Authoring plugins

pyenv plugins provide new commands and/or hook into existing functionality of pyenv. The following file naming scheme should be followed in a plugin project:

1. bin/pyenv-COMMAND for commands
2. etc/pyenv.d/HOOK_NAME/*.bash for hooks

pyenv commands

An pyenv command is an executable named like pyenv-COMMAND. It will get executed when a user runs pyenv COMMAND. Its help will be displayed when a user runs pyenv help COMMAND. It can be written in any interpreted language, but bash script is recommended for portability.

A plugin command can't override any of the pyenv's built-in commands.

Environment

Each pyenv command runs with the following environment:

• $PYENV_ROOT - where pyenv versions & user data is placed, typically ~/.pyenv
• $PYENV_DIR - the current directory of the caller
• $PATH - constructed to contain:
  1. pyenv's libexec dir with core commands
  2. $PYENV_ROOT/plugins/*/bin for plugin commands
  3. $PATH (external value)

Calling other commands

When calling other commands from a command, use the pyenv-COMMAND form (with dash) instead of pyenv COMMAND (with space).

Use pyenv's core low-level commands to inspect the environment instead of doing it manually. For example, read the result of pyenv-prefix instead of constructing it like $PYENV_ROOT/versions/$version.

A plugin command shouldn't have too much knowledge of pyenv's internals.

Help text

An pyenv command should provide help text in the topmost comment of its source code. The help format is described in pyenv help help.

Here is a template for an executable called pyenv-COMMAND:

#!/usr/bin/env bash
#
# Summary: One line, short description of a command
#
# Usage: pyenv COMMAND [--optional-flag] <required-argument>
#
# More thorough help text wrapped at 70 characters that spans
# multiple lines until the end of the comment block.

set -e
[ -n "$PYENV_DEBUG" ] && set -x

# Optional: Abort with usage line when called with invalid arguments
# (replace COMMAND with the name of this command)
if [ -z "$1" ]; then
  pyenv-help --usage COMMAND >&2
  exit 1
fi

Completions

A command can optionally provide tab-completions in the shell by outputting completion values when invoked with the --complete flag.

# Provide pyenv completions
if [ "$1" = "--complete" ]; then
  echo hello
  exit
fi

Note: it's important to keep the above comment intact. This is how pyenv detects if a command is capable of providing completion values.

pyenv hooks

Hooks are bash scripts named like HOOK_NAME/*.bash, where "HOOK_NAME" is one of:

• exec
• rehash
• which

Hooks are looked for in $PYENV_HOOK_PATH, which is composed of:

1. $PYENV_HOOK_PATH (external value)
2. $PYENV_ROOT/pyenv.d
3. /usr/local/etc/pyenv.d
4. /etc/pyenv.d
5. /usr/lib/pyenv/hooks
6. $PYENV_ROOT/plugins/*/etc/pyenv.d

Hook scripts are executed at specific points during pyenv operation. They provide a low-level entry point for integration with pyenv's functionality. To get a better understanding of the possibilities with hooks, read the source code of pyenv's hook-enabled commands listed above.