Two versions of python on linux how to make 2 7 the default

Question

I ve got two versions of python on my linuxbox    python Python 2 6 6  r266 84292  Jul 10 2013  22 48 45    GCC 4 4 7 20120313  Red Hat 4 4 7-3   on linux2 Type  help    copyright    credits  or  license  for more information   gt  gt  gt        usr local bin python2 7 Python 2 7 3  default  Oct  8 2013  15 53 09    GCC 4 4 7 20120313  Red Hat 4 4 7-3   on linux2 Type  help    copyright    credits  or  license  for more information   gt  gt  gt      which python  usr bin python   ls -al  usr bin python -rwxr-xr-x  2 root root 4864 Jul 10 22 49  usr bin python   How can I make 2 7 be the default version so when I type python it puts me in 2 7

User · Answer

Enter the command  which python    output   usr bin python  cd  usr bin ls -l   Here you can see something like this  lrwxrwxrwx 1 root   root            9 Mar  7 17 04  python - gt  python2 7   your default python2 7 is soft linked to the text  python   So remove the softlink python  sudo rm -r python   then retry the above command  ls -l   you can see the softlink is removed  -rwxr-xr-x 1 root   root      3670448 Nov 12 20 01  python2 7   Then create a new softlink for python3 6  ln -s  usr bin python3 6 python  Then try the command python in terminal    output  Python 3 6 7  default  Oct 22 2018  11 32 17    GCC 8 2 0  on linux   Type help  copyright  credits or license for more information

User · Answer

All OS comes with a default version of python and it resides in  usr bin  All scripts that come with the OS  e g  yum  point this version of python residing in  usr bin  When you want to install a new version of python you do not want to break the existing scripts which may not work with new version of python    The right way of doing this is to install the python as an alternate version   e g  wget http   www python org ftp python 2 7 3 Python-2 7 3 tar bz2  tar xf Python-2 7 3 tar bz2 cd Python-2 7 3   configure --prefix  usr local  make  amp  amp  make altinstall   Now by doing this the existing scripts like yum still work with  usr bin python  and your default python version would be the one installed in  usr local bin  i e  when you type python you would get 2 7 3  This happens because   PATH variable has  usr local bin before usr bin    usr lib64 qt-3 3 bin  usr local sbin  usr local bin  sbin  bin  usr sbin  usr bin  root bin   If python2 7 still does not take effect as the default python version you would need to do   export PATH   usr lib64 qt-3 3 bin  usr local sbin  usr local bin  sbin  bin  usr sbin  usr bin  root bin

User · Answer

You probably don t actually want to change your default Python   Your distro installed a standard system Python in  usr bin  and may have scripts that depend on this being present  and selected by     usr bin env python  You can usually get away with running Python 2 6 scripts in 2 7  but do you want to risk it   On top of that  monkeying with  usr bin can break your package manager s ability to manage packages  And changing the order of directories in your PATH will affect a lot of other things besides Python   In fact  it s more common to have  usr local bin ahead of  usr bin  and it may be what you actually want   but if you have it the other way around  presumably there s a good reason for that    But you don t need to change your default Python to get the system to run 2 7 when you type python     First  you can set up a shell alias   alias python  usr local bin python2 7   Type that at a prompt  or put it in your    bashrc if you want the change to be persistent  and now when you type python it runs your chosen 2 7  but when some program on your system tries to run a script with  usr bin env python it runs the standard 2 6     Alternatively  just create a virtual environment out of your 2 7  or separate venvs for different projects   and do your work inside the venv

User · Answer

Verify current version of python by     python --version   then check python is symbolic link to which file       ll  usr bin python   Output Ex    lrwxrwxrwx 1 root root 9 Jun 16  2014  usr bin python - gt  python2 7    Check other available versions of python     ls  usr bin python    Output Ex    usr bin python      usr bin python2 7-config   usr bin python3 4          usr bin python3 4m-config   usr bin python3 6m          usr bin python3m  usr bin python2     usr bin python2-config     usr bin python3 4-config   usr bin python3 6           usr bin python3 6m-config   usr bin python3m-config  usr bin python2 7   usr bin python3            usr bin python3 4m         usr bin python3 6-config    usr bin python3-config      usr bin python-config   If want to change current version of python to 3 6 version edit file    bashrc   vim    bashrc   add below line in the end of file and save   alias python  usr local bin python3 6   To install pip for python 3 6    sudo apt-get install python3 6 python3 6-dev   sudo curl https   bootstrap pypa io ez setup py -o -   sudo python3 6   sudo easy install pip   On Success  check current version of pip     pip3 -V   Output Ex   pip 1 5 4 from  usr lib python3 dist-packages  python 3 6

User · Answer

I guess you have installed the 2 7 version manually  while 2 6 comes from a package   The simple answer is  uninstall python package   The more complex one is  do not install manually in  usr local  Build a package with 2 7 version and then upgrade   Package handling depends on what distribution you use

User · Answer

Add  usr local bin to your PATH environment variable  earlier in the list than  usr bin   Generally this is done in your shell s rc file  e g  for bash  you d put this in  bashrc   export PATH   usr local bin  PATH    This will cause your shell to look first for a python in  usr local bin  before it goes with the one in  usr bin    Of course  this means you also need to have  usr local bin python point to python2 7 - if it doesn t already  you ll need to symlink it

[python] Two versions of python on linux. how to make 2.7 the default

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