不同应用可能需要不同版本的 gcc，而且可能遇到gcc 某些版本无法安装的情况，本文记录相关内容。
背景
安装cuda开发库之后，使用gcc编译会可能会报错要求gcc版本，如下表
CUDA version
max supported GCC version
11.1, 11.2, 11.3
10
11
9
10.1, 10.2
8
9.2, 10.0
7
9.0, 9.1
6
8
5.3
7
4.9
5.5, 6
4.8
4.2, 5
4.6
4.1
4.5
4.0
4.4
我当前 gcc 的版本为 11.4, 但是需要安装 gcc 7的版本，但是安装时报错：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 > sudo apt install gcc-7 g++-7 Reading package lists... Done
Package gcc-7 is not available, but is referred to by another package.
E: Package 'gcc-7' has no installation candidate
而且同时我需要兼容保留多个 gcc 版本.
gcc 版本降级
遇到上述错误，原因为：使用的apt镜像库没有这个软件。
解决方案
添加 apt 库
1 sudo vim /etc/apt/sources.list
在最后添加
1 2 # stable add by , in order to install g++7 //archive.ubuntu.com/ubuntu focal main universe
更新 apt 库
重新安装 gcc g++
1 sudo apt install gcc-7 g++-7
此时已经可以安装了
gcc 版本维护
使用 update-alternatives 设置 gcc 和 g++
update-alternatives 是ubuntu系统中专门维护系统命令链接符的工具，通过它可以很方便的设置系统默认使用哪个命令、哪个软件版本。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 ll /usr/bin/gcc*lrwxrwxrwx 1 root root 6 Aug 5 2021 /usr/bin/gcc -> gcc-11 lrwxrwxrwx 1 root root 23 May 13 2023 /usr/bin/gcc-11 -> x86_64-linux-gnu-gcc-11 lrwxrwxrwx 1 root root 23 May 13 2023 /usr/bin/gcc-12 -> x86_64-linux-gnu-gcc-12 lrwxrwxrwx 1 root root 22 Mar 26 2020 /usr/bin/gcc-7 -> x86_64-linux-gnu-gcc-7 lrwxrwxrwx 1 root root 9 Aug 5 2021 /usr/bin/gcc-ar -> gcc-ar-11 lrwxrwxrwx 1 root root 26 May 13 2023 /usr/bin/gcc-ar-11 -> x86_64-linux-gnu-gcc-ar-11 lrwxrwxrwx 1 root root 26 May 13 2023 /usr/bin/gcc-ar-12 -> x86_64-linux-gnu-gcc-ar-12 lrwxrwxrwx 1 root root 25 Mar 26 2020 /usr/bin/gcc-ar-7 -> x86_64-linux-gnu-gcc-ar-7 lrwxrwxrwx 1 root root 9 Aug 5 2021 /usr/bin/gcc-nm -> gcc-nm-11 lrwxrwxrwx 1 root root 26 May 13 2023 /usr/bin/gcc-nm-11 -> x86_64-linux-gnu-gcc-nm-11 lrwxrwxrwx 1 root root 26 May 13 2023 /usr/bin/gcc-nm-12 -> x86_64-linux-gnu-gcc-nm-12 lrwxrwxrwx 1 root root 25 Mar 26 2020 /usr/bin/gcc-nm-7 -> x86_64-linux-gnu-gcc-nm-7 lrwxrwxrwx 1 root root 13 Aug 5 2021 /usr/bin/gcc-ranlib -> gcc-ranlib-11 lrwxrwxrwx 1 root root 30 May 13 2023 /usr/bin/gcc-ranlib-11 -> x86_64-linux-gnu-gcc-ranlib-11 lrwxrwxrwx 1 root root 30 May 13 2023 /usr/bin/gcc-ranlib-12 -> x86_64-linux-gnu-gcc-ranlib-12 lrwxrwxrwx 1 root root 29 Mar 26 2020 /usr/bin/gcc-ranlib-7 -> x86_64-linux-gnu-gcc-ranlib-7
gcc 已经安装的版本为 12, 11, 7
1 2 3 4 5 > ll /usr/bin/g++* 1 root root 6 Aug 5 2021 /usr/bin/g++ -> g++-11 1 root root 23 May 13 2023 /usr/bin/g++-11 -> x86_64-linux-gnu-g++-11 1 root root 23 May 13 2023 /usr/bin/g++-12 -> x86_64-linux-gnu-g++-12 1 root root 22 Mar 26 2020 /usr/bin/g++-7 -> x86_64-linux-gnu-g++-7
g++ 已经安装的版本为 12, 11, 7
1 2 3 sudo update-alternatives --install /usr/ bin/gcc gcc /u sr/bin/g cc-12 40 --slave /usr/ bin/g++ g++ /u sr/bin/g ++-12 /usr/ bin/gcc gcc /u sr/bin/g cc-11 50 --slave /usr/ bin/g++ g++ /u sr/bin/g ++-11 /usr/ bin/gcc gcc /u sr/bin/g cc-7 60 --slave /usr/ bin/g++ g++ /u sr/bin/g ++-7
其中40 ，50 ，60是优先级数值可以自己设定，–slave 能保证 gcc 和 g++ 保持相同的版本。
update-alternatives 配置 gcc 版本
1 sudo update - alternatives --config gcc
1 2 3 4 5 6 7 8 9 10 There are 3 choices for the alternative gcc (providing /usr/bin/gcc). Selection Path Priority Status ------------------------------------------------------------ * 0 /usr/bin/gcc-7 60 auto mode 1 /usr/bin/gcc-11 50 manual mode 2 /usr/bin/gcc-12 40 manual mode 3 /usr/bin/gcc-7 60 manual mode
Press <enter> to keep the current choice[*], or type selection number:
此时查看 gcc 的版本，可以看到已经变成 7.5.0 的版本
