Diff for "BashFAQ/008"

How can I recursively search all files for a string?

90% of the time, all you need is one of these:

# Recurse and print matching lines (GNU grep):
grep -r "$search" .

# Recurse and print only the filenames (GNU grep):
grep -r -l "$search" .

You can use find if your grep lacks a -r option:

find . -type f -exec grep -l "$search" {} \;

The {} characters will be replaced with the current file name.

This command is slower than it needs to be, because find will call grep with only one file name, resulting in many grep invocations (one per file). Since grep accepts multiple file names on the command line, find can be instructed to call it with several file names at once:

find . -type f -exec grep -l "$search" {} +

The trailing '+' character instructs find to call grep with as many file names as possible, saving processes and resulting in faster execution. This example works for POSIX find, e.g. with Solaris, as well as very recent GNU find.

Traditional Unix has a helper program called xargs for the same purpose:

find . -type f | xargs grep -l "$seach"

However, if your filenames contain spaces or other metacharacters, you'll need to use the BSD/GNU -print0 option:

find . -type f -print0 | xargs -0 grep -l "$search"

The -print0 / -0 options ensure that any file name can be processed, even one containing blanks, TAB characters, or newlines.