how to search a file or a text in file in the current folder and in all the subfolders using grep commond?

Question

i have to search for a particular text in files and for that im using grep command but it searches only in current folder.What i want is that using a single grep command i can search a particular thing in the current folder as well as in all of its sub folders.How can i do that???

Answer 1

man grep says

   -R, -r, --recursive
          Read all  files  under  each  directory,  recursively;  this  is
          equivalent to the -d recurse option.

Answer 2

POSIX grep does not support recursive searching - the GNU version of grep does.

find . -type f -exec grep 'pattern' {} \;

would be runnable on any POSIX compliant UNIX.