[ssh] Cleaning up shells and ssh configurablility when not at home

bin/.bin/onsubnet

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+if [[ "$1" == "--help" ]] || [[ "$1" == "-h" ]]  || [[ "$1" == "" ]] ; then
+  printf "Usage:\n\tonsubnet [ --not ] partial-ip-address\n\n"
+  printf "Example:\n\tonsubnet 10.10.\n\tonsubnet --not 192.168.0.\n\n"
+  printf "Note:\n\tThe partial-ip-address must match starting at the first\n"
+  printf "\tcharacter of the ip-address, therefore the first example\n"
+  printf "\tabove will match 10.10.10.1 but not 110.10.10.1\n"
+  exit 0
+fi
+
+on=0
+off=1
+if [[ "$1" == "--not" ]] ; then
+  shift
+  on=1
+  off=0
+fi
+
+regexp="^$(sed 's/\./\\./g' <<<"$1")"
+
+if [[ "$(uname)" == "Darwin" ]] ; then
+  ifconfig | grep -F 'inet ' | grep -Fv 127.0.0. | cut -d ' ' -f 2 | grep $1
+else
+  hostname -I | tr -s " " "\012" | grep -Fv 127.0.0. | grep $1
+fi
+
+if [[ $? == 0 ]]; then 
+  exit $on
+else
+  exit $off
+fi
+