RPM pre/post/pre-un/post-un and behavior of $1

[Panu Matilainen]

On Mon, 16 Aug 2010, Amol P wrote:

> Hi all,
> Please have a look of RPM installation output when carried out for two
> diff version one after the another. The Installed version is obtained by
> "rpm -qa | grep mypkg" to check the version which got installed after any
> rpm -i/-U comand.
> 
> --------------------------------------------------------------------------------
> ----------
> #1 rpm -Uvh mypkg-2010.05.1.18.noarch.rpm
> -PRE-IN:$1=1
> -POST-IN:1=1 
> -Installed Version: mypkg-2010.05.1.18.noarch 
> --------------------------------------------------------------------------------
> ----------
> #2 rpm -Uvh mypkg-2010.05.2.2.noarch.rpm
> - PRE-IN:$1=2  
> - POST-IN:$1=2  
> - PRE-UN:$1=1  
> - POST-UN:$1=1  
> - Installed Version: mypkg-2010.05.2.2.noarch
> --------------------------------------------------------------------------------
> ----------
> #3 rpm -Uvh mypkg-2010.05.2.2.noarch.rpm --force
> - PRE-IN:$1=2  
> - POST-IN:$1=2  
> - Installed Version: mypkg-2010.05.2.2.noarch
> --------------------------------------------------------------------------------
> ----------
> #4 rpm -ivh mypkg-2010.05.1.18.noarch.rpm --force
> - PRE-IN:$1=2  
> - POST-IN:$1=2  
> - Installed Version: mypkg-2010.05.1.18.noarch, mypkg-2010.05.2.2.noarch
> --------------------------------------------------------------------------------
> ----------
> #5 rpm -ivh mypkg-2010.05.2.2.noarch.rpm --force
> - PRE-IN:$1=3  
> - POST-IN:$1=3  
> - Installed Version: mypkg-2010.05.1.18.noarch, mypkg-2010.05.2.2.noarch
> --------------------------------------------------------------------------------
> ----------
> 
> In observation #4, why both versions are in RPM database. Any other way
> by which we can remove the higher version package when we are trying to
> install/update the lower version package

Because you're installing, not upgrading. Rpm permits several versions of 
a single package to be installed simultaneously if you install instead of 
upgrading (typically used for the kernel package).

> In observation #5, a new player comes in $1=3. Is it new feature or
> some strange.

It's basically an artifact of using --force.

> Also, how to remove the newer package & its installed stuff, when I am
> trying to install/update a LOWER version package forcefully. Is it
> possible or some tweaking required?

If you're using rpm cli to do the job, you can use --oldpackage to tell 
rpm to downgrade:

[root at dhcp102 noarch]# rpm -Uvh foo-0.2-1.noarch.rpm
Preparing...                ########################################### 
[100%]
    1:foo                    ########################################### 
[100%]
[root at dhcp102 noarch]# rpm -q foo
foo-0.2-1.noarch
[root at dhcp102 noarch]# rpm -Uvh --oldpackage foo-0.1-1.noarch.rpm
Preparing...                ########################################### 
[100%]
    1:foo                    ########################################### 
[100%]
[root at dhcp102 noarch]# rpm -q foo
foo-0.1-1.noarch

The more generic answer though: use an epoch to override the normal 
version comparsion, making the older package "win" the version comparison, 
so regular update without special cli-switches will work.

 	- Panu -