fsck

Overview

The fsck (File System Check) command checks and optionally repairs Linux filesystems. It’s a front-end for filesystem-specific checkers (fsck.fstype).

Syntax

fsck [options] [-t type] [filesystem...]

Common Options

Option Description
-A Check all filesystems
-C Display progress bar
-f Force check
-M Skip mounted
-N Don’t execute
-P Parallel check
-R Skip root filesystem
-T Don’t show title
-V Verbose
-y Assume yes

Exit Codes

Code Description
0 No errors
1 Filesystem fixed
2 System should be rebooted
4 Filesystem errors left
8 Operational error
16 Usage or syntax error
32 Fsck canceled
128 Shared library error

Key Use Cases

  1. Filesystem repair
  2. Error checking
  3. System maintenance
  4. Recovery operations
  5. Boot problems

Examples with Explanations

Example 1: Basic Check

fsck /dev/sdb1

Check specific device

Example 2: Force Check

fsck -f /dev/sdc1

Force check even if clean

Example 3: Auto-repair

fsck -y /dev/sdd1

Automatically fix errors

Common Usage Patterns

  1. Check all:

    fsck -A -V

  2. Dry run:

    fsck -N /dev/sdb1

  3. Progress bar:

    fsck -C /dev/sdc1

Security Considerations

  1. Root access
  2. Data integrity
  3. System stability
  4. Backup importance
  5. Mount status

Additional Resources

Best Practices

  1. Regular checks
  2. Unmount first
  3. Backup data
  4. Document errors
  5. Monitor logs

Error Types

  1. Inode errors
  2. Block errors
  3. Directory errors
  4. Superblock issues
  5. Journal problems

Troubleshooting

  1. Boot issues
  2. Mount failures
  3. Data corruption
  4. Performance problems
  5. System crashes