macOS Installed Python 3.1. Terminal still launches 2.5.1.

Caezar · Aug 7, 2009

Thread title says it all

I installed Python 3.1, but when I type python in the terminal, it launches python 2.5.1.

Can the two version coexist?
Can I uninstall 2.5.1?
If I can, should I?

iShater · Aug 7, 2009

Yes they can. Most likely each one went to a directory that has the version number in it's name.

Which one is in your PATH? that would be the one that gets launched.

Caezar · Aug 7, 2009

iShater said:
Which one is in your PATH? that gets launched.

What do you mean by my Path?

Mitthrawnuruodo · Aug 7, 2009

In the Terminal, type echo $PATH and see if there's any Python references there.

Caezar · Aug 7, 2009

Mitthrawnuruodo said:
In the Terminal, type echo $PATH and see if there's any Python references there.

This is what I get:
/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin

GroovyLinuxGuy · Aug 7, 2009

Caezar said:
Thread title says it all

I installed Python 3.1, but when I type python in the terminal, it launches python 2.5.1.

Can the two version coexist?
Can I uninstall 2.5.1?
If I can, should I?

The PATH is an environment variable that is a list of directories that the operating system looks in to find commands issued by the user

You may have to look where python was installed and use the full path to that version
The default version on python is found at /usr/bin/python (actually that's just a symlink to /System/Library/Frameworks/Python.framework/Versions/2.5/bin/python)

Depending on how you installed it you might want to check /usr/bin or even easier do a
locate python | less
in the terminal and just look for where it was installed

You can then use
#!/usr/bin/python3.1 (or where ever your interpreter is located)
on your shebang line

Personally I create an /opt directory and install any newer versions there and just symlink it back to /usr/bin but that's just me

Cheers and I hope that made sense...still working on first morning coffees

Caezar · Aug 7, 2009

Thanks.

Python 2.x is installed under /System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/

Python 3.x is installed under Macintosh HD/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/

Is there a way I can open the newer version from the terminal?

lee1210 · Aug 7, 2009

There are many ways. I would probably recommend (as the system probably likes 2.3 a lot) adding a symlink to /usr/local/bin called py3 or python3 or something like that like this:
sudo ln -s "/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/python" /usr/local/bin/py3
The path to the 3.1 python executable might not be quite right, so you can just sub it in.

Then when you want to use version 3, you'd just type py3. When you wanted the 2.3, just type python. I would not change, at the system level, which one gets called by default. If you really, really want to get version 3 by typing python, you could add an entry to your bath by editing your .bash_profile, like:
export PATH=/my/new/dir:$PATH

Then you can make a symlink called python in /my/new/dir. That way, when you ran python from the terminal it would find the version 3 executable before it found the version 2 one. I think this would let the system still use the python it likes by name, but someone may need to correct me on this.

-Lee

Caezar · Aug 7, 2009

Ok, I am out of my depth here. I'll forget the terminal and simply use IDLE.

Thanks everyone for you help. I learned a few things on the way.

Cromulent · Aug 7, 2009

The Python 3.1 Mac installer comes with a shell script which makes it the default Python to use on the Mac. Just run that and you will be sorted.

Caezar · Aug 7, 2009

Cromulent said:
The Python 3.1 Mac installer comes with a shell script which makes it the default Python to use on the Mac. Just run that and you will be sorted.

Are you referring to Update Shell Profile.command? I ran it to no avail.

Cinder6 · Aug 7, 2009

How did you install it? Did you download a package, or use MacPorts? Did you try typing 'python31'?

Cromulent · Aug 7, 2009

Caezar said:
Are you referring to Update Shell Profile.command? I ran it to no avail.

Sometimes you need to log out and log back in again for changes to the path to take effect. Try that.

wrldwzrd89 · Aug 7, 2009

Cromulent said:
Sometimes you need to log out and log back in again for changes to the path to take effect. Try that.

A simple restart of the Terminal is often all that's needed to make path changes take effect - not a full log out and back in.

Cromulent · Aug 7, 2009

wrldwzrd89 said:
A simple restart of the Terminal is often all that's needed to make path changes take effect - not a full log out and back in.

Normally you are right, but I have had instances were I have to do a full log out and back in again for changes to register. Normally that is when I am editing existing path entries rather than adding completely new ones though.

Caezar · Aug 7, 2009

Still no luck. I shut down my Mac, had a shower , brushed my teeth, went to bed, slept, woke up, turned my Mac back on, launched the terminal and went I type Python, it still launches 2.5.1.

How did I install: downloaded an image from http://www.python.org and opened the package.

MikhailT · Aug 7, 2009

Caezar said:
Still no luck. I shut down my Mac, had a shower , brushed my teeth, went to bed, slept, woke up, turned my Mac back on, launched the terminal and went I type Python, it still launches 2.5.1.

How did I install: downloaded an image from www.python.org and opened the package.

Dude, just type python and press tab to see a list of all python binary files. it is most likely python3.1.

The default will always remain 2.5.1 unless you update your config to point to 3.1 instead.

Libripens · Jun 20, 2012

Just Type "python3"

I installed Python 3.2.3, and I was having the same problem. Finally, I typed "python3" in terminal and it worked. If just type "python" I get the previous version though.

MorphingDragon · Jun 20, 2012

lee1210 said:
There are many ways. I would probably recommend (as the system probably likes 2.3 a lot) adding a symlink to /usr/local/bin called py3 or python3 or something like that like this:
sudo ln -s "/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/python" /usr/local/bin/py3
The path to the 3.1 python executable might not be quite right, so you can just sub it in.

Then when you want to use version 3, you'd just type py3. When you wanted the 2.3, just type python. I would not change, at the system level, which one gets called by default. If you really, really want to get version 3 by typing python, you could add an entry to your bath by editing your .bash_profile, like:
export PATH=/my/new/dir:$PATH

Then you can make a symlink called python in /my/new/dir. That way, when you ran python from the terminal it would find the version 3 executable before it found the version 2 one. I think this would let the system still use the python it likes by name, but someone may need to correct me on this.

-Lee

Most linux distros use python3 as an alias, so if you're writing cross platform scripts/apps I would suggest python3.

macOS Installed Python 3.1. Terminal still launches 2.5.1.

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