About rlocate

        rlocate for Linux (2.6 Kernel)
        Released January 27, 2005
        Copyright (c) 2004,2005 Rasto Levrinc
        Based on slocate by Kevin Lindsay

rlocate is an implementation of the ``locate'' command that is always up-to-date. The database that the original locate uses is usually updated only once a day, so newer files cannot be located right away. The behavior of rlocate is the same as slocate, but it also maintains a diff database that gets updated whenever a new file is created. This is accomplished with rlocate kernel module and daemon. The rlocate kernel module can be compiled only with Linux 2.6 kernels.

If you are interested how it is done internally, here is how:

rlocate.ko is kernel module, that can be compiled and insmoded to the kernel. It has hooks for link, mkdir, mknod, open, rename and symlink system calls with help of lsm. It stores filenames to the internal list. Since all the file names have slash in the beginning it is replaced either with 'a' or 'm' depending on if a file or directory is added or directory is moved in the filesystem. Reason for that is, that directories that are renamed must be traversed in the rlocate daemon later.

The module communicates with rlocate daemon with help of /dev/rlocate device file. It writes all the file names with one file name per line to this device file.

rlocated is a daemon that reads /dev/rlocate device file and writes the paths without leading '/' to the rlocate diff database. It does that every 2 seconds. If a directory was moved, it will be traversed and entries in the directory and its subdirectories are written to the diff database.

The locate command searches in rlocate database, which is the same as original slocate database, diff database and temporal diff database. The diff databases contain file names were added to the filesystem.

During the search also the file names are checked if they are accessible. If a file name was removed, it is not accessible, so it will be not shown.

The diff database is copied to temporal diff database and is emptied in the beginning of the updatedb and the temporal diff database is removed after updatedb is done. The reason for that is, so that also during updatedb is running, which can take several minutes, the locate command returns the correct results.

updatedb should be run daily e.g. as a cron job same as with slocate. Otherwise the searches would become slower with time.

updatedb runs in two modes - fast update or full update. Fast update takes 2 to 10 seconds to complete. Full update takes several minutes. The drawback of fast update is, that the database becomes more or less larger each day, since it contains also file names, that were removed. Fast update is run automatically every time, except the first time and every tenth time updatedb is started.

Kernel configuration

Before you start, check that you have Linux kernel version 2.6, and ``Enable different security models'' is set to yes.

At the moment the stacking with other security modules is not implemented, so it is not possible to load other security modules with rlocate.

The ``Default Linux Capabilities'' must be either disabled or set to 'M' in your kernel configuration in ``Security options'' section. Capability module cannot be loaded at the same time as rlocate. Disable also NSA SELinux.

You can add selinux=0 in your boot loader config file. In grub that would be - /boot/grub/menu.lst.

If you don't, you get this error later by insmoding the module:

        FATAL: Error inserting rlocate
        (/lib/modules/2.6.9-1.667/misc/rlocate.ko): Invalid argument

Capabilities and SELinux are usually enabled by default in newest Debian, RedHat, SuSE etc. distributions and you would have to recompile the kernel. This problem will be probably solved in the future, when better stacking of security modules is possible.

Installation from tarball

First unpack the archive rlocate-x.x.x.tar.gz.

Enter the rlocate-x.x.x directory and type:

        su -c "make install"

After that, load the rlocate kernel module as root, for example with:

        modprobe rlocate

Or you can use some mechanism of your distribution to load the module at boot time.

You need to start rlocated daemon as root too. You can use some of the init scripts in contrib directory for your distribution.

        /etc/init.d/rlocate start



as root or wait for cron job and you have locate that is always up-to-date.

It will hopefully compile and it works. If it doesn't you can either email me <e9526925@stud3.tuwien.ac.at> or make a patch and send it to me.


Enter the rlocate-x.x.x directory and type:

        su -c "make uninstall"

Installing debian packages

There are two debian packages,

provides the source for the kernel modules.

You can install it using the make-kpkg(1) command provided by the kernel-package Debian package. This will produce a corresponding rlocate-module package for the Debian kernel-image package that you are using. This is ``the Debian way''. See the ``modules_image'' section of the make-kpkg(1) man page. Notice that you have to be root to build the rlocate-module.

You need to have kernel-image-2.6.x installed for following.

First install source package as root

dpkg -i rlocate-source_x.x.x_all.deb

This will install rlocate.tar.gz to the /usr/src directory. Untar it

tar xvzpf rlocate.tar.gz

Change to /usr/src/linux-2.6.x directory and make modules image

make-kpkg modules_image

Install rlocate module

dpkg -i /usr/src/rlocate-module-... i386.deb

provides user-space applications for searching the file names in the database.

You can install it with following command

dpkg -i rlocate_x.x.x_i386.deb

After that, you need to create the database and you are done.


Setting up rlocate manually

1. If the make install does not work, a manual setup will have to be done. The first thing to do is copy the rlocate binary to a directory in your path. Usually the directory:


will suffice.

