很抱歉打扰您，但我遇到了一个似乎无法解决的问题。
我正在尝试在需要获得更多空间/内存的新服务器上安装 Postfix，旧服务器有 256MB 的 RAM 并且相当旧了。
我对此还很陌生，几乎花了今天/晚上的大部分时间来弄清楚如何让它工作。旧服务器已经MYSQL 5.5.36考虑到，如果我们更改为新服务器MariaDB并选择升级到MYSQL 5.7.18新服务器，可能会出现意外问题。我们实际上没有专门的开发运营团队，所以我不能听从他们的意见。
这是我的错误：
yum install postfix
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.seas.harvard.edu
* epel: epel.mirror.constant.com
* extras: ftp.osuosl.org
* updates: mirror.trouble-free.net
* webtatic: us-east.repo.webtatic.com
Resolving Dependencies
--> Running transaction check
---> Package postfix.x86_64 2:2.10.1-6.el7 will be installed
--> Processing Dependency: libmysqlclient.so.18(libmysqlclient_18)(64bit) for package: 2:postfix-2.10.1-6.el7.x86_64
Package 1:mariadb-libs-5.5.52-1.el7.x86_64 is obsoleted by mysql-community-libs-compat-5.7.18-1.el5.x86_64 which is already installed
--> Processing Dependency: libmysqlclient.so.18()(64bit) for package: 2:postfix-2.10.1-6.el7.x86_64
Package 1:mariadb-libs-5.5.52-1.el7.x86_64 is obsoleted by mysql-community-libs-compat-5.7.18-1.el5.x86_64 which is already installed
--> Finished Dependency Resolution
Error: Package: 2:postfix-2.10.1-6.el7.x86_64 (base)
Requires: libmysqlclient.so.18()(64bit)
Available: 1:mariadb-libs-5.5.52-1.el7.x86_64 (base)
libmysqlclient.so.18()(64bit)
Error: Package: 2:postfix-2.10.1-6.el7.x86_64 (base)
Requires: libmysqlclient.so.18(libmysqlclient_18)(64bit)
Available: 1:mariadb-libs-5.5.52-1.el7.x86_64 (base)
libmysqlclient.so.18(libmysqlclient_18)(64bit)
You could try using --skip-broken to work around the problem
You could try running: rpm -Va --nofiles --nodigest
# yum install postfix --skip-broken
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: linux.cc.lehigh.edu
* epel: epel.mirror.constant.com
* extras: ftp.osuosl.org
* updates: mirror.solarvps.com
* webtatic: us-east.repo.webtatic.com
Resolving Dependencies
--> Running transaction check
---> Package postfix.x86_64 2:2.10.1-6.el7 will be installed
--> Processing Dependency: libmysqlclient.so.18(libmysqlclient_18)(64bit) for package: 2:postfix-2.10.1-6.el7.x86_64
Package 1:mariadb-libs-5.5.52-1.el7.x86_64 is obsoleted by mysql-community-libs-compat-5.7.18-1.el5.x86_64 which is already installed
--> Processing Dependency: libmysqlclient.so.18()(64bit) for package: 2:postfix-2.10.1-6.el7.x86_64
Package 1:mariadb-libs-5.5.52-1.el7.x86_64 is obsoleted by mysql-community-libs-compat-5.7.18-1.el5.x86_64 which is already installed
Packages skipped because of dependency problems:
2:postfix-2.10.1-6.el7.x86_64 from base
显然，我可以看到它们mariadb-libs已被库淘汰mysql-community，但我已经完全删除了？mariadb
yum remove mariadb-libs
Loaded plugins: fastestmirror
No Match for argument: mariadb-libs
No Packages marked for removal
无论如何，我可以通过以下方式修复此问题：
- 安装 Postfix 并继续
- 也许可以改用 Mariadb（我们这里有 PROD 数据，这会导致问题吗）
- 也许降级到 MYSQL 5.5（真的不想这样做，因为倒退并不理想）。
任何帮助都将不胜感激。用户目前无法从应用程序接收密码重置电子邮件。
提前致谢。
答案1
问题是您正在尝试安装 mysql-community-libs-compat-5.7.18-1。el5在 el7 系统上。您需要使用 el7 的软件包来获取正确的 libmysqlclient.so.18 库。
（答案已更新，我刚刚意识到您使用了错误的软件包版本）