When I thought you always wanted to work on three directories, I started working on the following script:

Code:

#!/bin/ksh
IAm="${0##*/}"
if [ $# -ne 3 ]
then    printf "Usage: %s dir1 dir2 dir3\n" "$IAm" >&2
        exit 1
fi
if [ ! -d "$1" ] || [ ! -d "$2" ] || [ ! -d "$3" ]
then    printf "%s: All three operands must be directories\n" "$IAm" >&2
        exit 2
fi
if [ "x${2:0:1}" = x/ ]
then    d2="$2"
else    d2="$PWD/$2"
fi
if [ "x${3:0:1}" = x/ ]
then    d3="$3"
else    d3="$PWD/$3"
fi
if ! cd "$1"
then    printf "%s: Can't change directory to \"%s\"\n" "$IAm" "$1" >&2
        exit 3
fi
for i in *
do      if [ ! -e "$d2/$i" ]
        then    if [ ! -e "$d3/$i" ]
                then    printf "Only in %s: %s\n" "$1" "$i"
                else    printf "Only in %s and %s: %s\n" "$1" "$3" "$i"
                 fi 
        else    if [ ! -e "$d3/$i" ]
                then    printf "Only in %s and %s: %s\n" "$1" "$2" "$i"
                fi
        fi
done

which produces the output:

Code:

Only in dir1: 2.txt
Only in dir1 and dir3: 5.txt
Only in dir1: 6.txt

for the directory hierarchy given in the 1st message in this thread when it is saved in a file named tester and invoked as:

Code:

./tester dir1 dir2 dir3
    or
./tester dir1 dir3 dir2

Note that it was written using the Korn shell, but it uses an extension not specified by the standards (${var:start:length} to get a substring from a variable). This is at least available in recent versions of bash and ksh versions more recent that November 16, 1988.

Your specification of the output you wanted is very vague, so this might not even be close to what you want; but I hope it will give you some idea of how to approach your problem.

If you want us to pursue your new, more general problem with an unlimited number of directories and unspecified combinations of comparisons, you need to give a much more detailed description of what you want to happen, how you want to specify the options and operands for this command, and how you want the output formatted. Try to write a man page describing the utility you want to create.