On 10/19/06, Helliwell, Kim <[EMAIL PROTECTED]> wrote:
I would like the parent to continue independently of the child.
It sounds as if you want to use the double-fork trick. The first fork
produces a child process; this child forks a grandchild process, then
quits. The grandchild process does the work, and the original parent
process doesn't have to wait once the child quits.
On most Unix systems, the grandchild process will be "adopted" by
another process (conventionally init, process id 1) once its true
parent process is finished.
Since you want to have a pipe from the parent to the grandchild, you
should set that up before the double fork. I generally use Perl's pipe
function to make a pair of filehandles; after forking, the parent
closes the read handle and the grandchild closes the write handle (or
vice versa, if you want data flowing the other way). The grandchild
should re-open STDIN to the read handle before the exec, if I'm
correct about what you want; that might look something like this:
open STDIN, "<&READPIPE"
or die "Can't re-open STDIN to READPIPE: $!";
After that, the process started by the exec should inherit that STDIN
stream, reading whatever the parent sends down the write end of the
pipe.
A special caution is that if the reading process doesn't consume the
input quickly enough, the parent process will block when its output
buffer becomes full. If that becomes a problem for your application,
ask again; there are ways to work around that.
Hope this helps!
--Tom Phoenix
Stonehenge Perl Training
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
<http://learn.perl.org/> <http://learn.perl.org/first-response>
