ls "$file" 2>/dev/null

qing

ls "$file" 2>/dev/null

in the above , what is 2 mean?
or what the above doing.


2>/dev/null redirects error messages to /dev/null. (2 = standard error).


http://www.experts-exchange.com/ ... nix/Q_11978478.html

qing

这样的文件描述符有12个，通常就用到3个：即：
0---标准输入
1--标准输出
2--标准错误

http://bbs.chinaunix.net/forum/4/20040116/245081.html