CS155 HW4: Unit Conversion

Summary

The traditional system of measurements, as used in the U.S.A., is the best! It’s so simple to understand! “meters”—who needs ’em? We have yards, furlongs, miles, and leagues! ☹

In this assignment, you will write a bash script called unity which will do some length conversions. Specifically, it will recognize these units:

Unit	Conversion
inches
hands	4 inches
feet	12 inches
yards	3 feet
furlongs	220 yards
miles	5280 feet
leagues	3 miles
au	92,955,807 miles

You only have to recognize those names, which are all plural. You don’t have to recognize “foot” or “mile”. No other units (meters, angstroms, light-years, etc.) should be recognized.

Sample runs:

    % ./unity 4 feet as inches
    4 feet = 48 inches
    % ./unity 10 miles as feet
    10 miles = 52800 feet
    % ./unity 17 furlongs as furlongs
    17 furlongs = 17 furlongs
    % ./unity 3 yards as feet
    3 yards = 9 feet
    % ./unity 10 feet as yards
    10 feet = 3 yards
    % ./unity 1 au as inches
    1 au = 5889679931520 inches
    % ./unity
    usage: ./unity <number> <units> as <units>
    % ./unity XYZ inches as feet
    usage: ./unity <number> <units> as <units>
    % ./unity 1X inches as feet
    usage: ./unity <number> <units> as <units>
    % ./unity 1 inches as feet extra stuff here
    usage: ./unity <number> <units> as <units>
    % ./unity 3 yard as feet
    Unrecognized unit: yard
    % ./unity 1 feet as meters
    Unrecognized unit: meters

Your program will convert between all pairings of those units. That is, the second and fourth arguments can be any of the recognized units.

Requirements

This must be a pure bash script, and not use any other languages such as perl, awk, or csh.
You may use programs such as expr or grep.
The first line of your script must be:
#! /bin/bash
You must emit the error messages, as shown above, when the wrong number of arguments are given, bad arguments are given, the word “as” is absent, or a non-numeric argument is given for the first argument. In such a case, no other output should be produced.
I realize that “1 miles as feet” is grammatically incorrect. We’ll live with that.
We’re dealing with integers, here. Note the result for “10 feet as yards”, above. It’s 3, not 3.333333.
Similarly, “2 feet as yards”, would yield 0, not 0.666666.

How to submit your homework:

Follow the directions on the homework page.

How to receive negative points:

Turn in someone else’s work.

CS155: Introduction to Unix

Spring 2013

HW 4

CS155 HW4: Unit Conversion

Summary

Sample runs:

Requirements

How to submit your homework: