First off: congrats! You got a working script. The following is written in the hope that it might interest you equally:

As it is, programming (yes, writing scripts is programming) is mostly about getting your thinking in order. Working code usually "falls out" of this process by itself. Most of the time while writing code is actually not spent writing, but planning: "what should the program do if ...".

Now, let us have a look at your program:

Yes, it did, what it should, so your basic requirement is fulfilled. How could it be made better?

First, you should habitually quote your strings - always:

Code:

filename=$1

This will break once "$var" contains a space char. Try it out:

Code:

var="oneword"
filename=$var               # this willl work
var="two words"
filename=$var               # but this will give an error message
filename="$var"             # yet, this will work regardless of what $var contains

The next thing is: you have covered the case that a user forgets to provide a filename. Now, what would your program do if the user provides a filename but it is not found (or is not readable, or not a regular file)? Wise programmers go to painful lengths to validate user input, because they know: if there is anything that can be trusted than it is the users ability to break things.

Read the man page of the test command to understand the following:

Code:

filename="$1"
# filename=${filename:?"Filename Missing, include the filename after the \"highest\" script as an arguement."}
if [ "$filename" = "" ] ; then
     print -u2 "Error: Filename Missing ..."
     exit 1
fi
if [ ! -f "$filename" ] ; then
     print -u2 "Error: File $filename does not exist or is not a regular file."
     exit 1
fi
if [ ! -r "$filename" ] ; then
     print -u2 "Error: File $filename is not readable."
     exit 1
fi

Finally, i suggest you create the variables you work with first. The shell does not require this (unlike like other programming languages, which do so), but it is still preferable to do so. You can make the variables have the appropriate type (integer or string) and you get an opportunity to document your code along the way:

Code:

#! /bin/ksh

typeset    filename=""               # filename to read from
typeset -i howmany=10                # number of lines to display

[...]

filename="$1"
# filename=${filename:?"Filename Missing, include the filename after the \"highest\" script as an arguement."}
if [ "$filename" = "" ] ; then
     print -u2 "Error: Filename Missing"
     exit 1
fi
if [ ! -f "$filename" ] ; then
     print -u2 "Error: File $filename does not exist or is not a regular file."
     exit 1
fi
if [ ! -r "$filename" ] ; then
     print -u2 "Error: File $filename is not readable."
     exit 1
fi

I hope this helps.

bakunin