Code:
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
int main()
{
pid-t pid;
/* fork a child process */
pid = fork();
if (pid < 0) {/* error occurred */
fprintf(stderr, "Fork Failed");
exit (-1) ;
}
else if (pid == 0} {/* child process */
execlpf"/bin/Is","Is",NULL);
}
else {/* parent process */
/* parent will wait for the child to complete */
wait(NULL);
printf("Child Complete");
exit (0) ;
which is a unique integer. A new process is created by the forkO system
call. The new process consists of a copy of the address space of the original
process. This mechanism allows the parent process to communicate easily with
its child process. Both processes (the parent and the child) continue execution
at the instruction after the f ork(), with one difference: The return code for
the forkO is zero for the new (child) process, whereas the (nonzero) process
identifier of the child is returned to the parent.
Typically, the execO system call is used after a forkO system call by
one of the two processes to replace the process's memory space with a new
program. The exec () system call loads a binary file into memory (destroying
the memory image of the program containing the execO system call) and
starts its execution. In this manner, the two processes are able to communicate
and then go their separate ways. The parent can then create more children; or,
if it has nothing else to do while the child runs, it can issue a wait () system
call to move itself off the ready queue until the termination of the child.
