Question

My CentOS 5.5 server has both Python 2.4 and Python 2.7 installed (to /opt/python2.7.2). In my ~/.bash_profile I have two aliases pointing to my Python 2.7 install and my PATH configured as:

alias python=/opt/python2.7.2/bin/python
alias python2.7=/opt/python2.7.2/bin/python
PATH=$PATH:/opt/python2.7/bin

There’s also a symbolic link I created as well:

ln -sf /opt/python2.7.2/bin/python /usr/bin/python2.7

I have a Makefile which has the following lines:

pythonbuild:
        python setup.py build

To my surprise I found that Python 2.4 is being invoked and not Python 2.7.

I have to explicitly specify python2.7:

pythonbuild:
        python2.7 setup.py build

Are bash aliases ignored by make? I am guessing make uses PATH to locate the first python executable (which happens to be Python 2.4) instead?

Answer 1

From bash(1):

   Aliases are not expanded when the shell is not interactive,
   unless the expand_aliases shell option is set using shopt
   (see the description of shopt under SHELL BUILTIN COMMANDS
   below).

While you might be able to use something like SHELL=/bin/bash -O expand_aliases in your Makefile, I think keeping an explicit dependency upon the newer Python in your Makefile is much better than keeping the dependency hidden in your user ~/.bash_profile file.

Instead, put PYTHON=/opt/python2.7/bin/python into your Makefile, and then you can just use:

pythonbuild:
    $(PYTHON) setup.py build

in your rules.

The best part is you can easily change which Python interpreter you use on the command line:

make PYTHON=/tmp/python-beta/bin/python pythonbuild

If you deploy it to another site, it is just one line in the Makefile that needs to be updated.