#include <unistd.h>int main(){    char buffer[128];    int nread;    nread = read(0, buffer, 128);    if (nread == -1)        write(2, "A read error has occurred\n", 26);    if ((write(1,buffer,nread)) != nread)        write(2, "A write error has occurred\n",27);    exit(0);}