记录下安装pg过程中遇到的一个小问题：
[root@db-server1 yum.repos.d]# yum install readline-devel
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package readline-devel.x86_64 0:6.2-10.el7 will be installed
--> Processing Dependency: readline = 6.2-10.el7 for package: readline-devel-6.2-10.el7.x86_64
--> Processing Dependency: ncurses-devel for package: readline-devel-6.2-10.el7.x86_64
--> Running transaction check
---> Package ncurses-devel.x86_64 0:5.9-14.20130511.el7_4 will be installed
---> Package readline-devel.x86_64 0:6.2-10.el7 will be installed
--> Processing Dependency: readline = 6.2-10.el7 for package: readline-devel-6.2-10.el7.x86_64
--> Finished Dependency Resolution
Error: Package: readline-devel-6.2-10.el7.x86_64 (base)
Requires: readline = 6.2-10.el7
Installed: readline-6.2-11.el7.x86_64 (@base)
readline = 6.2-11.el7
Available: readline-6.2-10.el7.x86_64 (base)
readline = 6.2-10.el7
You could try using --skip-broken to work around the problem
You could try running: rpm -Va --nofiles --nodigest
[root@db-server2 yum.repos.d]# yum install ncurses-devel.x86_64
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package ncurses-devel.x86_64 0:5.9-14.20130511.el7_4 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
==================================================================================================================================================================
Package Arch Version Repository Size
==================================================================================================================================================================
Installing:
ncurses-devel x86_64 5.9-14.20130511.el7_4 base 712 k
Transaction Summary
==================================================================================================================================================================
Install 1 Package
Total download size: 712 k
Installed size: 2.1 M
Is this ok [y/d/N]: y
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : ncurses-devel-5.9-14.20130511.el7_4.x86_64 1/1
Verifying : ncurses-devel-5.9-14.20130511.el7_4.x86_64 1/1
Installed:
ncurses-devel.x86_64 0:5.9-14.20130511.el7_4
Complete!
手工安装好ncurses-devel后还是报错，如下：
[root@db-server1 ~]# yum install readline-devel.x86_64
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
base | 3.6 kB 00:00:00
Resolving Dependencies
--> Running transaction check
---> Package readline-devel.x86_64 0:6.2-10.el7 will be installed
--> Processing Dependency: readline = 6.2-10.el7 for package: readline-devel-6.2-10.el7.x86_64
--> Finished Dependency Resolution
Error: Package: readline-devel-6.2-10.el7.x86_64 (base)
Requires: readline = 6.2-10.el7
Installed: readline-6.2-11.el7.x86_64 (@base)
readline = 6.2-11.el7
Available: readline-6.2-10.el7.x86_64 (base)
readline = 6.2-10.el7
You could try using --skip-broken to work around the problem
You could try running: rpm -Va --nofiles --nodigest
遇到报错，本能进行度娘，网上基本都在讲是yum配置问题，一度怀疑自己配置的本地yum真的存在问题。按照网上的各种尝试无果，便重新看报错的字面意思：
提示要安装readline-devel.x86_64需要先安装readline-6.2，目前可以从配置的yum中可以获得的版本是readline-6.2-10.el7.x86_64 (base) readline-devel-6.2-10.el7.x86_64 (base)。
已经安装的版本为readline-6.2-11.el7.x86_64，再安装readline-devel-6.2-10.el7.x86_64这个版本无法安装上。
[root@db-server1 yum.repos.d]# rpm -aq readline* readline-6.2-11.el7.x86_64
知道了原因，问题就好解决了，第一种思路是对已经安装的readline-6.2-11.el7.x86_64进行降级到6.2.10版本，第二种思路是安装readline-devel的6.2.11版本。比较奇怪的一点是操作系统是centos7.6版本的，自己配置的本地yum源也是用的7.6版本的，至于为什么存在版本问题就不去深究了，从官网上下载对应的rpm包后成功解决。
https://centos.pkgs.org/7/centos-x86_64/readline-devel-6.2-11.el7.x86_64.rpm.html
[root@db-server1 postgres]# rpm -ivh readline-devel-6.2-11.el7.x86_64.rpm Preparing... ################################# [100%] Updating / installing... 1:readline-devel-6.2-11.el7 ################################# [100%]
总结：其实解决方法没有啥难度，关键是处理问题的方向，不能遇到问题拿到手就去网上搜，有时候仔细看下报错，自主思考一下，就很容易解决了。