How to update Linux "locate" cache

The command is:

sudo updatedb

See man updatedb for more details.

On OSX this is: sudo /usr/libexec/locate.updatedb

Which can be linked with: sudo ln -s /usr/libexec/locate.updatedb /usr/local/bin/updatedb

Seems silly to have to make a symbolic link for a standard unix command, but there it is.

While the answer:

sudo updatedb

is technically correct, it is almost never a good idea to run updatedb on a command line by itself, if there is also a cron job installed. Depending on the Unix flavor the cronjob contains locking provisions and any amount of configuration which is not covered by the standalone updatedb command.

If the locate database needs to be updated frequently, it is definitely worth the effort to determine the proper cron job for a specific host and run it manually.

Depending on the administrator, the cronjob for updatedb may be hidden in various locations. So a simple brute-force attempt to find the cron job would be:

( sudo crontab -l > /tmp/crontab.root;
  ( echo /tmp/crontab.root; ls -1d /etc/*cron* /etc/*cron*/* ) \
  | tr '\n' '\0' \
  | xargs -0 -r -e grep -nH -e updatedb;
  rm -f /tmp/crontab.root
) 2>/dev/null

which shows the following result on one of my Ubuntu systems:

/etc/cron.daily/mlocate:5:[ -x /usr/bin/updatedb.mlocate ] || exit 0
/etc/cron.daily/mlocate:21:flock --nonblock /run/mlocate.daily.lock $IONICE /usr/bin/updatedb.mlocate

The correct command to update the locate database in this case is therefore

sudo /etc/cron.daily/mlocate

A more systematic approach is to determine the package which provides locate and updatedb.

E.g., on an OS with apt/dpkg packaging you can find which flavor of locate is installed with:

dpkg -S locate | grep /bin/

In my case it is:

mlocate: /usr/bin/updatedb.mlocate

To see, which cron job if any is responsible, run:

dpkg -L mlocate | grep cron

Which in my case shows:

/etc/cron.daily
/etc/cron.daily/mlocate

To update the database, run the cron job as root:

sudo /etc/cron.daily/mlocate

If there is no cronjob, and updatedb by itself does not work, try finding your installed flavor with:

dpkg -L mlocate | grep /bin/

which returns:

/usr/bin/mlocate
/usr/bin/updatedb.mlocate

NB: If you downvote this answer, be so nice and let me know why the hobbyist answer is considered better.