Glob Pattern Mastery — Precise File Targeting

Core 6 min +25 XP

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THE ANALOGY

Regular expressions for file paths. Just as regex lets you match strings with precision, glob patterns let you target files with precision — not just by name, but by location, extension, depth, and exclusion.

⚠️ EXAM TRAP — The Wrong Answer People Choose

The difference between * and ** in globs. A single * matches within one directory level. Double ** matches across any number of directory levels. 'src/*.ts' matches only TypeScript files directly in src/. 'src/**/*.ts' matches TypeScript files in src/ and all subdirectories.

KEY POINTS

1 * matches any characters within a single directory level — does not cross directory boundaries.

2 ** matches across any number of directory levels — the 'recursive' wildcard.

3 ? matches exactly one character.

4 ! at the start of a pattern means exclusion — matches everything EXCEPT this pattern.

5 Patterns are evaluated relative to the project root — use ./ prefix if needed for clarity.

Glob Pattern Reference

*           Matches any characters within ONE directory level
**          Matches across any number of directory levels
?           Matches exactly ONE character
[abc]       Matches one character from the set (a, b, or c)
{a,b}       Matches either pattern a or pattern b
!pattern    Exclusion — matches everything except this

Pattern Examples

# All TypeScript files in src/ only (not subdirectories)
"src/*.ts"

# All TypeScript files in src/ AND all subdirectories
"src/**/*.ts"

# All TypeScript files anywhere in project
"**/*.ts"

# All TypeScript files except test files
"src/**/*.ts"
"!src/**/*.test.ts"
"!src/**/*.spec.ts"

# All files directly in root (no subdirectories)
"./*.json"

# All index.ts files anywhere
"**/index.ts"

# Files with multiple extensions
"**/*.{ts,tsx,js,jsx}"

# Specific directory names at any level
"**/components/**/*.tsx"

# Files in __tests__ directories
"**/__tests__/**"

The Common Mistakes

# ❌ Wrong: only matches src/auth.ts — not src/api/auth.ts
"src/*.ts"

# ✅ Right: matches TypeScript files at any depth in src/
"src/**/*.ts"

# ❌ Wrong: matches ALL TypeScript files — probably too broad
"**/*.ts"

# ✅ Right: matches only source TypeScript, excluding tests and config
"src/**/*.ts"
"!src/**/*.test.ts"
"!src/**/*.spec.ts"
"!**/*.config.ts"

Answers to the Teach-Back Challenge

# 1. TypeScript files in src/ and subdirectories, NOT test files
"src/**/*.ts"
"src/**/*.tsx"
"!src/**/*.test.ts"
"!src/**/*.test.tsx"
"!src/**/*.spec.ts"

# 2. All SQL files anywhere
"**/*.sql"

# 3. All files directly in root (not subdirectories)
"./*"
# Or more specific:
"./*.json"
"./*.ts"

# 4. All index.ts files anywhere
"**/index.ts"

Key Takeaways

* = one directory level, ** = across all levels
! prefix for exclusion — essential for precise targeting
{a,b} for multiple extensions in one pattern
Test patterns with find command before committing
More specific patterns are almost always better than broad ones