... to determine if color output should be enabled. If the variable is not set,
fall back to using on_tty(). Also, rewrite existing code to use
colors_enabled() where appropriate.
With this change we'll open the shell's tty right from machined and then
pass it to the transient unit we create. This way we make sure the pty
is opened exactly as long as the transient service is around, and no
longer, and vice versa. This way pty forwarders do not have to deal with
EIO problems due to vhangup, as the pty is open all the time from the
point we set things up to the point where the service goes away.
The internal speaker is usually not available on modern latops that
support suspend, and even if it is available in the hardware, most
distributions turned support for it off in the kernel. And even if it is
enabled, it's probably still a bad idea to make use of it for the
suspend-failures. If anything a proper sound should be played.
Long story short, let's remove support of this anachronism.
Let's underline the header line of the table shown by cgtop, how it is
customary for tables. In order to do this, let's introduce new ANSI
underline macros, and clean up the existing ones as side effect.
