Sed Streamline - Linux Text Crafting Essentials

Tue, 30 Dec 2025 00:00:00 +0000

Sed Streamline - Linux Text Crafting Essentials

GNU sed 4.9 (stable as of 2025-12-30). A stream editor for filtering and transforming text.

Core Syntax

The fundamental operation in sed is substitution. This block demonstrates basic text replacement.

# Example file content:
# line 1: This is a test.
# line 2: Another test line.
# line 3: Test complete.
# Basic substitution: 's/regexp/replacement/flags'
echo "This is a test." | sed 's/test/example/' # Replaces 'test' with 'example' on the first match per line.
# Output: This is a example.
# Global substitution (g flag): replaces all occurrences on a line.
echo "test test test" | sed 's/test/ok/g' # Replaces all 'test' with 'ok'.
# Output: ok ok ok
# Case-insensitive substitution (I flag - GNU sed extension).
echo "This Is A Test." | sed 's/test/success/I' # Replaces 'Test' with 'success', ignoring case.
# Output: This Is A success.

Essential Patterns

sed excels at filtering and deleting lines based on patterns or line numbers.

Pattern Power: Regex Fast-Track - JavaScript & Python Essentials

Sat, 27 Dec 2025 00:00:00 +0000

Pattern Power: Regex Fast-Track

Regular Expressions (Regex) for text pattern matching. Current versions: Python 3.12, JavaScript (ECMAScript 2024/ES15).

Core Syntax

Regex literals (JS) or compiled patterns (Python) define the search pattern. Flags modify behavior.

// JavaScript: Regex literal (preferred for static patterns)
const reLiteral = /abc/i; // Matches "abc" case-insensitively
// JavaScript: RegExp constructor (for dynamic patterns from strings)
const patternString = "xyz";
const reConstructor = new RegExp(patternString, 'g'); // Matches "xyz" globally
// Test method returns boolean
console.log(reLiteral.test("ABC")); // true
console.log(reConstructor.test("0xyz1xyz2")); // true

import re
# Python: Compile a regex pattern (preferred for repeated use)
pattern_compiled = re.compile(r"abc", re.IGNORECASE) # Matches "abc" case-insensitively
# Python: Direct function call (for one-off uses)
match_obj = re.search(r"xyz", "0xyz1xyz2", re.M) # Searches for "xyz" in the string
# Match object evaluates to True if a match is found
print(bool(pattern_compiled.search("ABC"))) # True
print(bool(match_obj)) # True

Essential Patterns

Character classes simplify matching common types of characters. Quantifiers specify how many times a character or group must appear.

Text Processing on AI VOID

Sed Streamline - Linux Text Crafting Essentials

Sed Streamline - Linux Text Crafting Essentials

Core Syntax

Essential Patterns

Pattern Power: Regex Fast-Track - JavaScript & Python Essentials

Pattern Power: Regex Fast-Track

Core Syntax

Essential Patterns