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This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.


  • The locate *nix utility lets you find files by name, without going through your filesystem like with find
  • ...from an database, that is typically rebuilt every night, via a tool often called (updatedb)

  • of the (GNU, slocate, mlocate) set, you probably want mlocate
  • you probably have mlocate
  • locate will be symlinked to mlocate/slocate if you use them


GNU locate

(part of GNU findutils)

Build and index of readable files (verify) (when run as root, this typically means everything(verify))

slocate and mlocate

(s for secure, m for merging)

slocate stores file permissions and ownership as seen at index time, and slocate's locate command will filter out entries that the invoking user couldn't read.

mlocate extends slocate, in that its updatedb only rereads a directory contents if that directory's mtime changed, which on mostly-unchanging filesystems avoids stat()ing most entries/files on the filesystem, so it's done much faster and does many fewer syscalls / much less IO.



Hooks into the kernel (via a kernel module), in that it has a hook into syscalls like open, mkdir, mknod, link, rename, symlink.

Its Template:Inlincode searches both the database and kernel list, so you'll see new files within seconds of their creation.

See also:

Behaviour and configuration


Can be told not look in certain places.

Details vary slightly between implementations, but most support at least:

  • don't go under certain absolute paths
will not add its content, but still enter the directory name itself
avoid trailing slashes
  • don't index certain filesystem types

mlocate/slocate add stuff, including:

  • directory basename
e.g. .git .bzr .hg .svn, because their existance may be interesting but their filenames not so much

security notes

Ancient locate would let you see filenames that you couldn't find yourself.

slocate/mlocate hide filenames the calling user couldn't read, by also storing permissions and checking with that. (note that this is only really more secure if only the tools (and not the user) can read that database, which is why mlocate/slocate usually has a user account / group and are SUID/GUID)

Keep in mind that indexed permissions can be a day behind, so if your permissions were previously too lax, locate will still mention these files, until after the next index.

If you want to avoid that, you can make updatedb store a flag into the database that means "locate should stat() the parent directories to see if the calling user could list this(verify)". This comes at the cost of more IO on every locate.

some inspection

The database may be in one of various places, depending on which one you use.

Perhaps the simplest summary comes from

locate -S

Which in my case says something like:

Database /var/lib/mlocate/mlocate.db:
       552,900 directories
       5,639,641 files
       428,849,911 bytes in file names
       181,205,838 bytes used to store database

...yes, that's 5+ million files and I really need to clean up:P though the database is only ~170MB.

Listing all entries could be done like

sudo locate /

...but keep in mind that if the security flag mentioned above applies, it means access() calls for everything.