For mlocate you can edit /etc/updatedb.conf to specify what to index. One trick I use is "locate -Ai" that lets you search for multiple patterns and makes it ca

For mlocate you can edit /etc/updatedb.conf to specify what to index. One trick I use is "locate -Ai" that lets you search for multiple patterns and makes it case insensitive. So you can use "locate -Ai linux .pdf" to search for all pdf files related to Linux. Also for gnome there is tracker which does search and indexing built into the system. I think by default its set for minimal use but it can be configured by the settings/search panel to index many locations. I haven't played with is much recently though.