Subject: Re: bug#36820: grep "[[:cntrl:]]" /proc/1/cmdline works on 2.20 but not 3.3

From: Paul Eggert <[email-masked]>
Date: Sat, 27 Jul 2019 10:16:00 -0700

This is documented behavior; the grep manual says that when grep is reading a 
binary file it "may treat non-text bytes as line terminators".

You can use grep's -a (--text) option to if you want to match null bytes.