whatis

Overview

The whatis command displays one-line manual page descriptions. It searches the whatis database for complete words and shows brief descriptions of system commands.

Syntax

whatis [options] keyword...

Common Options

Option Description
-d Debug mode
-v Verbose output
-r Regex search
-w Wildcard search
-s sections Search sections
-l Long output
-M path Set manual path
-L locale Set locale
--regex Use regex
--wildcard Use wildcards
--long Long format

Manual Sections

Section Content
1 User commands
2 System calls
3 Library functions
4 Special files
5 File formats
6 Games
7 Miscellaneous
8 System administration
9 Kernel routines

Key Use Cases

  1. Quick reference
  2. Command verification
  3. Brief descriptions
  4. Command learning
  5. Documentation check

Examples with Explanations

Example 1: Basic Usage

whatis ls

Show ls command description

Example 2: Multiple Commands

whatis cp mv rm

Show multiple descriptions

Common Usage Patterns

  1. Single command:

    whatis command

  2. Section search:

    whatis -s 1 command

  3. Regex search:

    whatis -r pattern

Search Tips

  1. Use exact names
  2. Try wildcards
  3. Check sections
  4. Multiple keywords
  5. Verify results

Additional Resources

Best Practices

  1. Update database
  2. Verify commands
  3. Check sections
  4. Document findings
  5. Cross-reference

Output Format

  1. Command name
  2. Section number
  3. Brief description
  4. Multiple matches
  5. Error messages

Troubleshooting

  1. No matches
  2. Database issues
  3. Wrong section
  4. Locale problems
  5. Path configuration