Dear Maintainer,

$ tail -f
(normal tail -f behaviour follows)
$ tail -f --pid 32812
tail: warning: following standard input indefinitely is ineffective
(normal tail -f behaviour follows until 32812 dies)
$ tail -f $(tty)
(normal tail -f behaviour follows)
$ tail -f --pid 32812 $(tty)
(normal tail -f behaviour follows until 32812 dies)
$ tail -f < README
(normal tail -f behaviour follows)
$ tail -f --pid 32812 < README
(normal tail -f behaviour follows until 32812 dies)

What does any of this mean?
How can following a file be "ineffective"
(except in the case of, like, blockdevs, which are separately warned
 about and refused)?
How does "following indefinitely" differ from... following?
How could --pid /possibly/ mean "indefinitely" when it very much is the
exact opposite?
Why does following "standard input" differ in its "effectivenesss"
depending on file type?
How does following a teletype differ when you opened it yourself from
when someone else did?

наб