-like system, you use chmod to make the file “executable.”   Now, you can simply run the file, as you would any other command.   The shell will look at the “shebang” line and understand that it is meant for Perl.

(After so many years, Microsoft is beginning to offer a quasi-decent shell with their systems, which they have rather-amusingly dubbed PowerShell.™   My impression is that it vaguely similar in this regard...)