ve.sh

#!/bin/sh
#
# Copyright (c) 2016 Ming Qin (覃明) <https://github.com/QinMing>
# Open source under MIT LICENSE.
# You are more than welcome to come together and make this better.

ve() {

  # Change path here, or add it as environment variable
  if [ ! -n "$VENV_ROOT" ]; then
    local VENV_ROOT=$HOME/virtualenvs
  fi
  local HISTORY_FILE=$VENV_ROOT/.history

  if [ ! -f "$HISTORY_FILE" ]; then  # exists and is a regular file
    if [ ! -d "$VENV_ROOT" ]; then  # exists and is a directory
      mkdir -p $VENV_ROOT
      echo "Created folder $VENV_ROOT for storing venvs."
    fi
    touch $HISTORY_FILE
  fi

  case "$1" in

    "")
      local key=$PWD
      while
        # -o only the matching part
        # -e pattern
        local right_part=`grep "$key:::" $HISTORY_FILE | grep -o -e ":::.*$"`

        if [ -n "$right_part" ]; then # if non-empty string
          # Truncate the first three ':', then activate virtualenv
          ve ${right_part:3}
          return
        fi

        local key=`dirname $key`
        [ "$key" != "/" ]
      do :; done
      ve -h
      return
      ;;

    -[lL]|--list)
      # echo `find $VENV_ROOT/* -maxdepth 0 -type d | xargs basename`
      # ls -d -1 $VENV_ROOT/* | xargs basename
      # echo ${PWD##*/}

      # The -F'/' sets the field separator to / which means that the last field, $NF, will be the file name.
      ls -1 $VENV_ROOT | awk -F'/' '{print $NF}'
      return
      ;;

    -[dD]|--delete)

      if [ -z "$2" ]; then
        echo 'Not enough argument'
        ve -h
        return
      fi

      if [ -n "$ZSH_VERSION" ]; then
        read "REPLY?rm -rf $VENV_ROOT/$2 : Is this OK? (y/n)"
      else
        if [ -z "$BASH_VERSION" ]; then
          echo "Warning: probably unsupported shell. Assume using bash"
        fi
        read -p "rm -rf $VENV_ROOT/$2 : Is this OK? (y/n)" -n 1 -r
      fi

      echo
      if [[ "$REPLY" =~ ^[Yy]$ ]]
      then
        rm -rf $VENV_ROOT/$2
      fi
      return
      ;;

    -[rR]|--root)
      echo "not implemented yet"
      return
      ;;

    -[eE]|--exit)
      deactivate
      return
      ;;

    --history)
      vim $HISTORY_FILE
      return
      ;;

    -*)
      echo "Simple virtualenv wrapper for Python"
      echo
      echo "Usage:"
      echo "  ve [option] <name> [additional options]"
      echo
      echo "Options:"
      echo "  without option       Activate virtualenv, or create one if doesn't exist."
      echo "                       Only when creating new environments, you can add"
      echo "                       options that will be passed to virtualenv."
      echo "                       See \`virtualenv -h\`"
      echo "  -d, --delete <name>  Delete a virtualenv."
      echo "  -e, --exit           Deactivate."
      echo "  -h, --help           Show this info."
      echo "  -l, --list           List existing virtualenvs (things in VENV_ROOT)."
      echo "  --history            Edit (vim) the history file. "
      echo "  -r, --root           Change the root path."
      return
      ;;

    *)
      local venv_name=$1
      local venv_path=$VENV_ROOT/$1
      local actv=$venv_path/bin/activate

      if [ ! -s "$actv" ]; then  # virtualenv doesn't exist, let's create one
        shift 1
        if [ -n "$ZSH_VERSION" ]; then
          read "REPLY?virtualenv $venv_path $* : Is this OK? (y/n)"
        else
          if [ -z "$BASH_VERSION" ]; then
            echo "Warning: probably unsupported shell. Assume using bash"
          fi
          read -p "virtualenv $venv_path $* : Is this OK? (y/n)" -n 1 -r
        fi
        echo
        if [[ "$REPLY" =~ ^[Yy]$ ]]
        then
          virtualenv $venv_path $*
        fi
      fi

      if [ -s "$actv" ]; then  # check the `activate` file again
        source $actv

        local key=$PWD
        local right_part=`grep "$key:::" $HISTORY_FILE | grep -o -e ":::.*$"`
        if [ -n "$right_part" ]; then  # if non-empty, meaning there is entry in history
          if [ "$right_part" != ":::$venv_name" ]; then  # if diff string
            # Change the value under `key` in history file
            echo "Changing venv for \"$key\": { ${right_part:3} => $venv_name }."
            printf "%s\n" `grep -v "$key:::" $HISTORY_FILE` > $HISTORY_FILE  # remove line
            echo "$key:::$venv_name" >> $HISTORY_FILE
          else
            # Do nothing
            echo "\"$venv_name\" is now activated."
          fi
          return
        fi

        # Create new entry in history file
        echo "$PWD:::$venv_name" >> $HISTORY_FILE
        echo "Next time, you can just type \`ve\` in this folder, or sub-folders, to activate $venv_name"
      fi
      return
      ;;
  esac
}