[HECnet] PyDECnet setup

On Thu, Nov 18, 2021 at 12:20 PM Dave McGuire <mcguire at neurotica.com> wrote: The use of SIGHUP to reread a config file comes from, at least, Unix 5th Edition. I suspect that the practice originated with the `init` process (usually PID 1) which, on receipt of SIGHUP, would reread the ttys file to figure out what typewriters were attached to the system. Prior to that, I suspect they'd have to reboot to add a new terminal to the system, but things from first through 4th edition are not as well preserved as 5th onwards, so its hard to tell. By the time Berkeley was writing things like inetd, the practice was well known. Does that make it a "standard?" Not in any formal sense, but a daemon couldn't receive a SIGHUP in the usual way an interactive process might, so piggybacking some special meaning on it makes a certain amount of sense. Has it fallen out of a favor? A bit. As Doug McIllroy put it on the Unix Heritage Society list a few years ago, signal() primarily existed to support SIGKILL, not as a principled basis for IPC. It's racy and doing Real Work in the context of an upcall from the kernel like a signal handler is fraught. - Dan C.