Below is a description of what im trying to achieve:

Write a shell script to concatenate lists together, and output the resulting list. Do not include any argument that is a sub-list of the entire list. (The script will clean the list of any redundant items.) You must preserve the original order of the list. Remember to account for the following situations:

# a : at the beginning of the list is the same as a . at the beginning of the "list" (:/bin is the same a .:/bin)

# a :: any where in the list is the same as :.: (/bin::/etc is the same as (/bin:.:/etc)

# a : at the end of the list is the same a :. ( /bin: is the same as /bin:. )

The input to the script will be colon or space separated lists and the output will be a single colon separated list with all redundant items removed.

Examples:

prompt> clean_list a a:b a:b:c :x: y:z
a:b:c:.:x:y:z

prompt>clean_list applerange:apple pear orange peach
applerangeeareach

The following code is where im at right now but i'm not quite getting the desired results. for example, when i try the first example above i get a result of a:b:c:x:y:z (not the a:b:c:.:x:y:z)

#!/bin/sh

for P in `echo $* | sed -e 's/^:/.:/' -e 's/::/:.:/' -e 's/:$/:./' -e 's/:/ /g'`

do
case $NP in

"") NP="$P"
;;

$P|$P:*|*:$P:*|*:$P) continue
;;

*) NP="$NP:$P"
;;

esac

done

echo $NP

Any suggestions are appreciated!!!!!

Why do want to do this - is this a real world problem or just a homework assignment?
Mike

Replace all spaces by : in your sed command
You can group all the -e options :