yum shell - bat out of dependency hell

There's evil in the air and there's thunder in sky

(Meatloaf "Bat out of hell")

# yum install foo
[..]
Error: foo conflicts with bar

Again I have had the pleasure of having dependencies between RPM-packages ending my attempt to install a single package with a suggestion of removing core packages. I think this most often happen with Mysql or Percona packages, but I am sure MariaDB will be able to give you the same situation too. It's not the first time I have been here..

[root@ftp01-prod ~]# yum install Percona-Server-client-57
Loaded plugins: fastestmirror, priorities
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package Percona-Server-client-57.x86_64 0:5.7.20-19.1.el7 will be installed
--> Processing Dependency: Percona-Server-shared-57 for package: Percona-Server-client-57-5.7.20-19.1.el7.x86_64
--> Running transaction check
---> Package Percona-Server-shared-57.x86_64 0:5.7.20-19.1.el7 will be installed
--> Processing Dependency: Percona-Server-shared-compat-57 for package: Percona-Server-shared-57-5.7.20-19.1.el7.x86_64
--> Running transaction check
---> Package Percona-Server-shared-compat-57.x86_64 0:5.7.20-19.1.el7 will be installed
--> Processing Conflict: Percona-Server-shared-compat-57-5.7.20-19.1.el7.x86_64 conflicts Percona-Server-shared-56
--> Finished Dependency Resolution
Error: Percona-Server-shared-compat-57 conflicts with Percona-Server-shared-56-5.6.38-rel83.0.el7.x86_64
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest
[root@ftp01-prod ~]#

So if I want to install Percona-Server-client-57 I have to install Percona-Server-shared-compat-57 too, and that I can't because of the already installed Percona-Server-shared-56. OK, so I will just remove Percona-Server-shared-56 and then install Percona-Server-shared-compat-57 before doing the install I first tried to do:

[root@ftp01-prod ~]# yum remove Percona-Server-shared-56
[..]
Dependencies Resolved

================================================================================================================
 Package                           Arch            Version                      Repository                 Size
================================================================================================================
Removing:
 Percona-Server-shared-56          x86_64          5.6.38-rel83.0.el7           @percona-release          3.4 M
Removing for dependencies:
 MySQL-python                      x86_64          1.2.5-1.el7                  @centos_os                284 k
 fail2ban                          noarch          0.9.7-1.el7                  @epel                     0.0
 fail2ban-sendmail                 noarch          0.9.7-1.el7                  @epel                      11 k
 perl-DBD-MySQL                    x86_64          4.023-5.el7                  @centos_os                323 k
 postfix                           x86_64          2:2.10.1-6.el7               @centos_os                 12 M
 redhat-lsb-core                   x86_64          4.1-27.el7.centos.1          @anaconda                  45 k

Transaction Summary
================================================================================================================
Remove  1 Package (+6 Dependent packages)

Installed size: 16 M
Is this ok [y/N]:

Very much not OK. I'd like to at least keep things with descriptions like this

Description : The Linux Standard Base (LSB) Core module support
: provides the fundamental system interfaces, libraries,
: and runtime environment upon which all conforming
: applications and libraries depend.

The problem seems to be that Postfix needs libmysqlclient.so.18 which is provided by both Percona-Server-shared-56 and Percona-Server-shared-compat-57. So I just need to swap the former for the latter, and then I can run my original install.

OK, so I both want to remove a package and install a package. And I want to do it at the same time, so that I don't have to remove things like redhat-lsb-core. Did you notice the use of the word transaction in "Transaction Summary" from yum? A transaction is actually what I want. Luckily yum provides a way of doing this, and have probably done since forever, but I didn't learn about it till today. And as so many times before, it is a shell that solves our problems:

[root@ftp01-prod ~]# yum shell

Loaded plugins: fastestmirror, priorities

> remove Percona-Server-shared-56

> install Percona-Server-shared-compat-57

Loading mirror speeds from cached hostfile

> run

--> Running transaction check

---> Package Percona-Server-shared-56.x86_64 0:5.6.38-rel83.0.el7 will be erased

---> Package Percona-Server-shared-compat-57.x86_64 0:5.7.20-19.1.el7 will be installed

--> Finished Dependency Resolution

==================================================================================================

 Package                             Arch       Version                Repository            Size

==================================================================================================

Installing:

 Percona-Server-shared-compat-57     x86_64     5.7.20-19.1.el7        percona-release      1.2 M

Removing:

 Percona-Server-shared-56            x86_64     5.6.38-rel83.0.el7     @percona-release     3.4 M

Transaction Summary

==================================================================================================

Install  1 Package

Remove   1 Package

Total download size: 1.2 M

Is this ok [y/d/N]:

Yes, very much thank you! And then finally:

[root@ftp01-prod ~]# yum install Percona-Server-client-57

[..]

Dependencies Resolved

==================================================================================================

 Package                        Arch         Version                  Repository             Size

==================================================================================================

Installing:

 Percona-Server-client-57       x86_64       5.7.20-19.1.el7          percona-release       7.2 M

Installing for dependencies:

 Percona-Server-shared-57       x86_64       5.7.20-19.1.el7          percona-release       747 k

Transaction Summary

==================================================================================================

Install  1 Package (+1 Dependent package)

Total download size: 7.9 M

Installed size: 41 M

Is this ok [y/d/N]:y

[..]

Complete!

Done and done :-)