head

Overview

The head command outputs the first part of files. By default, it prints the first 10 lines of each file to standard output.

Syntax

head [options] [file...]

Common Options

Option Description
-n num Print first num lines
-c num Print first num bytes
-q Never print headers
-v Always print headers
--bytes=[-]num Print first num bytes
--lines=[-]num Print first num lines
-z Line delimiter is NUL
--help Display help message
--version Output version information

Key Use Cases

  1. View file beginning
  2. Check file headers
  3. Monitor log files
  4. Quick file inspection
  5. Data sampling

Examples with Explanations

Example 1: Default Usage

head file.txt

Show first 10 lines

Example 2: Specific Lines

head -n 5 file.txt

Show first 5 lines

Example 3: Multiple Files

head -n 3 file1 file2

Show first 3 lines of each file

Understanding Output

  • Default: 10 lines
  • With multiple files:
    • ==> filename <== headers
  • Error messages for:
    • File not found
    • Permission denied
    • Invalid number argument

Common Usage Patterns

  1. View file start:

    head -n 20 file

  2. Check byte count:

    head -c 1000 file

  3. Monitor new log entries:

    head -f logfile

Performance Analysis

  • Fast operation
  • Memory efficient
  • Handles large files well
  • Stream processing
  • Multiple file overhead

Additional Resources

Use Cases

  1. Log file inspection
  2. File format verification
  3. Quick content preview
  4. Data sampling
  5. Script debugging