The Emacs commands
find-grep-dired are all different interfaces for
grepping recursively into subdirectories. By default, they use the
command find to determine which files to work on, and either
run grep directly from find, or use xargs to batch
up files and reduce the number of invocations of grep.
Windows also comes with a find command, but it is not in any
way compatible with the POSIX find that Emacs tries to use.
Emacs expects a find compatible with GNU findutils.
See Other useful ports. After you have installed it, you will need
to make sure that Emacs finds this version, not the standard Windows
find command. You can do this by either renaming the
Windows command, changing your PATH to ensure that the directory
containing the findutils bin directory comes before the Windows
system directory, or set the variable
find-program to the full
path to the findutils find command.
An alternative if you have a recent version of grep is to customize
grep-find-command to use ‘grep -r’ instead of both find
and grep. Another alternative if you don't need the full capabilities
of grep is to use ‘findstr /n /r’.