Run processes while you do not touch your Mac.

darwinbg

#!/bin/bash
# -*- coding: utf-8 -*-

export PATH=/usr/local/bin:/usr/local/sbin/:/usr/bin/:/usr/sbin/:/bin/:/sbin/

## Avoid reentrance.
exec 9< $0
perl -mFcntl=:flock -e "open(LOCK,'<&=9');exit(!flock(LOCK,LOCK_EX|LOCK_NB))" || exit 0

## Exit for error or undefined.
set -eu

idlethresh=$((60 * 5))
checkinterval=10
# idlethresh=5
# checkinterval=5
## Do not start nor continue with these SSIDs.
badssids=("Too Slow", "Too Expensive")
## Do not start nor continue with these network services.
badnwsvcs=("Bluetooth PAN")

contains () {
  local e
  for e in "${@:2}"
  do
    test "$e" == "$1" && return 0
  done
  return 1
}

function badnetworkp() {
  local ssid
  local badnwsvc
  ssid=$(/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I | sed -n -e "s/^ *SSID: //p")
  if test -n "$ssid" && contains "$ssid" "${badssids[@]}"
  then
    echo "Bad Wi-Fi is active."
    return 0
  fi
  for badnwsvc in "${badnwsvcs[@]}"
  do
    if test -n "$(/usr/sbin/networksetup -getinfo "Bluetooth PAN" | sed -ne s/"^IP address: //p")"
    then
      echo "Bad network service is active."
      return 0
    fi
  done
  return 1
}

if badnetworkp
then
  echo "Network connection is bad one. Exiting."
  exit 0
fi

: ${FORCE:=""}

## Get UI idle time in second.
function idlesec() {
  test -n "$FORCE" && echo 86400 && return
  echo $(($(ioreg -c IOHIDSystem | grep HIDIdleTime | head -n 1 | sed 's/.* = //') / 1000000000))
}

## Stop for a while if UI is recently used.
echo Waiting.
while :
do
  test "$(idlesec)" -ge "$idlethresh" && break
  sleep $checkinterval
done

## Get child process IDs.
function children() {
  for pid in $(pgrep -P $1)
  do
    echo $pid
    children $pid
  done
}

## Send signal to all child processes.
function killtree() {
  kill -s $1 $pid $(children $2) && :
}

## Absolute path of this script.
self="$(p="$0";while :;do t="$(readlink "$p")";cd "$(dirname "$p")";test -z "$t"&&break||p="$t";done;echo "$(pwd -P)/$(basename "$p")")"

pid=

function onexit() {
  trap "" SIGTERM # Ignore
  kill -- -$$ && : # Not option but process group
  ## command line - What is a stopped process in linux? - Super User http://superuser.com/questions/403200/what-is-a-stopped-process-in-linux
  kill -CONT -- -$$ && :
}

# function onexit() {
#   test -n "$pid" && killtree TERM "$pid" || :
# }

trap onexit SIGINT SIGTERM EXIT

## Run all the executables under $self.d/ sequently.
for file in $self.d/*
do
  base=$(basename "$file")
  test "${base:0:1}" = "_" && continue
  echo "$base" | grep -q -e "~" -e "#" && continue
  $file &
  pid=$!
  while :
  do
    if badnetworkp
    then
      echo Network connection has been changed to bad one. Exiting.
      killtree TERM $pid
      wait
      exit 0
    fi
    stat="$(ps auxww $pid | tail -n +2 | awk '{print $8}' | sed -e 's/\(.\).*/\1/')"
    test -z "$stat" && pid="" && break
    case $stat in
      R | S | D ) # Running
        if test "$(idlesec)" -lt "$idlethresh"
        then
          killtree STOP $pid
          echo "Stopped subprocess(es)."
        fi
        ;;
      T ) # Stopped
        if test "$(idlesec)" -ge "$idlethresh"
        then
          killtree CONT $pid
          echo "Restarted subprocess(es)."
        fi
        ;;
    esac
    sleep $checkinterval
  done
done