"python" still runs the system version after virtualenv activate

Bottom line:

You have set "python" as a shell alias (probably in your shell startup scripts). It interferes with virtualenv's work of replacing what would be run when you type "python". Remove the alias, and you're good.

You also don't need to specify --python=/usr/local/bin/python2.7 'cuz you're using virtualenv from that Python installation, so it already uses it by default.

WFM with virtualenv 1.10.1: (see a guess further below)

$ virtualenv --python=/usr/local/bin/python2.7 testbox
Running virtualenv with interpreter /usr/local/bin/python2.7
New python executable in testbox/bin/python2.7
Also creating executable in testbox/bin/python
Installing Setuptools.........................................done.
Installing Pip................................................done.
$ ls -l testbox/bin/
total 40
-rw-r--r--. 1 root root 2194 Dec  7 03:06 activate
-rw-r--r--. 1 root root 1250 Dec  7 03:06 activate.csh
-rw-r--r--. 1 root root 2389 Dec  7 03:06 activate.fish
-rw-r--r--. 1 root root 1129 Dec  7 03:06 activate_this.py
-rwxr-xr-x. 1 root root  332 Dec  7 03:06 easy_install
-rwxr-xr-x. 1 root root  340 Dec  7 03:06 easy_install-2.7
-rwxr-xr-x. 1 root root  293 Dec  7 03:06 pip
-rwxr-xr-x. 1 root root  301 Dec  7 03:06 pip-2.7
lrwxrwxrwx. 1 root root    9 Dec  7 03:06 python -> python2.7
lrwxrwxrwx. 1 root root    9 Dec  7 03:06 python2 -> python2.7
-rwxr-xr-x. 1 root root 7788 Dec  7 03:06 python2.7

And the main thing that activate does is:

PATH="$VIRTUAL_ENV/bin:$PATH"
export PATH

My guess is that you're using virtualenv that was installed for your /usr/local/bin/python2.7. That's the reason for the "Already using..." message. If that's the case, you don't need to pass --python because that virtualenv is already using it by default (check its shebang).

Still, since virtualenv creates a versionless executable and activate alters PATH, you should get /var/python_venv/testbox/bin/python as python.

• Since python is an alias in your case, and activate doesn't use aliases - you must have it set in your bash startup scripts.