[CentOS] YUM (DNF) Possible Confusion Centos 8

Thu Jan 23 02:18:37 UTC 2020
David G. Miller <dave at davenjudy.org>

On 1/22/20 11:04 AM, david wrote:
> At 08:05 PM 1/21/2020, you wrote:
>> > On 1/21/20 10:10 AM, david wrote:
>> >> At 08:52 AM 1/21/2020, David G. Miller wrote:
>> >>
>> >>
>> >>> On 1/21/20 9:35 AM, david wrote:
>> >>>> Folks
>> >>>>
>> >>>> In a test Centos 8 installation as a guest of VirtualBox on Windows
>> >>>> 10, I want to install ffmpeg, and support for exfat. They're not in
>> >>>> the standard distribution (as far as I know), so I issue as root:
>> >>>>
>> >>>>   yum -y --enablerepo rpmfusion-free-updates install ffmpeg
>> >>>> fuse-exfat exfat-utils
>> >>>>
>> >>>> and that works just fine.  The ffmpeg functionality works; I
>> >>>> haven't tested exfat yet.  However, later, as part of 
>> maintenance,
>> >>>> I want to get a list of everything that's installed, so I issue
>> >>>>
>> >>>>   yum list installed
>> >>>>
>> >>>> and the following diagnostics occur:
>> >>>> -------------------------------
>> >>>> Modular dependency problems:
>> >>>>
>> >>>> Â Problem 1: conflicting requests
>> >>>>   - nothing provides module(perl:5.26) needed by module
>> >>>> perl-App-cpanminus:1.7044:8010020191120175858:a9207fc6-0.x86_64
>> >>>> Â Problem 2: conflicting requests
>> >>>>   - nothing provides module(perl:5.26) needed by module
>> >>>> perl-DBD-MySQL:4.046:8010020191114030811:073fa5fe-0.x86_64
>> >>>> Â Problem 3: conflicting requests
>> >>>>   - nothing provides module(perl:5.26) needed by module
>> >>>> perl-DBD-SQLite:1.58:8010020191114033549:073fa5fe-0.x86_64
>> >>>> Â Problem 4: conflicting requests
>> >>>>   - nothing provides module(perl:5.26) needed by module
>> >>>> perl-DBI:1.641:8010020191113222731:16b3ab4d-0.x86_64
>> >>>> Â Problem 5: conflicting requests
>> >>>>   - nothing provides module(perl:5.26) needed by module
>> >>>> perl-YAML:1.24:8010020191114031501:a5949e2e-0.x86_64
>> >>>> Installed Packages
>> >>>> <long list follows>
>> >>>> ------------------------------
>> >>>>
>> >>>> By the way, cpanm works ok too.
>> >>>>
>> >>>>
>> >>>> My questions are:
>> >>>> What do these diagnostics tell me?  What am I supposed to do 
>> about
>> >>>> it?
>> >>>>
>> >>>> Thanks for your help
>> >>>>
>> >>>> David
>> >>>>
>> >>>>
>> >>> I think its telling you that perl is NOT installed but the listed
>> >>> perl modules are installed although it could be looking for
>> >>> specifically the 5.26 version of perl (since you mentioned the CPAN
>> >>> works).  What happens if you issue perl -v? perl gets 
>> installed as
>> >>> a dependency of logwatch as an example so a lot of people don't
>> >>> realize that they have perl installed whether they want it or not.
>> >>>
>> >>> Cheers,
>> >>> Dave
>> >>>
>> >>> --
>> >>> "They that can give up essential liberty to obtain a little 
>> temporary
>> >>> safety deserve neither safety nor liberty."
>> >>>
>> >>> -- Benjamin Franklin
>> >>
>> >>
>> >> Perl is explicitly installed,  "perl -v" identifies v5.26.3, and 
>> comes
>> >> from the standard Centos 8 repositories.  So, I suspect your
>> >> interpretation doesn't fit the facts.
>> >> David K
>> >> _______________________________________________
>> >> CentOS mailing list
>> >> CentOS at centos.org
>> >> https://lists.centos.org/mailman/listinfo/centos
>> > Not seeing that here but it appears you are running newer versions 
>> of at
>> > least perl-DBD-MySQL, perl-DBD-SQLite and perl-DBI (snipped from "yum
>> > list installed" on my CentOS 8 VM after running "yum update"):
>> >
>> > perl-DBD-MySQL.x86_64                     
>> 4.023-6.el7 @anaconda
>> > perl-DBD-SQLite.x86_64                    
>> 1.39-3.el7 @anaconda
>> > perl-DBI.x86_64                           
>> 1.627-4.el7 @anaconda
>> >
>> > What repo are you pulling the listed packages from?  Is it the 
>> same repo
>> > as for perl?  I'm getting:
>>
>> Maybe it's worth to have a look a yum.log to see what happened to 
>> perl in
>> the history of the installation?
>>
>> Simon
>
>
> Simon and others
> Here's a very simple and hopefully reproducible test-case
>
> Select as your boot ISO:
>  CentOS-8.1.1911-x86_64-dvd1.iso
> Choose to reclaim all space on the disk
> Choose 'Minimal Install' as the software selection
> Connect yourself to the network (I use a wired connection) 
> perl-App-cpanminus
> Don't bother creating a user, just provide your root password.
> complete the install.
>
> After the reboot, issue as root:
>   yum -y install perl chrony perl-libwww-perl perl-App-cpanminus gcc
>
> When that is complete, issue:
>   yum list installed >nul
> and you get conflicting requests as follows:
>
> ----------------------------
> Modular dependency problems:
>
>  Problem 1: conflicting requests
>   - nothing provides module(perl:5.26) needed by module 
> perl-App-cpanminus:1.7044:8010020191120175858:a9207fc6-0.x86_64
>  Problem 2: conflicting requests
>   - nothing provides module(perl:5.26) needed by module 
> perl-YAML:1.24:8010020191114031501:a5949e2e-0.x86_64
> ----------------------------
>
> This doesn't seem like the expected results from a clean install.
> No changes were made in the repo files as supplied on the boot disc.
>
> David
>
>
>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos
OK.  Recreated the issue here.

Interestingly, perl-DBI and perl-DBD-SQLite did not have an issue with 
"nothing provides module(perl:5.26)" until I installed perl-App-cpanimus 
and perl-YAML which pulled in perl 5.26 (and ~90 other dependencies).  
They now show up as not being able to find module(perl:5.26) when I do a 
yum list installed.

Also, perl-App-cpanimus and perl-YAML report perl 5.26 as not provided 
and these are the modules that pulled in perl 5.26.  I looked at the 
appropriate provides and requires for each package with rpm and don't 
see anything that jumps out at me.

Have you tried using these modules in a perl program?  Wondering if it's 
a dnf or rpm dependency coding problem but everything works when you try 
to use it.  A missing dependency should cause the install to fail.

Cheers,
Dave

-- 
"They that can give up essential liberty to obtain a little temporary safety deserve neither safety nor liberty."

-- Benjamin Franklin