My flavour of ps (procps version 3.2.7) when run as ps -ef includes the total time that the process has used, so all output lines match the grep pattern.
Maybe:
This depends on the version of ps shifting the date in place of the time and when it does that; it might not be precise. I note on my system, processes that were started less than 24 hours ago, show Dec27 (rolls at midnight?), so if you really need all processes started in the last 24 hours you might turn to something like this:
This is a real hack, and probably won't work on every system (certainly needs the proc file system to be functional), but it does present every process that was started during the past 24 hours (using the time that you run this command pipeline) and not just since midnight which is what you'll get if you depend on filtering away things like Dec21.
---------- Post updated at 11:17 ---------- Previous update was at 11:15 ----------
Clearly the output format from this GNU/Linux version of "ps" is different from the default unix output format.
Actually not having a space character between Month and Day is so much better ! (It's a pain in unix).
Just for completeness it would be nice to see a sample for processes started today.
I can't say that a huge long grep -v is really the best way to approach this given that you may inadvertently match so many things, but then if it works, then I suppose that's all we all want.