chmod(file,mode)

• The first number is always zero
  第一个数字通常是0
• The second number specifies permissions for the owner
  第二个数字指定所有者的特许
• The third number specifies permissions for the owner's user group
  第三个数字指定所有者用户群特许
• The fourth number specifies permissions for everybody else
  第四个数子指定了所有人的特许

Possible values (to set multiple permissions, add up the following numbers):
可用值（为了设置多组特许，可以通过添加下面的数字）

• 1 = execute permissions
  1 = 执行特许
• 2 = write permissions
  2 = 可写特许
• 4 = read permissions
  4 = 可读特许

<?php
// Read and write for owner, nothing for everybody else
chmod("test.txt","0600");

// Read and write for owner, read for everybody else
chmod("test.txt","0644");

// Everything for owner, read and execute for everybody else
chmod("test.txt","0755");

// Everything for owner, read for owner's group
chmod("test.txt","0740");
?>