//DAVID GARCÍA RUIZ
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

void main(int argc,char *argv[])

{
//funcion usage
int p[2];
int pid;
pipe(p);
int i;
for(i = 2; i<argc; ++i){
    pid = fork();
    if (pid == 0){
        dup2(p[1],1);
        close(p[0]); close(p[1]);
        execlp("cat","cat",argv[i],(char *)0);
        perror("execlp");
    }
    else if(pid<0); // falta error
    else waitpid(pid, NULL, 0);
}
pid = fork();
if (p == 0){ //GREP.
    close(p[0]);
    execlp("grep","grep", argv[1],(char *)0);
    perror("execlp");
}
    close(p[0]);
waitpid(pid,NULL,0);
}