In D21426, I removed phd.trace and phd.verbose.

We may still reach calls to posix_isatty(STDOUT) and possibly posix_isatty(STDERR) after those pipes have closed. It's possible we can also reach posix_isatty(STDIN) with a closed stdin.

See also phutil_is_noninteractive() and phutil_is_interactive(), but the various posix_isatty() tests are really testing different things:

• Can we prompt the user interactively?
• Should we pipe output to a pager?
• Should we use ANSI console codes?
• Can/should we draw fancy high-I/O graphics (e.g. progress bars)?
• When daemonizing, should we close STDOUT/STDERR? (This is specific to HgProxyServer and attempting to test for "have they been redirected".)

All this stuff should probably (?) move to some ConsoleCapabilities class alongside phutil_console_get_terminal_width() and the broader ANSI support tests. A trick is that many of these tests have a common "we can't tell" state, and callers often want different default behaviors.

Another open question is: before we call posix_isatty(STDOUT), how do we test whether STDOUT is a valid handle?

Another open question is: before we call posix_isatty(STDOUT), how do we test whether STDOUT is a valid handle?

See also T13675. It seems like we can do some flavor of this:

$handle = fopen('php://stdout', ...);
if ($handle !== false) {
  posix_isatty($handle);
}