The trouble with SIGUSR1 is that the default action is terminate, so you can only send it to processes you know will take it well. It's safe to send SIGINFO to

The trouble with SIGUSR1 is that the default action is terminate, so you can only send it to processes you know will take it well. It's safe to send SIGINFO to processes that don't know about it; the default action is to ignore it. You can send it to an entire process group, and maybe some of them will answer it. But even if they don't, they won't just get killed for it. This makes it so much more useful and discoverable, since you can almost always ^T with little risk. Usually you'll get at least a bit of information about how long the current command (more or less) has been running. If the running program happens to handle it, so much the better.