Home > python > using virtualenv (Part 2)

using virtualenv (Part 2)

In Part 1 we saw how to use virtualenv.

Now let’s see how to colorize the bash prompt and how to activate a virtual environment easily.

Colorize the prompt
When a virtual env. is activated, the prompt changes. However, this change is not very visible because it’s not colorized. The name of the virtual env. should be printed with a different color, thus it would be visible immediately if an env. is activated or not.

Fortunately someone else also had this problem :) Here I found an excellent solution. I only changed the PS1 line the following way:

  PS1="${PYTHON_VIRTUALENV}${GREEN}\u@\h ${YELLOW}\w${COLOR_NONE} ${BRANCH}${PROMPT_SYMBOL} "

This way the prompt and the cursor are in one line. I made a fork, my slightly modified version is available here.

Update (20131001): I updated the script above to support light background too. Instructions are in the header in a comment.

Usage

Save the file above as ~/.bash_prompt and add the following line to the end of your ~/.bashrc:

source ~/.bash_prompt

The resulting prompt is way cooler than the default bash prompt, thus you can use it even if you don’t work with virtual environments!

See the end of the post for a screenshot.

Activating a virtual environment easily
The standard way for activating a virtual env. is to source the script “activate“:

jabba@jabba-uplink ~/python/mystuff $ ls -al
total 24
drwxrwxr-x   3 jabba jabba  4096 Sep 21 16:16 .
drwxrwxr-x 234 jabba jabba 12288 Sep 21 15:58 ..
-rwxrw-r--   1 jabba jabba    53 Sep 21 16:16 hello.py
drwxrwxr-x   6 jabba jabba  4096 Sep 21 16:13 venv
jabba@jabba-uplink ~/python/mystuff $ . venv/bin/activate
[venv] jabba@jabba-uplink ~/python/mystuff $

However, using the command “workon venv” would be much easier. I wanted to do it with an alias, but bash aliases do not accept arguments. There is a workaround: use functions instead.

Add the following lines to your ~/.bashrc:

func_workon()
{
if [[ -z "$1" ]]
then
    echo "Usage: workon <venv>"
else
    . $1/bin/activate
fi
}
alias workon=func_workon

alias workoff='deactivate'

Now you can activate a virtual env. much easier:

jabba@jabba-uplink ~/python/mystuff $ ls -al
total 24
drwxrwxr-x   3 jabba jabba  4096 Sep 21 16:16 .
drwxrwxr-x 234 jabba jabba 12288 Sep 21 15:58 ..
-rwxrw-r--   1 jabba jabba    53 Sep 21 16:16 hello.py
drwxrwxr-x   6 jabba jabba  4096 Sep 21 16:13 venv
jabba@jabba-uplink ~/python/mystuff $ workon venv
[venv] jabba@jabba-uplink ~/python/mystuff $

For deactivation use the command “deactivate“, or my alias “workoff“.

Screenshot
workon

Next step
There is virtualenvwrapper, which is “a set of extensions to Ian Bicking’s virtualenv tool. The extensions include wrappers for creating and deleting virtual environments and otherwise managing your development workflow, making it easier to work on more than one project at a time without introducing conflicts in their dependencies.

I haven’t used it yet.

About these ads
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 72 other followers

%d bloggers like this: