grep returns
Binary file test.log matches
For example
echo \"line1 re \\x00\\r\\nline2\\r\\nline3 re\\r\\n\" > test.log # in zsh
As James Selvakumar already said, grep -a does the trick. -a or --text forces Grep to handle the inputstream as text. See Manpage http://unixhelp.ed.ac.uk/CGI/man-cgi?grep
grep -a
try
cat test.log | grep -a somestring