What's the difference between python shebangs with /usr/bin/env rather than hard-path?

Question

I used to use the shebang

#!/usr/bin/env python

When is it better to use

#!/usr/bin/python

What is the exact difference between them?

possible duplicate of Why do people write #!/usr/bin/env python on the first line of a Python script? — dnozay
– dnozay, Commented Oct 10, 2013 at 18:54
Possible duplicate of Should I put #! (shebang) in Python scripts, and what form should it take? — codeaviator
– codeaviator, Commented Sep 22, 2017 at 2:04

manojlds · Accepted Answer · 2011-04-19 05:37:07Z

101

#!/usr/bin/python is hardcoded to always run /usr/bin/python, while #!/usr/bin/env python will run whichever python would be default in your current environment (it will take in account for example $PATH, you can check which python interpreter will be used with which python).

The second way ( #!/usr/bin/env python ) is preferred , as it's not dependent on particular installation. It will work for example with virtualenv setups or systems where there is no /usr/bin/python, but only e.g. /usr/local/bin/python.

edited Apr 19, 2011 at 5:37

manojlds

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answered Apr 18, 2011 at 22:28

vartec

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Blair Over a year ago

This. See Why do people write #!/usr/bin/env python on the first line of a Python script? and this message on the Python mailing list.

ncoghlan Over a year ago

Indirection via env also works when /usr/bin/python exists, but isn't an actual executable (e.g. it may be a launch script)

Ken Over a year ago

does that imply that it is better to use #!/usr/bin/env perl will be more versatile than the usual shebang #!/bin/perl? It seems to me that people usually use #!/bin/perl in perl, but #!/usr/bin/env python for python. Why?

dubiousjim Over a year ago

@Ken, no principled reason, just accidents of history.

vartec Over a year ago

@Ken: AFAIK, there isn't popular equivalent of virtualenv for Perl.

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