There are two different facilities for finding files: find and
locate. find searches the actual files in their present state.
locate searches an index generated by the system every morning at
6:42 a.m. (this is a cron job, explained elsewhere in this book).
locate won’t find any files that were created after the index was
generated. However, because locate searches an index, it’s much
faster—like using the index of a book rather than looking through
the whole thing.
To compare the two ways of finding files, pretend you can’t remember
where the X configuration file XF86Config resides.
$ 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*’
Like most of the command line tools, find accepts wildcards as
arguments.
In general, find is a more powerful utility, and locate is faster
for everyday quick searches. The full range of possible searches
would take a long time to explain; for more details , type info
find, which will bring up the very thorough info pages on find and
locate.