COP 3344-01 Introduction to Unix: Lecture 6

Learning objectives

After this class, you should be able to:

1. Write shell scripts that use the Bourne shell, and run them. In particular, you should be able to use the following features: (i) case, (ii) exit, (iii) for, (iv) if, and (v) while.

Reading assignment

1. JEA: Chapters 33.11-33.16, 33.18, Single Unix Specification for definitions of the commands.
2. Lecture slides: Lecture 6.

Exercises and review questions

• Questions on current lecture's material
  1. The shell script myrm3 requires one argument. Add a few statements to the beginning of this script so that it outputs an error message and the correct usage to stderr, if the user does not supply exactly one command line argument.
  2. The shell script backup expects at least one argument. Add a few statements to the beginning of this script so that it outputs an error message and the correct usage to stderr, if the user does not supply exactly at least one command line argument.
  3. Write a shell script called firstword which is run as follows: ./firstword filename word1 word2. It outputs the line number of all lines in the file filename which start with either word1 or word2. Each line of the output has the following format: Line # <n> starts with <word>, where <n> is the line number and <word> is either word1 or word2. Use the case statement in this shell script. Do not use the grep utility.

• Questions on next lecture's material
  1. None.