I can\'t use pip3 though python3-pip has already been installed. How to solve the problem?
sudo pip3 install virtualenv
sudo: pip3: command not found
sudo apt-g
There is no need to install virtualenv. Just create a workfolder and open your editor in it. Assuming you are using vscode,
$mkdir Directory && cd Directory
$code .
It is the best way to avoid breaking Ubuntu/linux dependencies by messing around with environments. In case anything goes wrong, you can always delete that folder and begin afresh. Otherwise, messing up with the ubuntu/linux python environments could mess up system apps/OS (including the terminal). Then you can press shift+P and type python:select interpreter. Choose any version above 3. After that you can do
$pip3 -v
It will display the pip version. You can then use it for installations as
$pip3 install Library