Simonelinux中的read -t 5命令做什么用的，他的意思是的read 5秒后自动退出，但是为什么要自动退出
的有关信息介绍如下：
read (1p) - read a line from standard input
read (2) - read from a file descriptor
read (3p) - read from a file
read [builtins] (1) - bash built-in commands, see bash(1)
read-expenses (1) - Connect to the Palm handheld and dump the Expense application data in a simple format
read-ical (1) - coverts information on your Palm handheld into an Ical-formatted calendar. Note, this is not the same as the iCal calendar format
read-notepad (1) - Connect to the Palm handheld and list the record information found in the Palm Notepad application (found on OS4 and newer devices). Alternately, if no options are given, each record's image will be converted to files, using Portable Network Graphic (.png) or Portable Pixmap (.ppm) format. The default type is ppm
read-palmpix (1) - Convert all pictures in the files given or found via connecting to a Palm handheld if no files are given. The default output type is Portable Pixmap (.ppm)
read-todos (1) - Syncronize your Palm ToDo application's database with your desktop machine
以上是解释：read的作用
下面是read的各个选项的参数：
root@Linux ~]# read --help
-bash: read: --: invalid option
read: usage: read [-ers] [-u fd] [-t timeout] [-p prompt] [-a array] [-n nchars] [-d delim] [name ...]
