Running the program

Type in the example program using a text editor, and save it. Emacs is a good editor to use for this because it has its own Perl mode which formats lines nicely when you hit tab (use `M-x perl-mode'). But as ever, use whichever you're most comfortable with.

After you've entered and saved the program make sure the file is executable by using the command

chmod u+x progname
at the UNIX prompt, where progname is the filename of the program. Now to run the program just type any of the following at the prompt.
perl progname

If something goes wrong then you may get error messages, or you may get nothing. You can always run the program with warnings using the command

perl -w progname
at the prompt. This will display warnings and other (hopefully) helpful messages before it tries to execute the program. To run the program with a debugger use the command
perl -d progname

When the file is executed Perl first compiles it and then executes that compiled version. So after a short pause for compilation the program should run quite quickly. This also explains why you can get compilation errors when you execute a Perl file which consists only of text.

Make sure your program works before proceeding. The program's output may be slightly unexpected - at least it isn't very pretty. We'll look next at variables and then tie this in with prettier printing.

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