On 24 Jan 2001, at 20:12, Charles Steinkuehler wrote:
> Take a look at my shell-script e-mail client, where I do pretty
> much what you want, with a few extra features (look for the mail
> procedure):
> http://lrp.steinkuehler.net/Packages/files/Utilities/grep
Thanks I'll look...
> The mainline code fires off a couple sub-processes that acutally
> does the work. The main code then goes into a timeout loop (sleeps
> for 1 second, increments a counter, checks to see if the children
> have finished). If the timeout counter ever expires, the mainline
> code kills all the (presumably hung) children. The child process
> can send a signals to the mainline code to indicate it's still
> alive, but things are taking a while, or that a problem has occured
> and we should promptly exit.
In my situation, the "sleeper" process is a spawned process; in
your case, the "sleeper" is the process which spawned the others.
I don't know if I could flip things around, since I require the script to
have access to the tty and to stdin - which a background process
won't - it would say "process X stopped [tty input]" or something
like that.
I've considered pipes or file-based locks/communications, but that
seems like overkill.
Maybe if I had specific questions:
* If a process is killed, are all of the children killed? If not, how do I
do this?
* If I want to have a parent process exit before the child is done,
how do I do this?
* The program sleep doesn't seem to abort if it's parent (?) is sent a
signal. How do I get the signal to propogate?
.................................Ummm...
For discussion's sake, I think I'll leave those questions in there.
My answer was this program:
killall sleep
and a well-placed redirection or two, as well as ignoring signals.
Here is the revised method:
1. Spawn a sleeper process: sleep X ; kill -1 $$
2. trap on 0 1 2 15
3. get input
4. three possible actions:
4a. receive input: exit normally, print input to stdout - to be
captured by VAR=$(timedread <n> <prompt>)....
4b. receive interrupt signal (^C) - exit status 2
4c. timedout: exit status 1
The standard exit is this:
trap '' 1 2 15 # ignore signals - such as those generated by killall
killall sleep 1>&2 2> /dev/null # kill current sleep (quietly! even if
error)
exit with status
The sleeper process was more completely this:
( sleep 2>&1 > /dev/null ; kill -1 $$ 2>&1 > /dev/null ) 1>&2 2>
/dev/null &
In other words, TOTAL silence :-)
How does this differ from what you did?
--
David Douthitt
UNIX Systems Administrator
HP-UX, Linux, Unixware
[EMAIL PROTECTED]
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