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

Plenv is a command-line tool that allows users to switch between multiple versions of Perl. It provides a convenient way to manage different Perl versions for different applications or projects. This article will illustrate the various use cases of the ‘plenv’ command and provide examples for each use case.

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

Code:

plenv version

Motivation: This use case allows the user to check which Perl version is currently selected and how it was selected. It is useful when troubleshooting Perl version-related issues or when verifying if a specific Perl version is being used.

Explanation: The ‘plenv version’ command displays the currently selected Perl version and the method used to select it. The method can be one of three options: global, local, or shell. The global version is used unless a local or shell version takes priority.

Example output:

system (set by /home/user/.plenv/version)

Use case 2: List all available installed Perl versions

Code:

plenv versions

Motivation: This use case allows the user to view a list of all the Perl versions that are currently installed on their system. It is useful when deciding which Perl version to use for a specific project or when checking the available Perl versions for compatibility purposes.

Explanation: The ‘plenv versions’ command lists all the Perl versions that are installed and available for use. It displays both the installed versions and the associated paths. The currently selected version will be marked with an asterisk (*).

Example output:

* 5.30.1 (set by /home/user/.plenv/version)
  5.28.2
  5.26.3

Use case 3: Set the global Perl version

Code:

plenv global version

Motivation: This use case allows the user to set the global Perl version, which is used unless a local or shell version takes priority. It is useful when wanting to switch the default Perl version for the entire system or when installing a new Perl version and wanting it to be the default.

Explanation: The ‘plenv global’ command is used to set the global Perl version. The ‘version’ argument should be the desired Perl version to set. It can be specified either as the version number or as a path to the Perl executable.

Example:

plenv global 5.28.2

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

Code:

plenv local version

Motivation: This use case allows the user to set a local application-specific Perl version. The local version will be used in the current directory and all directories below it. It is useful when working on multiple projects with different Perl requirements or when wanting to isolate the Perl version for a specific project.

Explanation: The ‘plenv local’ command is used to set the local application-specific Perl version. The ‘version’ argument specifies the Perl version to use. It can be specified either as the version number or as a path to the Perl executable.

Example:

plenv local 5.26.3

Use case 5: Set the shell-specific Perl version

Code:

plenv shell version

Motivation: This use case allows the user to set a shell-specific Perl version, which will be used for the current session only. It is useful when needing to temporarily switch Perl versions for a specific shell session without affecting the global or local versions.

Explanation: The ‘plenv shell’ command is used to set the shell-specific Perl version. The ‘version’ argument specifies the Perl version to use. It can be specified either as the version number or as a path to the Perl executable.

Example:

plenv shell 5.30.1

Use case 6: Display help

Code:

plenv

Motivation: This use case allows the user to display general help information about the ‘plenv’ command. It is useful when needing a quick reference on how to use the command or when wanting to explore the available options and commands.

Explanation: Running the ‘plenv’ command without any arguments displays general help information. It provides an overview of ‘plenv’ and lists the available commands. It also includes a brief explanation of each command and their usage.

Example output:

usage: plenv [--version | --help]
       plenv <command> [--help]

Some useful plenv commands are:
   versions              list installed Perl versions
   global <version>      set or show the global Perl version
   local <version>       set or show the local application-specific Perl version
   shell <version>       set or show the shell-specific Perl version
   version               show the current Perl version
   help <command>        show help for a command

Use case 7: Display help for a command

Code:

plenv help command

Motivation: This use case allows the user to get help specifically for a particular command. It is useful when needing more detailed information about the usage, options, or arguments of a specific ‘plenv’ command.

Explanation: The ‘plenv help’ command is used to display help information for a specific command. The ‘command’ argument should be the name of the command you want help for. It provides a detailed explanation of the command, including its usage, available options, and any additional arguments.

Example:

plenv help versions

Example output:

Usage: plenv versions [--bare]
Lists all versions of Perl (both installed and uninstalled) known to plenv.

  - bare: just the versions delimited by whitespaces

Conclusion:

The ‘plenv’ command provides a convenient way to manage different versions of Perl. From checking the currently selected version to setting global, local, and shell-specific versions, ‘plenv’ allows users to easily switch between Perl versions based on their specific needs. The ability to list available versions and display detailed help information makes it even more powerful and user-friendly. Whether you need to work on multiple projects with different Perl requirements or simply want to switch to a newer Perl version, ‘plenv’ has got you covered.