How to use the command 'plenv' (with examples)

The plenv command is an indispensable tool for Perl developers who need to manage multiple versions of Perl seamlessly. It allows users to easily switch between different Perl environments, ensuring that the right version is used for the right project. This flexibility is essential for developers working on numerous projects that each depend on specific Perl versions. plenv is simple to use and offers commands for checking version status, setting global or local versions, and getting help. More information can be found on its GitHub page .

Use case 1: Show the currently selected Perl version and how it was selected

Code:

plenv version

Motivation for using the example:

Understanding which Perl version is currently active is crucial when working on projects that depend on specific Perl features or modules. Knowing how the active version was determined, whether globally, locally, or via shell, helps in debugging issues related to version mismatches.

Explanation for every argument:

• version: This command shows the currently active Perl version and provides the source of this selection, which could be global, local, or shell-specific settings.

Example output:

5.32.0 (set by /home/user/.perl-version)

Use case 2: List all available installed Perl versions

Code:

plenv versions

Motivation for using the example:

Developers often need a quick overview of which Perl versions are installed on their system to decide if they need to install a new version or switch between existing ones. This command provides a comprehensive list, saving time and avoiding potential compatibility issues.

Explanation for every argument:

• versions: This command lists all the Perl versions that have been installed through plenv, indicating which ones are marked for use as global, local, or shell-specific.

Example output:

* 5.32.0 (set by /home/user/.plenv/version)
  5.34.0
  5.30.2

Use case 3: Set the global Perl version

Code:

plenv global 5.34.0

Motivation for using the example:

Setting a global Perl version is ideal for establishing a default environment for consistent use across the system. This is particularly useful when working on multiple projects that are compatible with the same Perl version and eliminating the need to repeatedly set local or shell versions.

Explanation for every argument:

• global: This argument sets the globally used Perl version across the entire system.
• 5.34.0: This specific version number is the Perl version that will be set as the default on the system.

Example output:

changed global Perl to 5.34.0

Use case 4: Set the local application-specific Perl version

Code:

plenv local 5.30.2

Motivation for using the example:

When working on a project that requires a particular Perl version, setting a local version ensures that the correct environment is used without affecting other projects. This is crucial for code compatibility and preventing project errors due to version discrepancies.

Explanation for every argument:

• local: This argument sets the Perl version for the current directory and its subdirectories, overriding the global setting.
• 5.30.2: This specific version number indicates the Perl version to be used locally in the current directory.

Example output:

changed local Perl to 5.30.2

Use case 5: Set the shell-specific Perl version

Code:

plenv shell 5.32.0

Motivation for using the example:

A shell-specific Perl version allows for instantaneous changes to the Perl environment within a terminal session. It is particularly beneficial for quick tests or when running scripts without permanently altering the global or local settings.

Explanation for every argument:

• shell: This argument sets the Perl version for the current shell session only, which means it is temporary and reverts back after the session ends.
• 5.32.0: This specific version number is the Perl version that will be used in the current shell session.

Example output:

set shell Perl to 5.32.0

Use case 6: Display help

Code:

plenv

Motivation for using the example:

New users or those unfamiliar with plenv’s commands might need guidance or a refresher. Displaying help gives an overview of the available subcommands and their functions, aiding in effectively utilizing the tool.

Explanation for every argument:

• Running plenv without arguments directly opens the help interface, listing out possible subcommands and their descriptions.

Example output:

Available subcommands:
  version
  versions
  global
  local
  shell
  ...

Use case 7: Display help for a command

Code:

plenv help global

Motivation for using the example:

Understanding the specifics of a plenv subcommand can assist in its proper utilization. This command provides detailed information about what actions the subcommand can perform, making it easier to implement correctly.

Explanation for every argument:

• help: This argument specifies that detailed help on a particular subcommand is requested.
• global: This is the subcommand for which additional information and usage instructions are sought.

Example output:

Usage: plenv global <version>
Set the global version of Perl to be used by default...

Conclusion:

The plenv command is a powerful Perl version management tool that simplifies the process of switching between Perl versions. By understanding its various use cases, developers can efficiently manage their development environments, ensuring maximum compatibility and minimal disruption. Whether you are setting versions globally, locally, or at the shell level, plenv provides the necessary commands and functionality to make Perl version management a breeze.