replace is a command line utility for performing search-and-replace on files. It's similar to sed but there are a few differences:

• Modifies files when matches are found
• Recursive search on directories with -r
• Uses JavaScript syntax for regular expressions and replacement strings.

With node.js and npm:

npm install replace -g

You can now use replace and search from the command line.

Replace all occurrences of "var" with "let" in files in the current directory:

replace 'var' 'let' *

Replace in all files in a recursive search of the current directory:

replace 'var' 'let' . -r

Replace only in test/file1.js and test/file2.js:

replace 'var' 'let' test/file1.js test/file2.js

Replace all word pairs with "_" in middle with a "-":

replace '(\w+)_(\w+)' '$1-$2' *

Replace only in files with names matching *.js:

replace 'var' 'let' . -r --include="*.js"

Don't replace in files with names matching *.min.js and *.py:

replace 'var' 'let' . -r --exclude="*.min.js,*.py"

Preview the replacements without modifying any files:

replace 'var' 'let' . -r --preview

See all the options:

replace -h

There's also a search command. It's like grep, but with replace's syntax.

search "setTimeout" . -r

By default, replace and search will exclude files (binaries, images, etc) that match patterns in the "defaultignore" located in this directory.

If replace is taking too long on a large directory, try turning on the quiet flag with -q, only including the necessary file types with --include or limiting the lines shown in a preview with -n.