You might have both versions of Python, but the version 2 is probably first in the search path. For example, type “which python
”, then “ls -l /usr/bin/python
” (I am guessing it is located there, adjust for what “which
” returns), and it probably is a symbolic link to “/usr/bin/python2.7
”. You might look to see which versions are available already via “ls /usr/bin/python*
”.
If version 3 is missing, search like this (FYI, “less
” is a pager which lets you scroll forward and back and search…just use “q
” to quit when done):
apt search python3 | less
To search for “python3...
” at the start of a line in “less
”:
/^python3
You will find there is a package named “python3
”, and you can install it like this if you don’t already have it:
sudo apt-get install python3
Incidentally, you can check for different releases like this, where the least detailed version will be a symbolic link, and eventually you get to the most detailed release version as the actual file. Try this:
which python
which python2
which python2.7
which python3
You can install both version 2 and 3 at the same time without issue. You might still find out you need to install the correct version of pip
, but you will see a message if you run into that need. In the same way you might have pip
, pip2
, or pip3
.
Instead of just typing “python
”, you can specifically type “python2
” or “python3
”. If you happen to have multiple version of something like python3
, but one in “/usr/bin/python3
” and another in “/usr/local/bin/python3
”, you can name the full path and get that exact file, for example:
/usr/bin/python3 --version
/usr/bin/python2 --version
python --version
At the top of python files you will see a comment (at least most of such files), called the “shebang”, and if no specific python interpreter is named, then this is what the fie will use:
#!/usr/bin/python
If you edit this to name a particular version, then it uses that:
#!/usr/bin/python3
Incidentally, if you want the symbolic link “/usr/bin/python
” to point to python3
instead of python2
, then you could do this (avoid doing this though if you don’t have a good reason for it):
cd /usr/bin
sudo ln -sf ./python3 python
Most of the time this is equivalent, but under some circumstances may differ:
cd /usr/bin
sudo ln -sf /usr/bin/python3 python
If you run into other issues feel free to ask, but someone else will need to answer questions specific to pytorch.