请教linux高手 谢谢！！！

tomlong

18.Suggest two ways of repeating the last command issued without having to completely retype it.

19.Think of a suitable name for an alias for the command netscape & then define a command to create the alias.

20.If you wanted an alias to be available every time you logged on, where should you put the command which creates it?

Imagine that you have created, in your home directory, a directory called Coursework, then within this, you have created two directories, one called SDTD and the other called SDP.
a)
What command would you have used to create the directory Coursework?

b)
Within your SDTD directory, you have a file called cw1. Within your SDP directory, you have a directory called cw1, and within this a file called fish.java.
Write down the full pathnames of each of the files cw1 and fish.java.

12. Explain the terms standard input and standard output in the context of the Unix operating system

13. In Unix, what is the difference between a pipe and a filter?

14.Give a single line command which will send to a line printer a sorted list of who is currently logged on. (You may assume that the line printer is the default printer.

15.Assume that a file called staff.info contains a list of computing department staff, with name, room and phone number of each member of staff on a separate line.
What command would display on screen the entry for your personal tutor? You may assume that members of staff have unique surnames.

16.Explain the purpose of the Unix command chmod. Why should it be used with great care?


小弟是一位linux菜鸟，以上问题是小弟从英国大学的linux网站摘下来的一些练习题，小弟不知道怎样解答竟请各位高手赐教。。万分感谢！如果可以给与英文解更好，谢谢！