Create virtualenv-auto-activate.sh

I don't remember where I got this script or I would provide credit. Useful if you use virtualenv.

virtualenv-auto-activate.sh

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+#!/bin/bash
+# virtualenv-auto-activate.sh
+# 
+# Installation:
+#   Add this line to your .bashrc or .bash-profile:
+#
+#       source /path/to/virtualenv-auto-activate.sh
+#
+#   Go to your project folder, run "virtualenv .venv", so your project folder
+#   has a .venv folder at the top level, next to your version control directory.
+#   For example:
+#   .
+#   ├── .git
+#   │   ├── HEAD
+#   │   ├── config
+#   │   ├── description
+#   │   ├── hooks
+#   │   ├── info
+#   │   ├── objects
+#   │   └── refs
+#   └── .venv
+#       ├── bin
+#       ├── include
+#       └── lib
+#
+#   The virtualenv will be activated automatically when you enter the directory.
+_virtualenv_auto_activate() {
+    if [ -e ".venv" ]; then
+        # Check to see if already activated to avoid redundant activating
+        if [ "$VIRTUAL_ENV" != "$(pwd -P)/.venv" ]; then
+            _VENV_NAME=$(basename `pwd`)
+            echo Activating virtualenv \"$_VENV_NAME\"...
+            VIRTUAL_ENV_DISABLE_PROMPT=1
+            source .venv/bin/activate
+            _OLD_VIRTUAL_PS1="$PS1"
+            PS1="($_VENV_NAME)$PS1"
+            export PS1
+        fi
+    fi
+}
+
+export PROMPT_COMMAND=_virtualenv_auto_activate
+