Homework & Coursework Questions

Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!

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

Write a script that allows the user to print the first n lines or the last n lines of every file in the directory specified by the argument. e.g. lshead -head 2 Documents will print the first two lines of every file in the documents directory.


2. Relevant commands, code, scripts, algorithms:

Head command is used in this command as well as the tail command.

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

Code:

if [ $# -lt 0 ];
then
    echo "A directory name as an argument is expected"
    exit 1
fi

if [ $2 -lt 0 ];
then
        echo "expected a positive integer"
        exit 1
fi

if [ $1 = "-head" ];
then
    head -n $3

elif [ $1 "-tail" ];
then
    tail -n $3
else
         echo "Enter either head or tail"
         exit 1
fi
exit 0

I have run it and it comes up with this error:
head: Documents: invalid number of lines

I don't understand why it isn't working, I have even consulted friends on this and even they can't understand why it isn't working.

4. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course):
University of Huddersfield, Huddersfield, United Kingdom, Dr Gary Allen, CFT2112

Note: Without school/professor/course information, you will be banned if you post here! You must complete the entire template (not just parts of it).

What are you typing into unix?

Code:

myscript 1 2 3

or something similar, to start your script and pass parameters.

I type in

Code:

lshead -head 2 Documents (or whatever directory I want)

$0 = lshead command
$1 = -head/-tail
$2 = numeric value
$3 = directory

Isn't that error message highly meaningful? Look at the positional parameter that you supply to the commands.

---------- Post updated at 18:18 ---------- Previous update was at 18:17 ----------

And, why do you expect a negative parameter count?

I just put the $2 command there so that if a negative integer was entered, then it would prompt the user to enter a positive one.

And what about if the given directory were empty or contain binaries?
And to say the truth I doubt tail/head work on directories...

We haven't been told about what would happen if it was empty or contained binaries.

This is one of the commands I have been set so it must work surely.