grep only text files

You can use the -r(recursive) and -I(ignore binary) options in grep:

$ grep -rI "TEXTSEARCH" .

• -I Process a binary file as if it did not contain matching data; this is equivalent to the --binary-files=without-match option.
• -r Read all files under each directory, recursively; this is equivalent to the -d recurse option.

If you know what the file extension is that you want to search, then a very simple way to search all *.txt files from the current dir, recursively through all subdirs, case insensitive:

grep -ri --include=*.txt "sometext" *

Another, less elegant solution than kevs, is, to chain -exec commands in find together, without xargs and cut:

find . -type f -exec bash -c "file -bi {} | grep -q text" \; -exec grep TEXTSEARCH {} ";"