CS1101: Laboratory 6(b) A useful shell script - usage Academic Year 2006-2007 Lecturer: Dr. Barry O'Sullivan Department of Computer Science University College Cork b.osullivan@cs.ucc.ie

Objective of this Lab

To familiarise students with the concepts of shell scripts.

This lab is based on material from Paul Andersen's book entitled "Just Enough UNIX".

Submission

During this lab you will be asked to write 1 shell script of your own. It must be submitted by 5pm Friday the 8th of December (Friday of this week).

Background

All shell scripts that you write, for this course, should be based on the sh shell. A reference on this shell is available online.

Tasks

You should write and submit a shell-script that meets the following specification.

Computing the size files or directories

You are required to write a shell script called usage which has the following specification:

• Name: usage - reports the size of the file passed as an argument, or lists the contents of the a directory with the sizes of each entry.
• Syntax: usage
• Description: This is the outline for usage:
  1. This shell script should report the type and disk usage of a given file or directory in kilobytes;
  2. The du-sk command can be used to report the size of a file
  3. Directories are more complicated because you need to sum the sizes of the files and also of the sub-directories. However, the size of a sub-directory can be obtained from the command du -sk - read the manual page for du to get information on this command.
  4. To identify a file you can use test -f, while test -d can be used to identify a directory. Use will need if and for statements here.
  5. An example of the required output is given below. In the case of a directory you need to not only say how large the entire directory is, but also list the sizes of the elements within it. to

Example:

bash> usage Mail
Mail is a directory
It's total size is 100kb
Contents:
cs1101 (file) 10kb
friends (file) 100kb 
backup (directory) 110kb
bash>
bash> usage usage
usage is a file
It's size is 4kb
bash>

Submission

Submit your script using the following command:

cs1101submit usage

b.osullivan@cs.ucc.ie

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