Maybe there should be a new flag to open(2)

[Doug Gwyn <gwyn>]

More importantly, the kernel cannot reasonably perform
all the validity checking on files that applications
might require, so each such application needs to do this
anyway.

If I found out that some system utility program refused
to work on ptys or other non-ordinary files for no good
reason other than attempting to "protect" the naive user,
I would be quite upset and would probably rip out the
silly restriction.