Control characters in file names

You repeat at least three times in the thread that it takes hundreds of lines to handle control characters in shell scripts. That's just not true. But worse, it's a terrible argument even if it were true.

You aren't proposing to remove all the characters that make it difficult to write correct shell scripts. In fact tab and newline and the worst "offenders" in your list of control characters. Most shells don't care about control characters at all. This can't be an argument for implementing the character set limitation because implementing it won't fix the problem -- the same script would still be broken by files with spaces in them (and any number of shell metacharacters).

And even if it did, I'm not sure the features of Bourne shell should dictate how the filesystem interface should work. The existing kernel and shell were designed together -- if you want to redo the filename encoding in the kernel, you should consider how the shell could be changed and also how other tools besides the shell are affected. Only looking at the shell is just too much focus.