Troubleshooting Perl scripts

This guide outlines a four-step process for troubleshooting Perl scripts and resolving common issues.

Step 1: Verify file permissions

Ensure the Perl script has the correct file permissions:

• Web-accessible scripts: 755
• Command-line only scripts: 700

Incorrect permissions are a common cause of script failures.

Step 2: Verify line break settings

Check that the Perl script uses UNIX text format, not DOS format.

• UNIX and DOS formats handle line breaks differently.
• Scripts saved in DOS format may produce syntax errors.

Step 3: Run the script from the command line

Debugging via a web browser can hide error details. Running the script from SSH provides more useful information.

To run the script:

perl filename

For detailed debugging, use the Perl command-line debugger:

perl -d filename

The debugger provides line-by-line control and detailed error messages. More information is available at Perl Debugger Tutorial.

Step 4: Check web server error logs

This step applies only to CGI scripts accessed through a web browser.

• Scripts that produce 500 Internal Server Error or 403 Forbidden are logged in the web server error logs.
• Use cPanel to view your site’s error log for detailed information.

Following these steps helps identify common issues with Perl scripts and simplifies debugging.