Locate & UpdateDB File Search

Install mlocate

# Ubuntu/Debian
sudo apt install mlocate

# RHEL/CentOS
sudo yum install mlocate

# macOS
brew install mlocate

Basic locate usage

# Find files
locate filename

# Case insensitive
locate -i filename

# Count results
locate -c filename

# Show only existing files
locate -e filename

Update database

# Manual update
sudo updatedb

# Update specific paths
sudo updatedb --prunepaths='/tmp /var/tmp'

Search patterns

# Exact filename
locate -b '\filename.txt'

# Files ending with .conf
locate '*.conf'

# Files in specific directory
locate '/etc/*.conf'

# Multiple patterns (OR)
locate -i  'readme' | grep -i 'docker'

Limit results

# First 10 results
locate -l 10 filename

# Stop after N matches
locate -n 10 filename

Regular expressions

# Regex search
locate -r '.*/config.*\.xml$'

# Case insensitive regex
locate -ri 'readme'

Statistics

# Show database statistics
locate -S

Output example:

Database /var/lib/mlocate/mlocate.db:
    58,102 directories
    682,394 files
    35,901,384 bytes in file names
    16,306,432 bytes used to store database

Database location

# Default database
/var/lib/mlocate/mlocate.db

# Custom database
locate -d /path/to/custom.db pattern

Create custom database

# Create database for specific directory
updatedb -l 0 -o ~/myfiles.db -U /path/to/dir

# Use custom database
locate -d ~/myfiles.db filename

Configuration

Edit /etc/updatedb.conf:

PRUNE_BIND_MOUNTS="yes"  
PRUNENAMES=".git .svn .hg"
PRUNEPATHS="/tmp /var/spool /media"
PRUNEFS="NFS nfs nfs4 rpc_pipefs afs binfmt_misc"

Exclude directories

# Skip specific paths
PRUNEPATHS="/tmp /var/tmp /mnt /media"

Auto-update schedule

Check cron:

# Ubuntu/Debian
cat /etc/cron.daily/mlocate

# RHEL/CentOS
cat /etc/cron.daily/mlocate.cron

Find recently modified files

# Combine locate with find
locate filename | xargs ls -lt | head

Common use cases

Find config files

locate -i '*.conf' | grep nginx

Find log files

locate -r '\.log$' | grep -v '/var/log'

Find executables

locate -b '\command' | grep bin

Find documentation

locate -i readme | grep -i docker

Performance comparison

# locate (very fast, uses database)
time locate filename

# find (slow, searches filesystem)
time find / -name filename 2>/dev/null

Locate vs Find

locate:
+ Much faster (uses database)
+ Lower system load
- Requires updatedb
- May show deleted files
- Database must be current

find:
+ Real-time search
+ More search options
+ Accurate results
- Slower
- Higher I/O

Verify file exists

# locate might show deleted files
locate filename | while read file; do
    [ -e "$file" ] && echo "$file"
done

# Or use -e flag
locate -e filename

Search in specific directory

# Pipe to grep
locate filename | grep '^/home/'

# Or with regex
locate -r '^/home/.*filename'

Count files by type

#!/bin/bash
for ext in txt pdf doc jpg png; do
    count=$(locate "*.$ext" | wc -l)
    echo "$ext: $count"
done

Find duplicates by name

locate filename | \
  rev | cut -d'/' -f1 | rev | \
  sort | uniq -d

Exclude patterns

# Find .conf but exclude /etc
locate -i '*.conf' | grep -v '^/etc/'

Interactive search

#!/bin/bash
read -p "Search for: " query
results=$(locate -i "$query")

if [ -z "$results" ]; then
    echo "No results found"
else
    echo "$results" | nl
    read -p "Open file number: " num
    file=$(echo "$results" | sed -n "${num}p")
    xdg-open "$file"
fi

Find and open

# Find and edit
locate vimrc | head -1 | xargs vim

# Find and view
locate readme.md | fzf | xargs cat

Troubleshooting

Database not found

# Create database
sudo updatedb

Permission denied

# Some files require root
sudo locate filename

Old results

# Update database
sudo updatedb

# Force full update
sudo updatedb -U /

Automation

Daily update script

#!/bin/bash
# /etc/cron.daily/updatedb-custom

# Update main database
/usr/bin/updatedb

# Update custom database
/usr/bin/updatedb -l 0 -o /home/user/mydb.db -U /home/user

Monitor new files

#!/bin/bash
before=$(mktemp)
after=$(mktemp)

locate '*.log' | sort > "$before"
sleep 60
sudo updatedb
locate '*.log' | sort > "$after"

echo "New log files:"
comm -13 "$before" "$after"

rm "$before" "$after"

mlocate vs plocate

# plocate (faster alternative)
sudo apt install plocate

# Same syntax
plocate filename

Best practices

# 1. Update database regularly
sudo updatedb

# 2. Use -e for existing files
locate -e filename

# 3. Combine with other tools
locate '*.log' | xargs wc -l

# 4. Use basename search
locate -b '\exact-name'

# 5. Create custom databases for large dirs
updatedb -o ~/projects.db -U ~/Projects

Alternatives

# fd (modern alternative)
fd filename

# ripgrep (content search)
rg "pattern"

# fzf (fuzzy finder)
find . | fzf

# Everything (Windows)
# Similar concept to locate