updatedb Command Linux: Complete Guide to Update Locate Database

The updatedb command is a crucial system utility in Linux that updates the database used by the locate command for fast file searching. This powerful tool indexes file and directory names across your entire filesystem, creating a searchable database that dramatically speeds up file location operations.

What is updatedb Command?

The updatedb command is part of the GNU findutils package and serves as the backend database updater for the locate command. It scans your entire filesystem and creates an indexed database of all files and directories, which is then stored in /var/lib/mlocate/mlocate.db or /var/lib/locatedb depending on your system configuration.

Basic Syntax

The basic syntax of the updatedb command is straightforward:

updatedb [OPTIONS]

In most cases, you’ll run updatedb without any options:

sudo updatedb

Why Use updatedb?

• Speed: Makes file searching extremely fast through the locate command
• Efficiency: Pre-indexed database eliminates the need for real-time filesystem scanning
• System Integration: Automatically scheduled via cron jobs on most Linux distributions
• Resource Management: Runs during low-activity periods to minimize system impact

Common Options and Parameters

–localpaths

Specifies which directories to include in the database:

sudo updatedb --localpaths="/home /usr /opt"

–prunepaths

Excludes specific directories from indexing:

sudo updatedb --prunepaths="/tmp /var/tmp /proc"

–output

Specifies a custom output file for the database:

sudo updatedb --output=/home/user/custom.db

–require-visibility

Ensures only files visible to the user running locate are included:

sudo updatedb --require-visibility=1

–debug-pruning

Shows which directories are being pruned during the scan:

sudo updatedb --debug-pruning

Practical Examples

Example 1: Basic Database Update

The most common usage is running updatedb with sudo privileges:

$ sudo updatedb

Output:

# No output typically displayed, runs silently
# Database updated in background

Example 2: Updating with Verbose Output

To see what updatedb is doing, you can redirect stderr:

$ sudo updatedb 2>&1 | head -10

Output:

updatedb: can't stat `/proc/1/task/1/fd/4': Permission denied (os error 13)
updatedb: can't stat `/proc/1/task/1/fd/5': Permission denied (os error 13)
Scanning /home...
Scanning /usr...
Scanning /var...

Example 3: Custom Database Location

Create a personal locate database:

$ updatedb --localpaths="/home/$USER" --output="$HOME/personal.db"

Usage with custom database:

$ locate -d "$HOME/personal.db" "*.pdf"

Example 4: Excluding Directories

Update database while excluding temporary and cache directories:

$ sudo updatedb --prunepaths="/tmp /var/tmp /var/cache /home/*/.cache"

Configuration File

The updatedb command reads its configuration from /etc/updatedb.conf. Here’s a typical configuration:

# /etc/updatedb.conf
PRUNE_BIND_MOUNTS="yes"
PRUNENAMES=".git .bzr .hg .svn"
PRUNEPATHS="/tmp /var/spool /media /var/lib/os-prober /var/lib/ceph"
PRUNEFS="NFS nfs nfs4 rpc_pipefs afs binfmt_misc proc sysfs usbfs autofs"

Configuration Parameters Explained:

• PRUNE_BIND_MOUNTS: Skip bind mounts when set to “yes”
• PRUNENAMES: Directory names to skip entirely
• PRUNEPATHS: Specific paths to exclude from indexing
• PRUNEFS: Filesystem types to skip

Automatic Scheduling

Most Linux distributions automatically schedule updatedb to run daily. Check your cron configuration:

$ cat /etc/cron.daily/mlocate

Typical cron job content:

#!/bin/bash
/usr/bin/updatedb

To check if it’s scheduled in systemd:

$ systemctl list-timers | grep updatedb

Performance Considerations

System Impact

Running updatedb can be I/O intensive. Monitor system load:

$ sudo nice -n 19 ionice -c 3 updatedb

This runs updatedb with:

• nice -n 19: Lowest CPU priority
• ionice -c 3: Idle I/O scheduling class

Checking Database Status

View current database information:

$ locate -S

Output:

Database /var/lib/mlocate/mlocate.db:
    21,132 directories
    136,530 files
    7,823,933 bytes used to store database

Troubleshooting Common Issues

Permission Denied Errors

If you encounter permission errors:

$ sudo updatedb --debug-pruning 2>&1 | grep "Permission denied" | head -5

These are typically normal for system directories that regular users shouldn’t access.

Database Not Found

If locate reports “database not found”:

$ sudo updatedb
$ locate --database=/var/lib/mlocate/mlocate.db test

Slow Performance

For large filesystems, consider excluding unnecessary directories:

$ sudo updatedb --prunepaths="/mnt /media /backup"

Security Considerations

File Visibility

The locate database may contain filenames that should be private. Modern implementations use the --require-visibility option by default, ensuring users can only find files they have permission to access.

Sensitive Directories

Always exclude sensitive directories from indexing:

PRUNEPATHS="/home/*/.ssh /home/*/.gnupg /root"

Integration with Other Commands

Using with locate

After updating the database, use locate to find files:

$ sudo updatedb
$ locate "*.conf" | head -5

Output:

/etc/systemd/system.conf
/etc/systemd/user.conf
/etc/fonts/fonts.conf
/etc/host.conf
/etc/nsswitch.conf

Scripting with updatedb

Create a script for regular maintenance:

#!/bin/bash
# Update locate database with custom settings
echo "Updating locate database..."
sudo updatedb --prunepaths="/tmp /var/tmp /media /mnt" \
              --prunenames=".git .svn node_modules"
echo "Database update completed"
locate -S

Alternative Implementations

mlocate vs slocate vs GNU locate

• mlocate: Most common, security-aware implementation
• slocate: Secure locate, predecessor to mlocate
• GNU locate: Original implementation from findutils

Check your implementation:

$ updatedb --version

Best Practices

1. Regular Updates: Keep the database current with daily automatic updates
2. Exclude Temporary Files: Configure appropriate PRUNEPATHS to avoid indexing temporary data
3. Monitor Performance: Use nice and ionice for background execution
4. Security Awareness: Ensure sensitive directories are excluded from indexing
5. Custom Databases: Create specialized databases for specific use cases

Conclusion

The updatedb command is an essential tool for maintaining an efficient file search system in Linux. By understanding its options, configuration, and best practices, you can optimize your system’s file indexing to balance search speed with system performance and security. Regular database updates ensure that the locate command remains a powerful tool for quick file discovery across your Linux filesystem.

Remember to configure updatedb appropriately for your system’s needs, exclude unnecessary directories to improve performance, and maintain security by preventing indexing of sensitive locations. With proper setup and maintenance, updatedb provides the foundation for lightning-fast file searches across even the largest Linux filesystems.