du

Overview

The du (disk usage) command estimates file space usage. It summarizes disk usage of each file and directory recursively.

Syntax

du [options] [file...]

Common Options

Option Description
-h Human readable sizes
-s Display only total
-c Show grand total
-a Show all files
-b Show size in bytes
-k Show size in kilobytes
-m Show size in megabytes
--max-depth=N Show subdirs only to depth N
--apparent-size Print apparent sizes
--time Show last modification time
-x Stay on one filesystem

Key Use Cases

  1. Storage analysis
  2. Directory size checking
  3. Disk cleanup
  4. Space monitoring
  5. Quota management

Examples with Explanations

Example 1: Directory Summary

du -sh *

Show total size of each item in current directory

Example 2: Depth Limited

du --max-depth=2 /home

Show usage up to 2 levels deep

Example 3: Sort by Size

du -h | sort -hr

Show sorted usage by size

Understanding Output

Format:

Size    Path
4.0K    ./file1
8.0K    ./dir1
12K     .

Common Usage Patterns

  1. Find large directories:

    du -h --max-depth=1 | sort -hr

  2. Check specific directory:

    du -sh /var/log

  3. Show all files:

    du -ah

Performance Analysis

  • I/O intensive operation
  • Directory traversal impact
  • Large directory handling
  • Memory usage considerations
  • Network filesystem impact

Additional Resources

Best Practices

  1. Use human readable format
  2. Limit depth for large trees
  3. Consider filesystem boundaries
  4. Sort output when needed
  5. Regular monitoring

Common Issues

  1. Permission denied errors
  2. Network latency
  3. Hard link counting
  4. Sparse file handling
  5. Special filesystem types