Homework & Coursework Questions

1. The problem statement, all variables and given/known data:

Write a script that asks for 4 arguments, and the 1st and 3rd need to be -i and -o, and the 2nd/4th need to be file names.

Technically, it's supposed to be run as:
./Lab_14.sh -i input.txt -o output.txt

Depending on how many arguments are used, and what the arguments are, error messages will pop up (ie- too many/few arguments, not an existing filename, etc etc etc)

2. Relevant commands, code, scripts, algorithms:

Required Errorlevels

Errorlevel# Event Information

0 Script functions correctly
10 No arguments provided on command line (=0)
11 First argument missing (=0)
12 First argument present, but not what expected (“-i”)
13 Second argument missing on command line
14 Second argument present, but file does not exist
15 Third argument missing on command line
16 Third argument present, but not what expected (“-o”)
17 Fourth argument missing on command line
18 Too many arguments provided on command line (>4)

Variable Interpolation

The script must be as dynamic as possible. Variables are to be used for command line arguments, user input, and generated output throughout the script. Hard-coded values, where variables can be used, are unacceptable.



3. The attempts at a solution (include all code and scripts):

Code:

#!/bin/bash
echo

proper="Usage:  ./Lab_14.sh -i <infile> -o <outfile>

-i <infile>   The filename containing the existing data.
-o <outfile>  The filename you want the output"

if [ "$1" == "" ] ;then
	echo "You must input the first argument."
	echo
	exit 11
fi

if [ "$1" != "-i" ] ;then
	echo "Error: Expecting \"-i\" for the first argument."
	echo
	exit 12
fi

if [ "$3" != "-o" ] ;then
	echo "Error: Expecting \"-o\" for the 3rd argument."
	echo
	exit 16
fi

if [ "$3" == "" ] ;then
	echo
	echo "You must input the third argument."
	echo
	exit 15
fi

if [ "$2" == "" ] ;then
	echo "You must enter a file name."
	echo
	exit 13
fi

if [ ! -e "$2" ] ;then
	echo "$2 does not exist, please enter a real file."
	echo
	exit 14
fi

if [ "$#" == "0" ] ;then
	echo
	echo "Error: No arguments present at all."
	echo
exit 10
fi

if [ "$#" -ge "5" ] ;then
	echo
	echo "Error: Too many arguments"
	echo
exit 18
fi

if [ "$4" == "" ] ;then
	echo
	echo "Error: Fourth argument is missing."
	echo
	exit 17
fi

if [ -e "$4" ] ;then
	echo
	echo "File \"$4\" exists already.  Overwriting contents."
	echo
fi


if [ "$?" != "0" ] ;then
	echo
	echo $proper
	echo
fi

	cp $2 $4
	echo
	echo "Correct amount of arguments provided ..."
	echo
	echo "First argument was: " $1""
	echo "Second argument was: "$2""
	echo "Third argument was: " $3""
	echo "Fourth argument was: "$4""
fi

exit 0

4. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course):

Mohawk College, Hamilton, ON, Canada, Cheryl Weaver, dunno my course number right now

---------- Post updated 03-29-10 at 10:52 AM ---------- Previous update was 03-28-10 at 05:34 PM ----------

ignore my nonsense, I fixed it after a marathon of vi editing