pyenv/libexec/pyenv-local

#!/usr/bin/env bash
#
# Summary: Set or show the local application-specific Python version
#
# Usage: pyenv local <version>
#        pyenv local --unset
#
# Sets the local application-specific Python version by writing the
# version name to a file named `.python-version'.
#
# When you run a Python command, pyenv will look for a `.python-version'
# file in the current directory and each parent directory. If no such
# file is found in the tree, pyenv will use the global Python version
# specified with `pyenv global'. A version specified with the
# `PYENV_VERSION' environment variable takes precedence over local
# and global versions.
#
# <version> should be a string matching a Python version known to pyenv.
# The special version string `system' will use your default system Python.
# Run `pyenv versions' for a list of available Python versions.

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

# Provide pyenv completions
if [ "$1" = "--complete" ]; then
  echo --unset
  echo system
  exec pyenv-versions --bare
fi

versions=("$@")

if [ "$versions" = "--unset" ]; then
  rm -f .python-version .pyenv-version
elif [ -n "$versions" ]; then
  previous_file="$(PYENV_VERSION= pyenv-version-origin || true)"
  pyenv-version-file-write .python-version "${versions[@]}"
  if [ "$previous_file" -ef .pyenv-version ]; then
    rm -f .pyenv-version
    { echo "pyenv: removed existing \`.pyenv-version' file and migrated"
      echo "       local version specification to \`.python-version' file"
    } >&2
  fi
else
  OLDIFS="$IFS"
  IFS=: versions=($(
    pyenv-version-file-read .python-version ||
    pyenv-version-file-read .pyenv-version ||
    { echo "pyenv: no local version configured for this directory"
      exit 1
    } >&2
  ))
  IFS="$OLDIFS"
  for version in "${versions[@]}"; do
    echo "$version"
  done
fi