locate

On most Linux systems, the updatedb command runs once per day to gather the names of files throughout your Linux system and stores them in a local database. You can then run the locate command to search this database to find the location of named files stored within it.

Like anything, there are pros and cons to this approach...

Advantage	Disadvantage
The locate command finds files much faster than alternative methods because it searches a database instead of having to search the whole filesystem in live time	The locate command cannot find any files added to the system since the last time the database was updated via updatedb
	Not every file in your filesystem is stored in the database - see below

The contents of the /etc/updatedb.conf file limit which filenames are collected by excluding specific mount types, filesystem types, file types, and mount points. For instance, filenames are excluded from remotely mounted filesystems like CIFS and NFS, as well as locally mounted CDs or DVDs in the iso9660 format. Additionally, paths containing temporary files in /tmp and spool files in /var/spool/cups are pruned.

You have the flexibility to add or remove items from the locate database pruning list to customise it according to your requirements. For instance, in RHEL 8, the updatedb.conf file includes the following:

PRUNE_BIND_MOUNTS = "yes"
PRUNEFS = "9p afs anon_inodefs auto autofs bdev binfmt_misc cgroupcifs coda configfs cpuset debugfs devpts ecryptfs exofs fuse fuse.sshfs fusectl gfs gfs2 gpfs hugetlbfs inotifyfs iso9660 jffs2lustre mqueue ncpfs nfs nfs4 nfsd pipefs proc ramfs rootfs rpc_pipefs securityfs selinuxfs sfs sockfs sysfs tmpfs ubifs udf usbfsceph fuse.ceph"
PRUNENAMES = ".git .hg .svn .bzr .arch-ids {arch} CVS"
PRUNEPATHS = "/afs /media /mnt /net /sfs /tmp /udev /var/cache/ccache /var/lib/yum/yumdb /var/lib/dnf/yumdb /var/spool/cups /var/spool/squid /var/tmp /var/lib/ceph"

As a regular user, you can't see any files from the locate database that you can't see in the filesystem normally. For example, if you can't type ls to view files in the /root directory, you can't locate files stored in that directory either.

Using locate

When you search for a string, the string can appear anywhere in a file’s path. For example, if you search for passwd, you could turn up:

• /etc/passwd

• /usr/bin/passwd

• /home/example/passwd/pwdfiles.txt

• ...and any number of other places

If you add files to your system after updatedb runs, you can’t locate those files until updatedb runs again. To get the database to contain all files up to the current moment, you can simply run updatedb from the shell, but this must be done with root privileges.

Here are some examples of using the locate command to search for files:

locate .bashrc

Running locate to find any files that contain the string ".bashrc" in their name

When run as a regular user, locate only finds .bashrc in /etc/skel and the user’s own home directory. However, when run as root, the same command locates .bashrc files in everyone’s home directory.

Using locate -i, filenames are found regardless of case sensitivity.