1 2 3 4 5 6 7 8 9 10 > gcc -vCOLLECT_GCC =gccCOLLECT_LTO_WRAPPER =/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapperOFFLOAD_TARGET_NAMES =nvptx-noneOFFLOAD_TARGET_DEFAULT =1.. /src/configure -v --with-pkgversion ='Ubuntu 7.5.0-6ubuntu2' --with-bugurl =file:///usr/share/doc/gcc-7/README.Bugs --enable-languages =c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix =/usr --with-gcc-major-version-only --program-suffix =-7 --program-prefix =x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir =/usr/lib --without-included-gettext --enable-threads =posix --libdir =/usr/lib --enable-nls --enable-bootstrap --enable-clocale =gnu --enable-libstdcxx-debug --enable-libstdcxx-time =yes --with-default-libstdcxx-abi =new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc =auto --enable-multiarch --disable-werror --with-arch-32 =i686 --with-abi =m64 --with-multilib-list =m32,m64,mx32 --enable-multilib --with-tune =generic --enable-offload-targets =nvptx-none --without-cuda-driver --enable-checking =release --build =x86_64-linux-gnu --host =x86_64-linux-gnu --target =x86_64-linux-gnu
1 sudo update - alternatives --config gcc
命令执行后，选择 1, 2, 或 3 可以选定当前使用的 gcc g++ 版本，比如我选择了 1
1 的前面会多个星星 *
1 2 3 4 5 6 Selection Path Priority Status ------------------------------------------------------------ 0 /usr/bin/gcc-7 60 auto mode * 1 /usr/bin/gcc-11 50 manual mode 2 /usr/bin/gcc-12 40 manual mode 3 /usr/bin/gcc-7 60 manual mode
此时 gcc 版本为 11
1 2 3 4 5 6 7 8 9 10 11 > gcc -vCOLLECT_GCC =gccCOLLECT_LTO_WRAPPER =/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapperOFFLOAD_TARGET_NAMES =nvptx-none:amdgcn-amdhsaOFFLOAD_TARGET_DEFAULT =1.. /src/configure -v --with-pkgversion ='Ubuntu 11.4.0-1ubuntu1~22.04' --with-bugurl =file:///usr/share/doc/gcc-11/README.Bugs --enable-languages =c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix =/usr --with-gcc-major-version-only --program-suffix =-11 --program-prefix =x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir =/usr/lib --without-included-gettext --enable-threads =posix --libdir =/usr/lib --enable-nls --enable-bootstrap --enable-clocale =gnu --enable-libstdcxx-debug --enable-libstdcxx-time =yes --with-default-libstdcxx-abi =new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking =release --with-target-system-zlib =auto --enable-objc-gc =auto --enable-multiarch --disable-werror --enable-cet --with-arch-32 =i686 --with-abi =m64 --with-multilib-list =m32,m64,mx32 --enable-multilib --with-tune =generic --enable-offload-targets =nvptx-none=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-gcn/usr --without-cuda-driver --enable-checking =release --build =x86_64-linux-gnu --host =x86_64-linux-gnu --target =x86_64-linux-gnu --with-build-config =bootstrap-lto-lean --enable-link-serialization =2
g++ 版本也为 11
1 2 3 4 5 6 7 8 9 10 11 > g++ -vCOLLECT_GCC =g++COLLECT_LTO_WRAPPER =/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapperOFFLOAD_TARGET_NAMES =nvptx-none:amdgcn-amdhsaOFFLOAD_TARGET_DEFAULT =1.. /src/configure -v --with-pkgversion ='Ubuntu 11.4.0-1ubuntu1~22.04' --with-bugurl =file:///usr/share/doc/gcc-11/README.Bugs --enable-languages =c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix =/usr --with-gcc-major-version-only --program-suffix =-11 --program-prefix =x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir =/usr/lib --without-included-gettext --enable-threads =posix --libdir =/usr/lib --enable-nls --enable-bootstrap --enable-clocale =gnu --enable-libstdcxx-debug --enable-libstdcxx-time =yes --with-default-libstdcxx-abi =new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking =release --with-target-system-zlib =auto --enable-objc-gc =auto --enable-multiarch --disable-werror --enable-cet --with-arch-32 =i686 --with-abi =m64 --with-multilib-list =m32,m64,mx32 --enable-multilib --with-tune =generic --enable-offload-targets =nvptx-none=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-XeT9lY/gcc-11-11.4.0/debian/tmp-gcn/usr --without-cuda-driver --enable-checking =release --build =x86_64-linux-gnu --host =x86_64-linux-gnu --target =x86_64-linux-gnu --with-build-config =bootstrap-lto-lean --enable-link-serialization =2
参考资料
文章链接：https://www.zywvvd.com/notes/system/linux/gcc-multi-version/gcc-multi-version/
