Overview

awk is a pattern scanning and processing language designed for structured text.

Syntax

awk [options] 'pattern { action }' file...

Arguments

• pattern: Condition for matching.
• action: Command to run for each match.

Options Table

Examples

awk -F":" '{print $1}' /etc/passwd
awk '{sum += $5} END {print sum}' access.log

Real-world Usage

Extract unique IPs from logs and calculate request volume.

Common Mistakes

• Forgetting to set the field separator.
• Using awk where cut or grep is sufficient.

Performance Notes

awk is fast on large streams, but avoid complex regex when possible.

Security Considerations

Do not execute untrusted awk scripts downloaded from unknown sources.

Related Commands

grep, sed, cut

Practice Exercises

1. Print the first and fifth columns from a CSV file.
2. Count total bytes from a log file with a size column.