Here is the breakdown. The echo will output whatever is in the
variable $ipaddr This is then piped through to the following
command. Cut can be used to delimit (i.e. split into parts) a
string. A parameter to cut tells it where to "cut" the string
(here it is on points, so if the IP address is of the following
format: "198.51.100.0", it will be split into 198 51 100 and 0).
Another parameter tells it which parts, of the string that it
has cut, it should take. Here it is parts 2 and 3. In the
example ip I gave above, this would give 51 and 100. A final
paramter tells it to put together the parts it has selected
(parts 2 and 3) with a new delimiter (here a slash). The result
would be 51/100. cut --delimiter=. --fields=2-3 --output-
delimiter=/ The result of all this (in my example being 51/100)
is saved inside the segments variable. Whenever you run the
following: whatever is between the backticks is executed. What
it returns is passed to the left side of the equals sign.