> is it "normal" that a simple 'kill' won't kill PicoLisp processes, only
> with option 'KILL it works?
A "normal" kill with SIGTERM (i.e. -15) should work.
SIGKILL (i.e. -9) should be used only in extreme emergencies, because it
may cause the loss of data (resulting in a corrupted database in the
$ killall picolisp
$ killall pil
It should be noted, however, that PicoLisp catches some signals:
1. SIGPIPE, SIGTTIN and SIGTTOU are ignored.
2. SIGIO is caught and handled in the 'sigio' function handler.
3. SIGHUP is caught and handled in the '*Hup' global.
4. SIGUSR1 and SIGUSR2 are handled in the '*Sig1' and '*Sig2'
5. SIGALRM is used for the 'alarm' and 'abort' functions.
6. SIGCHLD is handled internally for the management of child
7. SIGINT is caught only in the REPL, and causes a console break. A
process running without a REPL is terminated.
8. SIGTSTP is used in the REPL to suspend the forground PicoLisp
The "normal" (default) signal SIGTERM causes the termination of the
running PicoLisp process with 'bye'.
1. If that process has still running child processes, it sends
SIGTERM recursively to all children first, and waits for them to
terminate. Then it terminates itself.
2. During certain phases of program execution, the PicoLisp
interpreter blocks this and/or other signals. This may be in a
'protect'ed code block, or during critical database operations.
This will only delay the handing of those interrupts (not ignore
I hope I didn't forget anything :)