Checks the status of network connections and stops / starts bittorrent sync based on that connectivity. In my case the network I don't want bit torrent sync running, it's first octet is 10.

btsync-check.sh

#!/bin/bash
IS_INTERNAL=0
IS_WIRELESS_CONNECTED=0
IS_WIRED_CONNECTED=0
IS_BTSYNC_RUNNING=0

PID_FILE=$HOME/.btsync.pid
LOG_FILE=$HOME/.btsync-check.log

TEST_WIRELESS=`ifconfig wlan0 | grep -i running`
TEST_WIRED=`ifconfig eth0 | grep -i running`
if [ -z "$TEST_WIRELESS" ];
then
  IS_WIRELESS_CONNECTED=0
else
  IS_WIRELESS_CONNECTED=1
fi

if [ -z "$TEST_WIRED" ];
then
  IS_WIRED_CONNECTED=0
else
  IS_WIRED_CONNECTED=1
fi

TEST_NETWORK=`ip addr | grep -iE "inet 10\..*(eth0|wlan0)"`
if [ -z "$TEST_NETWORK" ];
then
  IS_INTERNAL=0
else
  IS_INTERNAL=1
fi

if [ "$IS_INTERNAL" -eq 1 ];
then
  /usr/lib/btsync-user/btsync-stopper

  # remove the pid file
  if [ -f "$PID_FILE" ];
  then
    rm "$PID_FILE"
  fi
else
  # check to see if task is already running
  if [ -f "$PID_FILE" ];
  then
    # get current pid
    CURRENT_PID=$(<"$PID_FILE")

    #check if pid is running
    if [! ps -p ${CURRENT_PID} > /dev/null ];
    then
      /usr/lib/btsync-user/btsync-starter
    fi
  else
    /usr/lib/btsync-user/btsync-starter
  fi
fi

DATE=`date`
echo "${DATE} ${IS_INTERNAL} ${IS_WIRED_CONNECTED} ${IS_WIRELESS_CONNECTED}" >> $LOG_FILE