I have set alias python=python3.4. but still when I write python in terminal it executes as version 2.7.
python3.4 only works in the terminal window where alias python=python3.4 is set.
Please help.
Thanks in advance.
Setting an alias is essentially a user shortcut and does not affect your environment outside of your terminal(see description of 'alias' here). Your question doesn't explain what the 'end goal' is, so I'll answer the two I can think of.
If you only interested in a shortcut:Don't do it! Just use 'python3.4' - it's 3 more keystrokes...
If you want to use version 3.4 by default outside your terminal:
First, you need to do is change the symlink of /usr/bin/python to point to the correct python version.
unalias python
ls -al $(which python)
Output should be something like:
lrwxrwxrwx 1 root root 9 Jan 01 00:01 /usr/bin/python -> python2.7
You need to change the link ("/usr/bin/python") to point to the python3.4 version:
sudo ln -f -v /usr/bin/python3.4 /usr/bin/python
IMPORTANT - you are changing the executable python version universally! Be sure you don't have any applications that depend on the older version's libraries. If, for example, you've installed the libpython2.7-dev package, then this is a CRAY CRAY BAD IDEA! Never mix versions of executables and build resources or you will get weird behavior...