As a bash extension, you can do this: grep $'\t' * Also, you can put a literal tab between quotes to the command (in a script, I did that with a literal \x1b once); in the interactive command line, you can insert a tab with c-Vc-I.

However, I have my cgrep: Egrep clone with function name display installed on my system, so I can just type cgrep '\t' *.