Hi,

Well, Ill tell you, I have been programming in Perl for many a year now and, every once in a while, an ISE will nail me for some time too! Here is my checklist:

• Check the #! line of your script against the path to perl. Never assume that because you can run it from the comand line (./script.pl) that it will work in CGI. Your ENV will be different from Apache's (i.e. PATHs). The line should be something like #!/usr/bin/perl or #!/usr/local/bin/perl and never #!perl
• Make sure your script's permissions are set correctly for your configuration. This changes from one setup to the next, but is often something like: RWX R-X R-X. In some configs, it is important to have execute perms on the file.
• IMPORTANT: make sure the script's parent directory does not offer group or others write access (eg. the perms should be RWX R-X R-X). Many mod_cgi configs will not let you execute a script if it is in a dir that offers group or others write access.
• Check your error log. I assume you already have.
• Are you sure you script is generating output. Try putting the following line at the top of your script. If it generates a blank page, then you know your script is being executed and is just not generating content:

BEGIN{ print "Content-type: text/html\n\n" }
[download]

On this note, your script may be generating output, just note the proper headers. The headers won't be automatically sent, you have to print them yourself.

This can be a pain sometimes. If I think of anything else, Ill update this note. Good luck!

update: Some spelling errors.

That's a good check list.

I would add two points:

Check the line endings (may not be appropriate in this case).
Check that the script you are testing _is really_ the one you think it is!

The last one caused me a lot of grief!