Write a program for following system calls of UNIX operating system: fork, exec, getpid, exit, wait, close, stat, opendir, readdir .

#include<stdio.h>
main(int arc,char*ar[])

{

int pid;
char s[100];
pid=fork();

if(pid<0)
printf("error");

else if(pid>0)
{
  wait(NULL);
  printf("\n Parent Process:\n");
  printf("\n\tParent Process id:%d\t\n",getpid());
  execlp("cat","cat",ar[1],(char*)0); error("can’t execute cat %s,",ar[1]);

}

else
{

printf("\nChild process:");
printf("\n\tChildprocess parent id:\t %d",getppid());
sprintf(s,"\n\tChild process id :\t%d",getpid());
write(1,s,strlen(s));
printf(" ");
printf(" ");
printf(" ");
execvp(ar[2],&ar[2]);
error("can’t execute %s",ar[2]);
}

}