shell中tee命令

linux tee 命令详解
功能：读取标准输入的数据，并将其内容输出成文件。

-a或–append 　附加到既有文件的后面，而非覆盖它．

[root@localhost ~]# who | tee who.out
root pts/0 2009-02-17 07:47 (123.123.123.123)
[root@localhost ~]# cat who.out
root pts/0 2009-02-17 07:47 (123.123.123.123)
[root@localhost ~]# pwd | tee -a who.out
/root
[root@localhost ~]# cat who.out
root pts/0 2009-02-17 07:47 (123.123.123.123)
/root