Perl is a powerful and versatile scripting language widely used for various applications, including web development, system administration, and data manipulation. As you work with Perl, it’s essential to know which modules are installed on your server to ensure compatibility, troubleshoot issues, or manage dependencies for your projects. This guide will walk you through the steps to list installed Perl modules on your server.

Why Check Installed Perl Modules?

  1. Dependency Management:
    • Knowing the installed modules helps you identify missing dependencies for your scripts or applications.
  2. Troubleshooting:
    • Helps pinpoint issues when a Perl script fails due to a missing or incompatible module.
  3. Environment Consistency:
    • Ensures that your development, staging, and production environments have consistent module versions.

Methods to List Installed Perl Modules

Here are the most common ways to list installed Perl modules:

1. Using the CPAN Shell

The Comprehensive Perl Archive Network (CPAN) is a repository of Perl modules. You can use the CPAN shell to list installed modules.

Steps:

  1. Open your terminal or SSH into your server.
  2. Run the following command:
    bash
    perl -MCPAN -e shell
  3. In the CPAN shell, type:
    bash
    m

    This will display a list of all installed modules along with their versions.

2. Using the perldoc Command

You can use the perldoc command to generate a list of installed modules.

Steps:

  1. Run this command in your terminal:
    bash
    perldoc perllocal
  2. The output will include a list of installed modules, their versions, and installation details.

3. Using the instmodsh Command

Perl provides a built-in tool called instmodsh to interactively list installed modules.

Steps:

  1. Run the command:
    bash
    instmodsh
  2. In the interactive shell, type:
    bash
    l

    This will display all installed modules.

4. Using a Script

For a programmatic approach, you can write a simple Perl script to list installed modules.

Example Script:

perl
use ExtUtils::Installed;

my $installed = ExtUtils::Installed->new();
my @modules = $installed->modules();

print "Installed Perl Modules:\n";
foreach my $module (@modules) {
    print "$module\n";
}
  • Save this script to a file, e.g., list_modules.pl.
  • Run the script:
    bash
    perl list_modules.pl

5. Using Package Managers

If Perl was installed through a package manager like apt or yum, you can use these tools to list installed modules. For example:

  • On Debian/Ubuntu:
    bash
    dpkg -l | grep perl
  • On Red Hat/CentOS:
    bash
    yum list installed | grep perl

Tips for Managing Perl Modules

  1. Update Modules Regularly:
    • Use CPAN to update modules:
      bash
      cpan upgrade
  2. Check Module Documentation:
    • Use perldoc to view module documentation:
      bash
      perldoc Module::Name
  3. Install Missing Modules:
    • Install missing modules with CPAN:
      bash
      cpan install Module::Name
  4. Use Local::Lib:
    • To avoid system-wide changes, use local::lib to manage modules in a user-specific directory.

Conclusion

Knowing how to list installed Perl modules is a vital skill for developers and administrators working with Perl. Whether you’re troubleshooting, managing dependencies, or ensuring consistency across environments, the methods outlined in this guide will help you efficiently manage your Perl modules.

If you have further questions or need assistance with Perl module management, feel free to reach out to us at iServerSupport. We’re here to simplify your server management needs!