default python os x

[Uwe Rangs]

Hello,

how can I change the default version of python with os x 10.7.

Thanks,
Uwe

 

[Uwe Rangs]

My workflow at the moment is to set a link:
mv python python_old
ln -s /usr/local/bin/python3.2 python

But is this a good idea?

-- Uwe

 

[Joel Goldstick]

Hello,

how can I change the default version of python with os x 10.7.

Thanks,
Uwe

You might want to look at this:

http://stackoverflow.com/questions/5846167/how-to-change-default-python-version

 

[Steven D'Aprano]

My workflow at the moment is to set a link: mv python python_old
ln -s /usr/local/bin/python3.2 python

But is this a good idea?

You should never change the system Python, since that runs the risk of
breaking system tools that expect a particular version. If there are any
system tools that run "python", they may break.

Instead, set a personal alias. For example, in my ~/.bashrc
file, I have the following:


export PYTHONPATH="/home/steve/python/:/home/steve/python/utilities"
export PYTHONSTARTUP=/home/steve/python/utilities/startup.py
alias python=python2.7
alias python3=python3.3
alias python1.5='env -u PYTHONSTARTUP python1.5'
alias python2.0='env -u PYTHONSTARTUP python2.0'
alias python2.1='env -u PYTHONSTARTUP python2.1'
alias python2.2='env -u PYTHONSTARTUP python2.2'
alias python2.3='env -u PYTHONSTARTUP python2.3'
alias python3.4="env -u PYTHONPATH ~/python/cpython/python"


So, for me, and me alone, typing "python" refers to Python 2.7 instead of
the system Python, which happens to be 2.4 on my server and 2.6 on my
laptop. "python1.5" etc unsets the startup file environment variable,
since my startup file assumes 2.4 or better. "python3.4" points to a
local copy in my home directory. Otherwise, python3.3, python3.2, etc.
work as expected.

 

[Uwe Rangs]

Ah, I see. Thank you!

You should never change the system Python, since that runs the risk of
breaking system tools that expect a particular version. If there are any
system tools that run "python", they may break.

Instead, set a personal alias. For example, in my ~/.bashrc
file, I have the following:


export PYTHONPATH="/home/steve/python/:/home/steve/python/utilities"
export PYTHONSTARTUP=/home/steve/python/utilities/startup.py
alias python=python2.7
alias python3=python3.3
alias python1.5='env -u PYTHONSTARTUP python1.5'
alias python2.0='env -u PYTHONSTARTUP python2.0'
alias python2.1='env -u PYTHONSTARTUP python2.1'
alias python2.2='env -u PYTHONSTARTUP python2.2'
alias python2.3='env -u PYTHONSTARTUP python2.3'
alias python3.4="env -u PYTHONPATH ~/python/cpython/python"


So, for me, and me alone, typing "python" refers to Python 2.7 instead of
the system Python, which happens to be 2.4 on my server and 2.6 on my
laptop. "python1.5" etc unsets the startup file environment variable,
since my startup file assumes 2.4 or better. "python3.4" points to a
local copy in my home directory. Otherwise, python3.3, python3.2, etc.
work as expected.

 

[Cameron Simpson]

| Ah, I see. Thank you!

Please don't top post. Thanks.

| On 2013-08-20 05:39:56 +0000, Steven D'Aprano said:
| >alias python1.5='env -u PYTHONSTARTUP python1.5'

I should point out that -u is a GNU env feature. It is not portable,
and in particular OSX "env" does not have it.

A shell function can do the same though:

py20() {
( unset PYTHONSTARTUP
exec python2.0 ${1+"$@"}
)
}

I've said py20 instead of python2.0 primarily because bash is a
bit... picky about function names and rejected the ".".

Cheers,