将标准输入复制到标准输出

 1 #include "apue.h"
 2 #define    BUFFSIZE    4096
 3 int
 4 main(void)
 5 {
 6     int        n;
 7     char    buf[BUFFSIZE];
 8     while ((n = read(STDIN_FILENO, buf, BUFFSIZE)) > 0)
 9         if (write(STDOUT_FILENO, buf, n) != n)
10             err_sys("write error");
11     if (n < 0)
12         err_sys("read error");
13     exit(0);
14 }