背景
项目当前使用的ubuntu版本是 18.04（如何查看当前linux版本见文章最后）, 默认安装的gcc版本是7.5.0， 在这环境编译出来的deb包在银河麒麟v10 sp1系统上可以兼容，但是在银河麒麟v10 的OS上会出现兼容性的问（原因是银河麒麟v10上运行的deb需要使用gcc 5进行编译），因此需要在ubuntu 18.04版本上安装gcc 5 的版本
降级安装gcc 5
gcc 的安装有两种方式：
1、通过apt 包管理器进行安装
2、通过源码手动编译安装
ps:linux上可以gcc多版本共存
这里推荐使用第一种方式安装， 源码编译出错，需要安装一系列的依赖，比较复杂。
通过apt 包管理器进行安装
- 直接安装gcc、g 5.4.0 版本，提示找不到版本
ps:默认的软件源中不包含gcc 5.4.0 版本
root@d8b6c26946f0:/workspace# apt-get install gcc-5.4.0
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package gcc-5.4.0
E: Couldn't find any package by glob 'gcc-5.4.0'
E: Couldn't find any package by regex 'gcc-5.4.0'-
sources.list中添加软件源地址deb http://cz.archive.ubuntu.com/ubuntu bionic main universe其中cz.archive.ubuntu.com/ubuntu可换成国内的镜像源
// 我使用的软件源地址
deb https://mirrors.cloud.tencent.com/ubuntu/ bionic main universe之后update，后重新instll
代码语言：javascript复制root@d8b6c26946f0:/workspace# apt-get update
root@d8b6c26946f0:/workspace# apt-get install -y gcc-5
root@d8b6c26946f0:/workspace# apt-get install -y g -5安装完成后，系统中会同时存在gcc5 和 gcc7，还需要删除原有gcc链接，重新建立软链接，这样在使用gcc的时候使用的就是gcc5的版本了
- 查看本地gcc 情况
root@d8b6c26946f0:/usr/bin# ll |grep gcc
-rwxr-xr-x 1 root root 428 May 7 2006 c89-gcc*
-rwxr-xr-x 1 root root 454 Apr 11 2011 c99-gcc*
lrwxrwxrwx 1 root root 5 May 20 2019 gcc -> gcc-7*
-rwxr-xr-x 1 root root 907648 Apr 11 2018 gcc-5*
lrwxrwxrwx 1 root root 22 Dec 4 2019 gcc-7 -> x86_64-linux-gnu-gcc-7*
lrwxrwxrwx 1 root root 8 May 20 2019 gcc-ar -> gcc-ar-7*
-rwxr-xr-x 1 root root 31264 Apr 11 2018 gcc-ar-5*
lrwxrwxrwx 1 root root 25 Dec 4 2019 gcc-ar-7 -> x86_64-linux-gnu-gcc-ar-7*
lrwxrwxrwx 1 root root 8 May 20 2019 gcc-nm -> gcc-nm-7*
-rwxr-xr-x 1 root root 31264 Apr 11 2018 gcc-nm-5*
lrwxrwxrwx 1 root root 25 Dec 4 2019 gcc-nm-7 -> x86_64-linux-gnu-gcc-nm-7*
lrwxrwxrwx 1 root root 12 May 20 2019 gcc-ranlib -> gcc-ranlib-7*
-rwxr-xr-x 1 root root 31264 Apr 11 2018 gcc-ranlib-5*
lrwxrwxrwx 1 root root 29 Dec 4 2019 gcc-ranlib-7 -> x86_64-linux-gnu-gcc-ranlib-7*
-rwxr-xr-x 1 root root 2189 Nov 29 2019 gccmakedep*
lrwxrwxrwx 1 root root 5 May 20 2019 x86_64-linux-gnu-gcc -> gcc-7*
lrwxrwxrwx 1 root root 5 Apr 11 2018 x86_64-linux-gnu-gcc-5 -> gcc-5*
-rwxr-xr-x 1 root root 1047488 Dec 4 2019 x86_64-linux-gnu-gcc-7*
lrwxrwxrwx 1 root root 8 May 20 2019 x86_64-linux-gnu-gcc-ar -> gcc-ar-7*
lrwxrwxrwx 1 root root 8 Apr 11 2018 x86_64-linux-gnu-gcc-ar-5 -> gcc-ar-5*
-rwxr-xr-x 1 root root 31200 Dec 4 2019 x86_64-linux-gnu-gcc-ar-7*
lrwxrwxrwx 1 root root 8 May 20 2019 x86_64-linux-gnu-gcc-nm -> gcc-nm-7*
lrwxrwxrwx 1 root root 8 Apr 11 2018 x86_64-linux-gnu-gcc-nm-5 -> gcc-nm-5*
-rwxr-xr-x 1 root root 31200 Dec 4 2019 x86_64-linux-gnu-gcc-nm-7*
lrwxrwxrwx 1 root root 12 May 20 2019 x86_64-linux-gnu-gcc-ranlib -> gcc-ranlib-7*
lrwxrwxrwx 1 root root 12 Apr 11 2018 x86_64-linux-gnu-gcc-ranlib-5 -> gcc-ranlib-5*
-rwxr-xr-x 1 root root 31200 Dec 4 2019 x86_64-linux-gnu-gcc-ranlib-7*- 创建软链接 （gcc 重新升级到gcc7的话，重新创建这里的软链接就可以了）
cd /usr/bin
sudo rm -r gcc //移除之前的软链接
sudo ln -sf gcc-5 gcc // 建立gcc-5的软链接 此处尝试使用gcc-5.5.0，但是报错
sudo rm -r g //同上
sudo ln -sf g -5 g //同上- 检查gcc 版本
root@d8b6c26946f0:/usr/bin# gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.5.0-12ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c ,go,d,fortran,objc,obj-c --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --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 --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1) 相关Linux命令
1、查看ubuntu 版本 lsb_release -a
root@d8b6c26946f0:/# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.4 LTS
Release: 18.04
Codename: bionic2、 查看当前系统使用的内核版本： uname -r
root@d8b6c26946f0:/# uname -r
3.10.107-1-tlinux2_kvm_guest-00493、查看gcc版本:gcc --version
root@d8b6c26946f0:/# gcc --version
gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.4、当前ubuntu 使用的镜像源(使用的腾讯云镜像源)：cat /etc/apt/sources.list
root@d8b6c26946f0:/# cat /etc/apt/sources.list
deb https://mirrors.cloud.tencent.com/ubuntu/ focal main restricted universe multiverse
deb-src https://mirrors.cloud.tencent.com/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.cloud.tencent.com/ubuntu/ focal-security main restricted universe multiverse
deb-src https://mirrors.cloud.tencent.com/ubuntu/ focal-security main restricted universe multiverse
deb https://mirrors.cloud.tencent.com/ubuntu/ focal-updates main restricted universe multiverse
deb-src https://mirrors.cloud.tencent.com/ubuntu/ focal-updates main restricted universe multiverse
deb https://mirrors.cloud.tencent.com/ubuntu/ focal-backports main restricted universe multiverse
deb-src https://mirrors.cloud.tencent.com/ubuntu/ focal-backports main restricted universe multiverse
## Not recommended
# deb https://mirrors.cloud.tencent.com/ubuntu/ focal-proposed main restricted universe multiverse
# deb-src https://mirrors.cloud.tencent.com/ubuntu/ focal-proposed main restricted universe multiverse参考文章：https://packages.ubuntu.com/bionic/amd64/gcc-5/download
