Search & Replace with Ripgrep

Intermediatev1.0.0

Use ripgrep for codebase-wide search and replace — previewing changes, piping to sed for replacement, using capture groups, and safely refactoring across large projects.

Content

Overview

Ripgrep excels at finding patterns, and paired with sed or other tools, enables safe codebase-wide refactoring. Preview changes before applying, use capture groups for smart replacements, and verify results.

Why This Matters

-Refactoring — rename functions, variables, and APIs across files
-Migration — update import paths, API endpoints, and config keys
-Cleanup — remove debug statements, fix typos, update patterns
-Safety — preview all changes before committing

How It Works

Step 1: Preview Matches

bash

# Find all matches first
rg "oldFunction" --type ts

# See context around matches
rg -C 2 "oldFunction" --type ts

# Count affected files
rg -l "oldFunction" --type ts | wc -l

# Preview replacement with --passthru
rg "oldFunction" -r "newFunction" --passthru --type ts

Step 2: Simple Replacement with sed

bash

# Replace in all matching files
rg -l "oldFunction" --type ts | xargs sed -i 's/oldFunction/newFunction/g'

# macOS (BSD sed requires backup extension)
rg -l "oldFunction" --type ts | xargs sed -i '' 's/oldFunction/newFunction/g'

# Safe replacement (create backups)
rg -l "oldFunction" --type ts | xargs sed -i.bak 's/oldFunction/newFunction/g'

# Multiple replacements
rg -l "oldAPI" --type ts | xargs sed -i \
  -e 's/oldAPI/newAPI/g' \
  -e 's/v1\/endpoint/v2\/endpoint/g'

Step 3: Regex Replacement with Capture Groups

bash

# Preview regex replacement (ripgrep -r flag)
rg "console\.(log|warn)\((.*)\)" -r "logger.$1($2)" --type ts

# Apply with sed (capture groups)
rg -l "console\.log" --type ts | xargs sed -i 's/console\.log(\(.*\))/logger.info\1/g'

# Rename CSS class prefix
rg -l "btn-primary" --type css | xargs sed -i 's/btn-primary/button-primary/g'

# Update import paths
rg -l "from '@/old-path/" --type ts | xargs sed -i "s|from '@/old-path/|from '@/new-path/|g"

Step 4: Safe Refactoring Workflow

bash

# 1. Create a branch
git checkout -b refactor/rename-api

# 2. Preview changes
rg "OldAPIClient" --type ts -C 1

# 3. Apply replacement
rg -l "OldAPIClient" --type ts | xargs sed -i 's/OldAPIClient/NewAPIClient/g'

# 4. Verify no missed references
rg "OldAPIClient" --type ts    # should return nothing

# 5. Check for broken references
rg "NewAPIClient" --type ts    # verify replacements look correct

# 6. Run tests
npm test

# 7. Review diff
git diff

# 8. Commit
git add -A && git commit -m "refactor: rename OldAPIClient to NewAPIClient"

Best Practices

-Always preview with rg before applying sed
-Use -l to get file list (pipe to xargs sed for replacement)
-Create a git branch before bulk replacements
-Verify with rg after replacement (no remaining old references)
-Run tests after refactoring
-Use -w for whole-word replacement (avoid partial matches)

Common Mistakes

-Replacing without previewing (unintended changes)
-Not using -w (replacing partial words: "user" -> "new_user" in "username")
-Forgetting to escape regex in sed (dots, slashes)
-Not verifying after replacement (broken references missed)
-Not running tests (replacement broke functionality)
-Using BSD sed syntax on Linux or vice versa

FAQ

Discussion

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How It Works

Step 1: Preview Matches

bash

# Find all matches first
rg "oldFunction" --type ts

# See context around matches
rg -C 2 "oldFunction" --type ts

# Count affected files
rg -l "oldFunction" --type ts | wc -l

# Preview replacement with --passthru
rg "oldFunction" -r "newFunction" --passthru --type ts

Step 2: Simple Replacement with sed

bash

# Replace in all matching files
rg -l "oldFunction" --type ts | xargs sed -i 's/oldFunction/newFunction/g'

# macOS (BSD sed requires backup extension)
rg -l "oldFunction" --type ts | xargs sed -i '' 's/oldFunction/newFunction/g'

# Safe replacement (create backups)
rg -l "oldFunction" --type ts | xargs sed -i.bak 's/oldFunction/newFunction/g'

# Multiple replacements
rg -l "oldAPI" --type ts | xargs sed -i \
  -e 's/oldAPI/newAPI/g' \
  -e 's/v1\/endpoint/v2\/endpoint/g'

Step 3: Regex Replacement with Capture Groups

bash

# Preview regex replacement (ripgrep -r flag)
rg "console\.(log|warn)\((.*)\)" -r "logger.$1($2)" --type ts

# Apply with sed (capture groups)
rg -l "console\.log" --type ts | xargs sed -i 's/console\.log(\(.*\))/logger.info\1/g'

# Rename CSS class prefix
rg -l "btn-primary" --type css | xargs sed -i 's/btn-primary/button-primary/g'

# Update import paths
rg -l "from '@/old-path/" --type ts | xargs sed -i "s|from '@/old-path/|from '@/new-path/|g"

Step 4: Safe Refactoring Workflow

bash

# 1. Create a branch
git checkout -b refactor/rename-api

# 2. Preview changes
rg "OldAPIClient" --type ts -C 1

# 3. Apply replacement
rg -l "OldAPIClient" --type ts | xargs sed -i 's/OldAPIClient/NewAPIClient/g'

# 4. Verify no missed references
rg "OldAPIClient" --type ts    # should return nothing

# 5. Check for broken references
rg "NewAPIClient" --type ts    # verify replacements look correct

# 6. Run tests
npm test

# 7. Review diff
git diff

# 8. Commit
git add -A && git commit -m "refactor: rename OldAPIClient to NewAPIClient"

Common Mistakes

-Replacing without previewing (unintended changes)

-Not using -w (replacing partial words: "user" -> "new_user" in "username")

-Forgetting to escape regex in sed (dots, slashes)

-Not verifying after replacement (broken references missed)

-Not running tests (replacement broke functionality)

-Using BSD sed syntax on Linux or vice versa