The following Perl command, which should work directly in a UNIX/OSX bash, checks a file and prints any line with a non-ascii character
perl -ne 'print "$. $_" if m/[\x80-\xFF]/' file.txt
The following Perl command, which should work directly in a UNIX/OSX bash, checks a file and prints any line with a non-ascii character
perl -ne 'print "$. $_" if m/[\x80-\xFF]/' file.txt