Autodetect "source" for activating virtualenv commands in bash

Author: mdmintz

virtualenv_install.sh

@@ -4,25 +4,36 @@
 #
 # Run by using the following command: "source virtualenv_install.sh"
 
-python -m pip install --upgrade virtualenv
-python -m pip install --upgrade virtualenvwrapper
-source `which virtualenvwrapper.sh`
-export WORKON_HOME=$HOME/.virtualenvs
-echo ""
-echo ""
-echo 'virtualenv commands will only work if you installed this using "source":'
-echo '    ***  "source virtualenv_install.sh"  ***'
-echo ""
-echo ""
-echo "*** You may now use virtualenv commands in your command shell. ***"
-echo ""
-echo "virtualenv commands:"
-echo '  *  "mkvirtualenv [ENV_NAME]"  -  Create a Python virtual environment'
-echo '  *  "deactivate"               -  Exit the current virtual environment'
-echo '  *  "workon [ENV_NAME]"        -  Enter an existing virtual environment'
-echo '  *  "lsvirtualenv" OR "workon" -  List all virtual environments'
-echo '  *  "rmvirtualenv [ENV_NAME]"  -  Delete a virtual environment'
-echo ""
-echo "Example:"
-echo "      mkvirtualenv seleniumbase "
-echo ""
+[[ $0 != "$BASH_SOURCE" ]] && sourced=1 || sourced=0
+if [ $sourced = 1 ]
+then
+  python -m pip install --upgrade virtualenv
+  python -m pip install --upgrade virtualenvwrapper
+  source `which virtualenvwrapper.sh`
+  export WORKON_HOME=$HOME/.virtualenvs
+  echo ""
+  echo ""
+  echo "*** You may now use virtualenv commands in your command shell. ***"
+  echo ""
+  echo "virtualenv commands:"
+  echo '  *  "mkvirtualenv [ENV_NAME]"  -  Create a Python virtual environment'
+  echo '  *  "deactivate"               -  Exit the current virtual environment'
+  echo '  *  "workon [ENV_NAME]"        -  Enter an existing virtual environment'
+  echo '  *  "lsvirtualenv" OR "workon" -  List all virtual environments'
+  echo '  *  "rmvirtualenv [ENV_NAME]"  -  Delete a virtual environment'
+  echo ""
+  echo "Example:"
+  echo "      mkvirtualenv seleniumbase "
+  echo ""
+else
+  echo ""
+  echo "--------------------"
+  echo '*** - WARNING! - ***'
+  echo "--------------------"
+  echo ""
+  echo 'You need to "source" this file for virtualenv commands to work!'
+  echo ""
+  echo '*** USE:  source virtualenv_install.sh'
+  echo "          ----------------------------"
+  echo ""
+fi