This little changed code works perfectly fine on my system:
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
int main(int argc, char *argv[])
{
int num = atoi(argv[1]);
printf("Number of process to open is %d.\n", num);
int pid;
int i;
for(i = 0; i < num; i++)
{
pid = fork();
if(pid < 0) {
printf("Error");
exit(1);
} else if (pid == 0) {
//printf("Child (%d): %d\n", i + 1, getpid());
//char * const argv[] = {"/bin/xterm", NULL};
//char * const envp[] = {NULL};
execl("/usr/bin/xterm", "/usr/bin/xterm", NULL);
//exit(0);
}else {
wait(NULL);
}
}
return 0;
}