[CentOS] A newbie question about searching an installed packet

Thu Nov 8 21:28:07 UTC 2018
Pierre Malard <plm at teledetection.fr>


I was sure there were a relevant solution. That’s exactly what I was looking for :-)

> Le 8 nov. 2018 à 21:02, Kenneth Porter <shiva at sewingwitch.com> a écrit :
> On 11/8/2018 11:52 AM, Pierre Malard wrote:
>> As write in subject, I’m a newbie about CentOS an all RedHat declines. I wrote a Shell script for ours Debians (all sort of Debian like) which verify which packets are present before running. I thought I had found an equivalent with « yum list installed | grep <packet> » command but I have sometime alerts about a lock because an other instance of « yum » is running.
> Yum is a layer on top of the RPM package database. Yum manages dependencies and figures out which additional packages to install (or remove) when you want to install a new package. Yum regularly runs a cron job to check for updates to existing packages and that cron job locks the yum database. That's probably why your interactive job complains that it can't lock the database.
> To just query what's installed, you can use the lower-level RPM commands. They don't require a lock on the yum database. The RPM database is only locked when you actually install or remove a package.
> I use this to see if a package is installed:
> rpm -qa | grep -i package-name
> I use the same command when I can't remember the exact name and capitalization of a package. That's why I include the -i in the grep command.
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Pierre Malard

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