multipipe starts one supervise process for each subdirectory of the current
multipipe skips subdirectory names starting with dots.
Each supervised processes is piped a copy of standard input sent to
Every five seconds,
multipipe checks for subdirectories again.
If it sees a new subdirectory, it starts a new supervise process.
If a subdirectory is removed, it closes the pipe to that supervise
supervise or with names starting with a period are ignored.
multipipe is given a command-line argument, it switches to that directory when it
multipipe is sent either the
QUIT, or the
TERM signal, or it reaches end of file on standard input, it runs
svc -dx on each command to shut it down, and waits for it to exit.