Shell Programming and Scripting

hello
i am new at the UNIX programin thing
and i have this assignment, which would look so easy for many of u
the shell must do the followin thing:

exec parameter < input > output
and another 1
exec parameter < input | exec2 parameter > output

the teacher started it wiz the followin codin:

int main(int argc,char **argv){
pid_t pid; int status,nc;
char *buf; char **args;
buf=(char *)malloc(1024);
while (1){
printf("myShell$");fflush(stdout);
nc=read(0,buf,1024); args=parse(buf);
buf[nc-1]=0;pid=fork();
if(pid==0){
execvp(args[0],args);
printf("execvp failed\n");
}
else {
wait(&status);free(args);
}}}

can any one plzz help me to continue it?
usin simple codin,plz

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