ID a card/port pair, given a simple serial jack number

We recently installed a really nice Foundry switch (highly recommended) and its admin (as is generally the case) requires addressing ports by the combination of card and port number. However the cables jacking into it are numbered serially; from 1 to whatever.

So when you need to find which cart/port corresponds to which jack, it can get messy - here's a simple script (easily adapted to other scenarios) to simplify:

#!/bin/bash

# simple script to calc the card/port pair, given the patch cable #
# - result is returned as an integer, in format: port + (100 * card#)

# History:
#
# 20070523 mvgfr: incep

# minimal error trapping:
if [ -z "$1" ] ; then exit 0; fi
if [ "$1" -le 0 ] ; then exit 0; fi

patch=$1
# fudge for discountinuity; jump from card #8 to #13 (since there are no port cards in slots 9-12)
if [ "$patch" -gt 192 ] ; then let patch+=96 ; fi

card=$(( ( ( $patch * 100 / 24 ) + 99 ) / 100 ))
port=$(( $patch - ( ( $card - 1 ) * 24 ) ))

echo "$card, $port"

result=$(( ( $card * 100 ) + $port))
echo $result

exit $result #send the result back as the exit code, for potential further processing...

#end