Linux – Using grep to find a string in files

And the always popular

find . -name '*.java' | xargs grep -l 'string'

EDIT (by Frank Szczerba):

If you are dealing with filenames or directories that have spaces in them, the safest way to do this is:

find . -name '*.java' -print0 | xargs -0 grep -l 'string'

There's always more than one way to do it.

In Bash:

for file in *; do [[ "$(head -1 "$file")" =~ ^\<\? ]] || echo "$file"; done

Make sure they are files:

for file in *; do [ -f "$file" ] || continue; [[ "$(head -1 "$file")" =~ ^\<\? ]] || echo "$file"; done