Auto-build OSX shell script watches directories, builds unless already building, using fswatch, stream_prettifier, and bash for Apportable 'dt' command line build

watch_and_dt.sh

#!/bin/bash
# DESCRIPTION: watch_and_dt.sh - watches a set of hardcoded directories and builds 
#  with Apportable dt unless already building.
# REAQUIREMENTS: Apportable dt, optionally stream_prettifier, fswatch, osx
# OPTIONAL: Run piping to stream_prettifier with ~/.stream_prettifier file
#  if_seen /Error|error/ do |line|
#      line.white.on_red
#  end
#  if_seen /Building.*apk/ do |line|
#      line.white.on_green
#  end
# OUTPUT (optionally colorized with stream_prettifier):
#  Mon Apr 27 17:31:20 PDT 2015 ( /Users/nick/proj/AdNetworkTests/adnetworktests/ViewController.m )
#  [7/7] Building Build/android-armeabi-debug/adnetworktests/adnetworktests-debug.apk
#  ...

# CONFIG 

DT_FULL_PATH=`which dt`
DT_BASE_PATH=${DT_FULL_PATH%/bin/dt}

WATCH_ME_0=.
WATCH_ME_1=$DT_BASE_PATH

IGNORE_ME_0=$DT_BASE_PATH/Build
IGNORE_ME_1=.git
IGNORE_ME_2=$DT_BASE_PATH/.git

export EXEC_CMD="dt 2>&1 | grep -i -e error -e Building.*apk"
export CMD_AS_SEEN_BY_PS_EF=$DT_FULL_PATH
export MAX_LINE_LENGTH=4096

# CODE

exec_unless() {
	num_running=$(ps -ef | grep -c $CMD_AS_SEEN_BY_PS_EF)
	if [ $num_running -gt 1 ]; then
		# Already running
		true
	else
		# Not running
		echo `date` \( $1 \) 
		bash -c "$EXEC_CMD" | cut -c 1-$MAX_LINE_LENGTH &
	fi
}

export -f exec_unless

fswatch -0 $WATCH_ME_0 $WATCH_ME_1 -e $IGNORE_ME_0 -e $IGNORE_ME_1 -e $IGNORE_ME_2 \
| xargs -0 -n 1 -I {} bash -c 'exec_unless "$@"' _ {}