What are common pitfalls or gotchas with shebangs and portability?

When using shebangs (#!) in Perl scripts, there are several common pitfalls and gotchas that can affect portability across different environments. Here’s an overview of some of these issues:

  • Path to Perl Interpreter: The shebang line may specify the path to the Perl interpreter differently on various systems. For example, some systems may have Perl located at /usr/bin/perl, while others might have it at /usr/local/bin/perl. Using /usr/bin/env can help mitigate this issue.
  • Line Endings: Windows uses CRLF (Carriage Return + Line Feed) line endings, while Unix/Linux uses LF (Line Feed). This can lead to problems when transferring scripts between systems or running them in different environments.
  • File Permissions: Ensure that your script has the appropriate executable permissions set. Without these, even with the correct shebang line, the script won’t execute as expected.
  • Environment Variables: Different environments may have different settings for environment variables needed by your scripts. Make sure to account for this if your script behaves differently in different contexts.
  • Whitespace Sensitivity: Be cautious about leading whitespace in your shebang line, as it can prevent the script from executing properly.

By being aware of these pitfalls, you can increase the portability of your Perl scripts across different systems.

Here’s an example of a shebang line that increases portability:

#!/usr/bin/env perl

Perl shebang portability scripting line endings file permissions environment variables