$ locate XF86Config
This should be pretty fast. You’ll get a list of filenames that contain XF86Config, something like this:
/etc/X11/XF86Config
/usr/X11R6/lib/X11/XF86Config
/usr/X11R6/lib/X11/XF86Config.eg
/usr/X11R6/man/man5/XF86Config.5x.gz
Now try the find command:
$ find / -name XF86Config
You will hear a lot of disk activity, and this will take a lot longer. Results will look something like this:
/etc/X11/XF86Config
/usr/X11R6/lib/X11/XF86Config
find: /var/spool/cron/atjobs: Permission denied
find: /var/spool/cron/atspool: Permission denied
find: /var/lib/xdm/authdir: Permission denied
Notice that find found only files that were named exactly XF86Config, rather than any files containing that string of letters. Also, find actually tried to look in every directory on the system—including some where you didn’t have read permissions. That’s why you got the Permission denied messages.
The syntax is different as well. With find, you had to specify what directory to search in, whereas locate automatically chose the root directory. And you had to specify a search by name using the -name option. You could also have searched for files using many other criteria, such as modification date or owner. To have find search for files whose names match XF86Config, you’d have to use a wildcard:
$ find / -name ’*XF86Config*’