Shell and Perl Script assignment

In both bourne shell and perl, write a script to do the following:

Given a colon separated list (ala .c $PATH ) as an argument, print out a revised list with all duplicates removed. This list must be in the same order as the original list. Also, make sure to preserve empty list entries. For example:

$ pathfix a:b:c:b:d:a:a:b:e::f
a:b:c:d:e::f
$ pathfix :a:a:a:a::a:
:a

For those wanting to explore further, expand this program to support the following operations:

• add elements on either end of a list
• remove an element from a list
• make the first part of this assignment optional (i.e. an extra option to turn this behavior off)