I'd like to grep a file for a string, but ignore any matches on lines that do not end with a trailing newline character. In other words, if the file does not end with a newline character, I'd like to ignore the last line of the file.

What is the best way to do this?

I encountered this issue in a python script that calls grep via the subprocess module to filter a large text log file before processing. The last line of the file might be mid-write, in which case I don't want to process that line.