How do I find out which packages are already installed with yum.
The command you’re looking for is ‘yum list installed’ but you might want to combine it with grep or less because it’s most likely going to be a long list.
Look for php packages:
$ yum list installed | grep php
Just page the whole list:
$ yum list installed | less
Of course now that you know that, perhaps you want to know what packages are available to you:
$ yum list available | less
And of course you should check to see what needs to be updated on a regular basis:
yum list updates | less