I screwed up the system version of Python Pip on Ubuntu 12.10

I had the same message on linux.

/usr/bin/pip: No such file or directory

but then checked which pip was being called.

$ which pip
/usr/local/bin/pip 

On my debian wheezy machine I fixed it doing following...

/usr/local/bin/pip uninstall pip  
apt-get remove python-pip  
apt-get install python-pip  

====================================
This was due to mixup installing with apt-get and updating with pip install -U pip.

These also installed libraries at 2 different places which caused problems for me.

/usr/lib/python2.7/dist-packages  
/usr/local/lib/python2.7/dist-packages

Before getting happy with apt-get removes and installs. It's worthwhle to reset your bash cache.

hash -r

Bash will cache the path to pip using the distrubtion install (apt-get) which is /usr/bin/pip. If you're still in the same shell session, due to the cache, after updating pip from pip your shell will still look in /usr/bin/ and not /usr/local/bin/

for example:

$apt-get install python-pip
$which pip
/usr/bin/pip

$pip install -U pip
$which pip
/usr/bin/pip

$hash -r
$which pip
/usr/local/bin/pip

I had the same problem running Mint 18.1 after upgrading pip. I got it resolved simply by closing and opening the terminal.