question about using G_system command

[Michael Shapiro]

What Unix box are you using? I have never known G_system() to fail before.
Perhaps they way the system() call has to be implemented on your platform
differs from the way other version of Unix do it? Here is the G_system()
call. As far as I can tell it should be identical to the way system()
is implemented except for the signal handling (which is added).
/****************************************************************/

#include <signal.h>
#include <stdio.h>

G_system (command)
    char *command;
{
    int status, pid, w;
    void (*sigint)(), (*sigquit)() ;              /* new */

    sigint  = signal (SIGINT,  SIG_IGN);          /* new */
    sigquit = signal (SIGQUIT, SIG_IGN);          /* new */

    fflush (stdout);
    fflush (stderr);

    if ( (pid = fork()) == 0)
    {
	signal (SIGINT,  SIG_DFL);                /* new */
	signal (SIGQUIT, SIG_DFL);                /* new */

	execl ("/bin/sh", "sh", "-c", command, 0);
	_exit(127);
    }

    if (pid < 0)
    {
	fprintf (stderr, "WARNING: can not create a new process\n");
	status = -1;
    }
    else
    {
	while ( (w = wait (&status)) != pid && w != -1)
	    ;

	if (w == -1)
	    status = -1;
    }

    signal (SIGINT,  sigint);                /* new */
    signal (SIGQUIT, sigquit);                /* new */

    return (status);
}

|
|
|I am trying to use G_system command to fork a process or to call
|an external module. It does not seem to work. However if I use system call
|it does work. Any one can explain why it is doing?
|
|Thanks.
|
|Srinivasan.
|srin at brcsun1.tamu.edu
|
|


-----------------------------------------------------------------
Michael Shapiro                        U.S. Army CERL                  
email:   shapiro at zorro.cecer.army.mil  Environmental Division          
phone:   (217) 352-6511  ext 526       P.O. Box 9005                   
fax:     (217) 373-7222                Champaign, Ill. 61826-9005
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