python installed in ubuntu but python command not found

I have installed python 2.7 and python 3.7 in my ubuntu 18.04 but when i

type python it shows

  Command 'python' not found, but can be installed with:

  sudo apt install python3       
  sudo apt install python        
  sudo apt install python-minimal

  You also have python3 installed, you can run 'python3' instead.

but i already installed python.

Solution 1:

As suggested in comments, you could create an alias as follows:

alias python='python3'

by adding it to the ~/.bashrc file at the end of this file, exiting and reloading it in the current terminal using the next command: . ~/.bashrc

Or using linking:

As you can see below, my python points to python2, python2 points to python2.7.

To achieve the same, use sudo ln -s /usr/bin/python2.7 /usr/bin/python2 && sudo ln -s /usr/bin/python2 /usr/bin/python

If you want python pointing to 3th version, you could use the same, but the last command should be: sudo ln -s /usr/bin/python3 /usr/bin/python

Example

$ whereis python
python: /usr/bin/python3.7 /usr/bin/python2.7-config /usr/bin/python2.7 /usr/bin/python3.7m-config /usr/bin/python3.7-config /usr/bin/python /usr/bin/python3.7m /usr/lib/python3.7 /usr/lib/python2.7 /usr/lib/python3.8 /etc/python3.7 /etc/python2.7 /etc/python /usr/local/lib/python3.7 /usr/local/lib/python2.7 /usr/include/python3.7 /usr/include/python2.7 /usr/include/python3.7m /usr/share/python /usr/share/man/man1/python.1.gz
user@lenovo:~$ ls -ailh /usr/bin/python*
1446954 lrwxrwxrwx 1 root root    7 жов 10 14:32 /usr/bin/python -> python2
1446952 lrwxrwxrwx 1 root root    9 жов 10 14:32 /usr/bin/python2 -> python2.7
1465834 -rwxr-xr-x 1 root root 3,6M лис  7 12:07 /usr/bin/python2.7
1447155 lrwxrwxrwx 1 root root   33 лис  7 12:07 /usr/bin/python2.7-config -> x86_64-linux-gnu-python2.7-config
1447156 lrwxrwxrwx 1 root root   16 жов 10 14:32 /usr/bin/python2-config -> python2.7-config
1442842 lrwxrwxrwx 1 root root    9 лют 12 00:23 /usr/bin/python3 -> python3.7
1449245 -rwxr-xr-x 2 root root 4,9M лис 20 11:21 /usr/bin/python3.7
1447339 lrwxrwxrwx 1 root root   33 лис 20 11:21 /usr/bin/python3.7-config -> x86_64-linux-gnu-python3.7-config
1449245 -rwxr-xr-x 2 root root 4,9M лис 20 11:21 /usr/bin/python3.7m
1447340 lrwxrwxrwx 1 root root   34 лис 20 11:21 /usr/bin/python3.7m-config -> x86_64-linux-gnu-python3.7m-config
1447341 lrwxrwxrwx 1 root root   16 жов  2 15:31 /usr/bin/python3-config -> python3.7-config
1442843 -rwxr-xr-x 1 root root  384 січ 30  2019 /usr/bin/python3-futurize
1442847 lrwxrwxrwx 1 root root   10 лют 12 00:23 /usr/bin/python3m -> python3.7m
1447342 lrwxrwxrwx 1 root root   17 жов  2 15:31 /usr/bin/python3m-config -> python3.7m-config
1442844 -rwxr-xr-x 1 root root  388 січ 30  2019 /usr/bin/python3-pasteurize
1447157 lrwxrwxrwx 1 root root   14 жов 10 14:32 /usr/bin/python-config -> python2-config
1455649 lrwxrwxrwx 1 root root   58 лип 10  2019 /usr/bin/pythontex -> ../share/texlive/texmf-dist/scripts/pythontex/pythontex.py
1450999 -rwxr-xr-x 1 root root  306 лип 10  2019 /usr/bin/pythontex3

Solution 2:

This solution only applies to Ubuntu 20.04 (but sometimes people looks at "similar issues" for a solution)

I had the same error with Ubuntu 20.04, in the case you like "python" to refer to "python3", you can simply install python-is-python3:

sudo apt-get install python-is-python3

After this, invoking python will work just fine