Diff for "BashFAQ/008"

How can I recursively search all files for a string?

If you are on a typical GNU or BSD system, all you need is one of these:

   1 # Recurse and print matching lines (GNU grep):
   2 grep -r -- "$search" .
   3 
   4 # Recurse and print only the filenames (GNU grep):
   5 grep -r -l -- "$search" .

If your grep lacks a -r option, you can use find to do the recursion:

   1 # Portable but slow
   2 find . -type f -exec grep -l -- "$search" {} \;

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:

   1 # Fast, but requires a recent find
   2 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-2008 find, which most current operating systems have, but which may not be available on legacy systems.

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

   1 # DO NOT USE THIS
   2 find . -type f | xargs grep -l -- "$search"

However, if your filenames contain spaces, quotes or other metacharacters, this will fail catastrophically. BSD/GNU xargs has a -print0 option:

   1 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.

CategoryShell