2. Next you must create a group called:

You can do this by either editing the /etc/group file manually or use a group add utility. The following is supported by Linux:

        groupadd rlocate

3. Once the group has been created, you must now change the ownership and permissions of the rlocate and rlocated binaries. To do this execute the following commands.

        chown root:rlocate /usr/local/bin/rlocate
        chmod 2755 /usr/local/bin/rlocate
        chown root:root /usr/local/sbin/rlocated 
        chmod 0755 /usr/local/bin/rlocated

4. To make rlocate more convenient to use, you can symlink 'rlocate' to 'locate'.

Move the old version of locate to something else if it exists.

        ln -s /usr/local/bin/rlocate /usr/local/bin/locate

5. To make updating the database more convenient, you may link 'rlocate' to 'updatedb'. This way, just running 'updatedb' will start to index your entire drive.

        ln -s /usr/local/bin/rlocate /usr/local/bin/updatedb

6. Then you have to make sure this path exits:


You can do this by executing this command:

        mkdir -p /usr/local/var/rlocate

Now just give it the right ownership:

        chown root:rlocate /usr/local/var/rlocate

7. Then you have to load rlocate.ko module from rlocate-module directory. You can copy it to:


directory and make sure, that module is loaded at boot time. How it is done depends on your linux distribution. Change 2.6.x to your kernel version. ``Enable different security models'' must be set and ``Default Linux Capabilities'' must be unset or set to ``M'' in your kernel configuration in ``Security options'' section. Disable also NSA SELinux. You can add selinux=0 in your boot loader config file. In grub that would be - /boot/grub/menu.lst.

8. Now you need init script to start rlocated daemon from rlocate-daemon directory. Some example init scripts are in contrib directory. You should copy it to /etc/init.d directory or something like that.

Copy the rlocated binary for example in:



9. Create a /dev/rlocate device file if you are not using udev or devfs. You will have to look in kernel log file after loading the rlocate module for major number. You can do it with this command:

        mknod /dev/rlocate c 254 0

where 254 is major number, that can be different on your computer.

Creating the database

When creating the database, there are a few options that you may use to customize which files get indexed and how. The database will be stored in /var/lib/rlocate/. The two main options are:

        -u       - Indexes every file on your system.
        -U <dir> - Indexes every file in the directory <dir>.

Below are some examples of different types of indexing options:

Create an index of every file in every directory on your system.

        rlocate -u

Create an index of every file in the specified directory <dir>.

        rlocate -U <dir>

Create an index of every file excluding the specified files/directories, /proc /dev and /tmp

        rlocate -e "/proc,/dev/,/tmp" -u

Create an index of every file excluding files on NFS and iso9660 type filesystems.

        rlocate -f "NFS,iso9660" -u

If you symlinked /usr/local/bin/rlocate to /usr/local/bin/updatedb, then executing the updatedb command will automatically index the root filesystem starting at '/'. This will also cause the file '/etc/updatedb.conf' to be parsed. This file is in the same format as the original updatedb.sh configuration file.

rlocate options

     -u                 - Create rlocate database starting at path /.
     -U <dir>           - Create rlocate database starting at path <dir>.
     -e <dir1,dir2,...> - Exclude directories from rlocate database.
     -f <fstype1,...>   - Exclude files on specified filesystem types from 
                          the rlocate database.
     -c                 - Force rlocate to parse '/etc/updatedb.conf' when
                          updating the database.
     -q                 - Quite mode.  Error messages are suppressed.
     -n <num>           - Limit the amount of results shown to <num>.
     -i                 - Does a case insensitive search.
     -r <regexp>
     --regexp=<regexp>  - Search the database using a basic POSIX regular
     -o <file>
     --output=<file>    - Specifies the database to create.
     -d <path>
     --database=path    - Specifies path of database to search in.
     --initdiffdb       - Initializes the diff database if user database is
                          created. If default database is created --initdiffdb 
                          is implied.
     --fast-update      - Force fast update of the default database.
     --full-update      - Force full update of the default database.
     --help             - Display this help.
     --verbose          - Verbose mode. Display files when creating database.
     --version          - Display version.

rlocate-checkpoint options

        Usage: /usr/local/bin/rlocate-checkpoint [OPTION]
        With no OPTION: show file names, that were added to the filesystem
                        since the last updatedb or after checkpoint, if 
                        a checkpoint was created with --create option.
         -c --create          - Create a check point.
         -d --database=<path> - Specifies the path of databases, delimited 
                                with ':', to search in.
         -v --verbose         - Verbose mode.
         -h --help            - Display this help and exit.
         -V --version         - Display version.


rlocate will work only on Linux with version 2.6.


        Peter Robinson for lsm implementation
        Kevin Lindsay for original slocate
        Sven Luther for debian code from his unicorn package.
        Anton Eartl for the idea and suggestions.

Author and bugs

Author: Rasto Levrinc

Bug Reports: e9526925@stud3.tuwien.ac.at

HTTP: http://www.sourceforge.net/projects/rlocate/

Bugs: Stacking with other security modules is not implemented yet.


My homepage (http://stud3.tuwien.ac.at/~e9526925/)

Doodle (http://gnunet.org/doodle/) is a tool to quickly search the documents on a computer. It uses different approach for keeping its database up-to-date.

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