signals and suchlike

signals and suchlike

[schwartz]

Using rc-1.3b, some questions about signals...

; whatis sigint		# implicitly ignored, right?
sigint not found	# so why not say so?
; fn sigint {}		# set to ignored
; whatis sigint		# not the same?
fn sigint {}		# hmm

The man page says that signals are reset to their default
values in subshells.  CHANGES says that ignored signals
stay ignored.   It seems like the man page is correct, though:

; cat x
#!/bin/rc
whatis sigint
sleep 100000

; hup x		# hup runs x in the process group of the tty, so it
		# receives signals, but also sets sigint to sig_ign.
sigint not found
; ^C		# this kills x.

An analogous /bin/sh script behaves as expected.

Re: signals and suchlike

[Chris Siebenmann]

 The manual page is correct; ignored signals and default signals are
passed to children as-is, while signals that are caught to a function
are reset to default in children. This is slightly opaque in the manual,
but not very much (at least the signal section; perhaps there's wording
elsewhere).

	- cks

Re: signals and suchlike

[Chris Siebenmann]

 A bug in signal handling: rc unconditionally ignores a SIG_IGN'd
SIGINT, even if it's running a shell. It should not; if SIGINT is
ignored on entry to a shell script, rc should not change this. Only
when it's interactive is it entitled to play around with signals in
that way.

	- cks

Re: signals and suchlike

[Tom Culliton x2278]

There are a couple of problems with signal handling that Byron is
working on at the moment and will undoubtedly fix before 1.3 gets out
of beta.  I found that SIGINT seemed to be ignored but would work if
sent several time in quick succesion (by tap-tap-tapping ^C or whatever
you have it set to.)

Tom