The following probably won't work as expected:
uniq requires that its input be sorted. The order of ip addresses generated by that command is likely to not be properly sorted. Even if it happens to be, it may not be guaranteed.

While it's harmless in this instance, the sed regular expression is probably more promiscuous than intended. The unescaped, leading dot is matching anything, not just a dot.

The grep|awk|sed|cut|sed|sort|uniq pipeline can be replaced by a single awk invocation:

Code:

awk '/inet addr/ && $2!="127.0.0.1" && !a[$2]++ {sub(/\.[^.]*$/, "", $2); print substr($2,6)}'

Although a single awk invocation is more efficient, unless a large amount of data is being processed, the performance gain is of no importance. Naturally, that awk will give incorrect results if the equivalent pipeline it replaces is itself incorrect.

The following is a clumsy way to iterate over a bash array.
Beyond that, it seems that y should be z or z should be y. y is never incremented in that loop. While the loop will execute once array member, it will invariably return the first the zeroth member. A simpler, more natural approach that would never have led to that bug:

Code:

for i in "${one[@]}";
do
    echo -e "$i\n"
done

Hopefully, something in this post is of some use to you. If not, provide us with more information such as your platform/operating system, sample output from the commands you're running (your ifconfig may not be the same as another's), and the problematic output versus the desired output ("the output gets mixed up." isn't at all helpful).

Regards,
Alister