Installing and switching gcc/g++ versions in Debian

Option #1 – Uninstall older versions

This is sometimes not an option, because lots of dependencies will be uninstalled which you might need, or you want to keep those versions around for compiling stuff that still uses them.

Option #2 – Use update-alternatives to switch versions

This informative post describes it pretty well. I’ll sum it up here. First remove all update-alternatives:

sudo update-alternatives --remove-all gcc
sudo update-alternatives --remove-all g++

Now add update-alternatives for 4.6 and 4.7 and make the g++ configuration a slave of the gcc configuration, so that when you switch the gcc version, the g++ version is automagically switched too:

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.6 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.6
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.7 40 --slave /usr/bin/g++ g++ /usr/bin/g++-4.7

You can now switch compiler versions with:

sudo update-alternatives --config gcc

Option #3 – Use a script to switch versions

This script by Jeff Carr-3 can switch compiler versions for you:

#!/bin/bash 
usage() {
        echo 
        echo Sets the default version of gcc, g++, etc
        echo Usage:
        echo 
        echo "    gcc-set-default-version "
        echo 
        exit
}
cd /usr/bin
if [ -z $1 ] ; then 
        usage;
fi 
set_default() {
        if [ -e "$1-$2" ] ; then 
                echo $1-$2 is now the default
                ln -sf $1-$2 $1
        else 
                echo $1-$2 is not installed
        fi
}
for i in gcc cpp g++ gcov gccbug ; do 
        set_default $i $1
done

Download it and make it executable:

chmod 755 gcc-set-default-version

You can  now switch compiler versions with it:

sudo sh gcc-set-default-version 4.7

Voila. Works on Raspberry Pi too. Happy compiling!