A code-specific searching tool similar to ack, but faster.
By default, you can use it to search for a given pattern in all files under a directory tree.
You can modify it with
-g to search for files with names matching the given pattern (similar to
find | grep, but much faster).
ag -g '.+swift' returns all files ending in “swift”.
You can modify it with ‘-G’ to search for pattern in all files with names matching a pattern.
ag -G '.+swift' Foo searches for the pattern ‘Foo’ only in files ending in “swift”.