Find files containing a given text

egrep -ir --include=*.{php,html,js} "(document.cookie|setcookie)" .

The r flag means to search recursively (search subdirectories). The i flag means case insensitive.

If you just want file names add the l (lowercase L) flag:

egrep -lir --include=*.{php,html,js} "(document.cookie|setcookie)" .

Try something like grep -r -n -i --include="*.html *.php *.js" searchstrinhere .

the -i makes it case insensitlve

the . at the end means you want to start from your current directory, this could be substituted with any directory.

the -r means do this recursively, right down the directory tree

the -n prints the line number for matches.

the --include lets you add file names, extensions. Wildcards accepted

For more info see: http://www.gnu.org/software/grep/