synchronously shelling in c

[jcfuller]

How does one do a synchronous shell in c.

I want to run another application from mine and wait until it is finished before I continue.

I did look at exec but it appears to kill your process??

James

[blinky]

Use fork and then exec in the child process - I think.

[jcfuller]

I tried that but no-go. The After never prints
James

#include <stdio.h>
#include <unistd.h>


int
main (int argc, char **argv)

{
	pid_t pID = fork();
	int ret;
	printf("Before\n");
	
	ret = execlp ("/bin/ls", "ls", "-1", (char *)0);
	printf("After\n");
	return 0;
}

[blinky]

You have to do the exec in the child process. Also the parent process should wait for the child process to end.


man fork
man -s 2 wait

[jcfuller]

Got it:

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>

int
main (int argc, char **argv)

{
	pid_t pID,status;
	int ret;

	printf("Before\n");
	pID=fork();
	if (pID == 0)
	ret = execlp ("/bin/ls", "ls", "-1", (char *)0);

	while (wait(&status) != pID)
        /* empty */ ;	
	printf("After\n");
	return 0;

}