These are a few I've only learned recently.
Ever needed to find out in which package a certain binary or file resides? The whatprovides option lets you do so. Let's assume you're looking for the package that contains 'ab' (the Apache Benchmark).
[root@dev ~]# yum whatprovides */ab httpd-2.2.3-43.el5.centos.x86_64 : Apache HTTP Server Repo : base Matched from: Filename : /usr/bin/ab
It's important to do the search for '*/ab' (including the star & dash), or you won't find anything. Now you know you need to install the 'httpd-2.2.3-43′ package to get it.
This one gets all credits to Rackerhacker!
yum grouplist, groupinfo & groupinstall
Say you're preparing a system to build your own RPM packages or compile your own tools. I previously just ran a "yum install <package>" for each package that I would need, but you can make this easier.
Via grouplist you list all grouped packages provided by yum.
[root@dev ~]# yum grouplist Installed Groups: [snip] Available Groups: [snip] Development Libraries Development Tools ...
If your're interested to know what's in the "Development Tools" group, you can run a yum groupinfo.
[root@dev ~]# yum groupinfo "Development Tools" Group: Development Tools Description: These tools include core development tools such as automake, gcc, perl, python, and debuggers. Mandatory Packages: autoconf automake binutils [snip] Default Packages: automake14 automake15 automake16 [snip] Optional Packages: ElectricFence ccache clips [snip]
And if that's what you need, you install it.
[root@dev ~]# yum groupinstall "Development Tools"
Knowing which repositories are enabled for yum, could mean checking out the files in /etc/yum.repos.d/*.repo, or it could be as simple as this.
[root@dev ~]# yum repolist repo id repo name status addons CentOS-5 - Addons enabled: 0 base CentOS-5 - Base enabled: 3,434 epel Extra Packages for Enterprise Linux 5 - x86_64 enabled: 6,192 extras CentOS-5 - Extras enabled: 297 updates CentOS-5 - Updates enabled: 1,135 repolist: 11,069
Feels easier that running through those files, personally.