[ILUG] don't pass open file descriptor to children

[Colm Buckley]

On Friday 13 July 2001 17:07, Padraig Brady wrote:

> Oops should have been a bit more descriptive (pardon the pun).
> This has to be general (I don't have to source to the children).

I think you're confusing the process of exec() with that of fork()
(confusing processes with programs).  If you're writing the *parent*,
you *do* have access to the source of the child processes, because
after a fork(), the child process is running the *same* *code* as the
parent.  It's only after an exec(), which loads a new *program* into
the current *process*, that you've lost control of the source.

This should work:

            switch (pid = fork()) {
		   case -1 : /* error */
		   perror "fork() failed";
		   exit();
		   break;

		   case 0 : /* child process */
		   /* close FDs we don't want to pass to the new
		   program */
		   close(fd0);
		   close(fd1);
		   /* now run the new program */
		   execp("/path/to/program", "program", "arg1", "arg2", NULL);
		   perror("exec() failed");
		   break;

		   default : /* parent */
		   printf("Child launched with pid %d\n", pid);
		   break;
            }

Alternatively, as has been mentioned, you can use fcntl() to set the
F_SETFD flag on the file descriptors, which means they would be
automatically closed as soon as the exec() was done.

        Colm

-- 
Colm Buckley @ NewWorld Commerce
Business: +353 1 4334334  / colm at nwcgroup.com / http://www.nwcgroup.com/
Personal: +353 87 2469146 / colm at tuatha.org / http://www.tuatha.org/~colm/
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