https://askubuntu.com/questions/26498/choose-gcc-and-g-version
https://*.com/questions/7832892/how-to-change-the-default-gcc-compiler-in-ubuntu
https://codeyarns.com/2015/02/26/how-to-switch-gcc-version-using-update-alternatives/
关于 update-alternatives 命令的帮助: http://www.cnblogs.com/welhzh/p/7339632.html
First erased the current update-alternatives setup for gcc and g++:
sudo update-alternatives --remove-all gcc
sudo update-alternatives --remove-all g++
Install Packages
It seems that both gcc-4.3 and gcc-4.4 are installed after install build-essential. However, we can explicitly install the following packages:
sudo apt-get install gcc-4.3 gcc-4.4 g++-4.3 g++-4.4
Install Alternatives
Symbolic links cc and c++ are installed by default. We will install symbol links for gcc and g++, then link cc and c++ to gcc and g++ respectively.
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.3 10
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.4 20
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.3 10
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.4 20
sudo update-alternatives --install /usr/bin/cc cc /usr/bin/gcc 30
sudo update-alternatives --set cc /usr/bin/gcc
sudo update-alternatives --install /usr/bin/c++ c++ /usr/bin/g++ 30
sudo update-alternatives --set c++ /usr/bin/g++
Configure Alternatives
The last step is configuring the default commands for gcc, g++. It's easy to switch between 4.3 and 4.4 interactively:
sudo update-alternatives --config gcc
sudo update-alternatives --config g++
Or switch using script:
#!/bin/sh
if [ -z "$1" ]; then
echo "usage: $0 version" 1>&2
exit 1
fi
if [ ! -f "/usr/bin/gcc-$1" ] || [ ! -f "/usr/bin/g++-$1" ]; then
echo "no such version gcc/g++ installed" 1>&2
exit 1
fi
update-alternatives --set gcc "/usr/bin/gcc-$1"
update-alternatives --set g++ "/usr/bin/g++-$1"
Here's a complete example of jHackTheRipper's answer for the TL;DR crowd. :-) In this case, I wanted to run g++-4.5 on an Ubuntu system that defaults to 4.6. As root:
apt-get install g++-4.5
update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.6 100
update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.5 50
update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.6 100
update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.5 50
update-alternatives --install /usr/bin/cpp cpp-bin /usr/bin/cpp-4.6 100
update-alternatives --install /usr/bin/cpp cpp-bin /usr/bin/cpp-4.5 50
update-alternatives --set g++ /usr/bin/g++-4.5
update-alternatives --set gcc /usr/bin/gcc-4.5
update-alternatives --set cpp-bin /usr/bin/cpp-4.5Here, 4.6 is still the default (aka "auto mode"), but I explicitly switch to 4.5 temporarily (manual mode). To go back to 4.6:
update-alternatives --auto g++
update-alternatives --auto gcc
update-alternatives --auto cpp-bin(Note the use of cpp-bin instead of just cpp. Ubuntu already has a cpp alternative with a master link of /lib/cpp. Renaming that link would remove the /lib/cpp link, which could break scripts.)