CentOS - Dec 2018 - In centos, how to switch to default gcc after switched to a higher version of gcc with devtoolset.

I want to install several gcc with different versions in centos. The default
version of gcc in centos6 is 4.9.3. So I use devtoolset install a higher version
of gcc. Then I switch to the higher version of gcc by executing "source
/opt/rh/devtoolset-5/enable". But now if I want to switch back to the
default gcc, how should I do?
By the way, is there any solution to install multiple gcc with different
versions in centos 5?

On Sat, 2018-12-01 at 11:03 +0800, yf chu wrote:
> I want to install several gcc with different versions in centos. The
> default version of gcc in centos6 is 4.9.3. So I use devtoolset
> install a higher version of gcc. Then I switch to the higher version
> of gcc by executing "source /opt/rh/devtoolset-5/enable". But now
if
> I want to switch back to the default gcc, how should I do? 
Exit the shell and start a new one.

If you want to frequently shift between the different versions then
probably the best way is to use the instructions in the devtoolset docs
- i.e. do

  scl enable devtoolset-5 bash

This will start a shell with the correct environment. You can then just
terminate the shell that's just been started to get back the the
original environment.

> By the way, is there any solution to install multiple gcc with
> different versions in centos 5? 
> 
CentOS 5 is no longer a supported operating system - you should not be
using it since it hasn't had any security or bug fixes for a while. As
such you won't find any repositories with updated versions of software
for it.  The only way you are going to get updated versions of GCC on
it is by compiling them yourself - and even then you may need
dependencies that aren't available for such an old distro.

P.