Basics of sed and awk

🔍 Introduction

sed (Stream Editor) and awk (Text Processing Tool) are powerful command-line utilities for text manipulation in Linux. They are widely used for pattern searching, text replacement, and data extraction.

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Why Learn sed and awk?

Mastering these tools enables efficient text manipulation, automation of repetitive tasks, and advanced data processing in Linux environments.

🛠 sed - Stream Editor

sed is primarily used for modifying or filtering text in a stream or file.

🔹 Basic Syntax

sed [OPTIONS] 'COMMAND' file

✨ Common sed Commands

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💡 Print Specific Lines

sed -n '3p' file.txt  # Print only the 3rd line

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🗑 Delete Lines

sed '2d' file.txt  # Delete the 2nd line

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🔄 Find and Replace

sed 's/old/new/g' file.txt  # Replace 'old' with 'new' globally

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➕ Insert and Append Text

sed '3i\New line before line 3' file.txt  # Insert before line 3
sed '3a\New line after line 3' file.txt   # Append after line 3

📊 awk - Pattern Scanning & Processing

awk is used for pattern-based scanning, data extraction, and text transformation.

🔹 Basic Syntax

awk 'PATTERN { ACTION }' file

✨ Common awk Operations

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📌 Print Specific Columns

awk '{print $1, $3}' file.txt  # Print 1st and 3rd columns

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📊 Filter Lines Based on Condition

awk '$3 > 50 {print $0}' file.txt  # Print lines where 3rd column > 50

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🔄 Find and Replace

awk '{gsub(/old/, "new"); print}' file.txt  # Replace 'old' with 'new'

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🔢 Count Lines Matching a Pattern

awk '/pattern/ {count++} END {print count}' file.txt

⚖ Key Differences Between sed and awk

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Feature	sed	awk
Primary Use	Text substitution & filtering	Data extraction & processing
Syntax Complexity	Simple	More powerful & flexible
Supports Arithmetic	No	Yes
Works Line-by-Line	Yes	Yes, but also processes fields

🎯 Conclusion

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• ✅ Use sed for simple text replacements, deletions, and insertions.
• ✅ Use awk for more advanced text processing, such as column-based manipulations and calculations.

🚀 Mastering sed and awk can significantly enhance your Linux text processing skills!