Menu driven BASH script for accessing CTA Bus Tracker, http://www.ctabustracker.com/bustime/eta/eta.jsp. Also have the option to manually enter the bus stop number to get arrival times. ./CTABusTracker.sh -r <Route Number> -s <Stop ID>

CTABusTracker.sh

## Filename: CTABusTracker.sh
## Author: Joel Fernandez
## Date:
## Description: Command Line Utility for CTA's Bus Tracker
main()
{
	##############################
	## Internal Field Separator ##
	##############################
	SAVEIFS=$IFS
	IFS=$(echo -en "\n\b")
	######################
	## Global Variables ##
	######################

	## CTA Bus Tracker ## API Key
	Key="key=Pt2xR9LVfGhUgmVgiJr25PiMR"

	## CTA Bus Tracker ## Base URLs
	TimeURL="http://www.ctabustracker.com/bustime/api/v1/gettime?"
	VehiclesURL="http://www.ctabustracker.com/bustime/api/v1/getvehicles?"
	PatternsURL="http://www.ctabustracker.com/bustime/api/v1/getpatterns?"
	ServiceBulletinsURL="http://www.ctabustracker.com/bustime/api/v1/getservicebulletins?"
	RoutesURL="http://www.ctabustracker.com/bustime/api/v1/getroutes?"
	DirectionsURL="http://www.ctabustracker.com/bustime/api/v1/getdirections?"
	StopsURL="http://www.ctabustracker.com/bustime/api/v1/getstops?"
	PredictionsURL="http://www.ctabustracker.com/bustime/api/v1/getpredictions?"

	while getopts “hr:s:” OPTION
	do
	     case $OPTION in
	 		h)
	             	usage
	             	exit 1
	             	;;
	        r)
	             	RT=$OPTARG
	             	;;
	        s)
	             	STPID=$OPTARG
	             	;;
	        ?)
	             	routes
					directions
					stops
					predictions
					;;
	     esac
	done	
	
	if [[ $RT ]] || [[ $STPID ]]; then
		predictionsCLI
	else
		routes
		directions
		stops
		predictions
	fi
}
usage()
{
clear;
cat << EOF
Menu driven and command line BASH script for accessing CTAs Bus Tracker, 
http://www.ctabustracker.com/bustime/eta/eta.jsp.  

OPTIONS: 
	-h	Help 
   	-r	Route Number 
   	-s	Stop ID 

To get arrival times for the North Ave & Milwaukee/Damen (Blue Line) bus stop, 
enter the following at the command line. 

        Route Number__       __Stop ID 
                      |      | 
                      |      | 
                      |      | 
./CTABusTracker.sh -r 72 -s 945 

To access the CTA Bus Tracker Menu. Just launch the script without any arguments.
EOF
}
##
## Function: XML2ARRAY
## Accepts Input From Xpath Query's And Inserts Carriage Return 
## Between XML Nodes In Order To Save The Query Results As An Array
##
XML2ARRAY()
{
	sed 's/></\
		</g' | cut -f2 -d">" | cut -f1 -d"<"
}
###############################################################################
## Function: routes()
## Get List Of Available Bus Routes And Displays It On The Screen.
## The Bus Route Selection Is Passed To The directions() Function.
###############################################################################
routes()
{
	routesURL;
	routesVariables;
	clear;
	routesMenu | column;
	routesSelection;
}
##
## Function: routesURL()
## Construct Routes URL, Save HTML Page.
##
routesURL()
{
	html=$(curl -s $RoutesURL$Key);
}
##
## Function: routesVariables()
## Scrapes The routesURL For Route Numbers And Corresponding
## Route Names.
##
routesVariables()
{
	routeCount=$(echo "$html" | xpath 'count(/bustime-response/route)' 2> /dev/null);
	rt=( $(echo "$html" | xpath //rt 2> /dev/null | stopsAMP | XML2ARRAY) );
	rtnm=( $(echo "$html" | xpath //rtnm 2> /dev/null | stopsAMP | XML2ARRAY) );
}
##
## Function: routesMenu()
## Menu That Displays A List Of All Available Bus Routes.
## Accepts Input From routesVariables() Function.
##
routesMenu()
{
	for ((i=0;i<${#rt[@]};i++));do
		## Add Numerals To The Bus Route Menu
		printf "%5s%-40s\n" "${rt[i]}) " \
			"${rtnm[i]}"
	done
}
##
## Function: routesSelection()
## Accepts User Input And Captures The Bus Route Selection.
##
routesSelection()
{
	echo;
	echo;
	echo;
	echo;
	read -p "PLEASE SELECT THE BUS ROUTE: " REPLY1;
	echo;
	echo;
}
###############################################################################
## Function: directions()
## Displays The Direction The Bus Routes Goes.
## The Direction Selection Is Passed Along To The stops() Function.
###############################################################################
directions()
{
	clear;
	for ((n=0;n<$routeCount;n++)); do
		if [ ${rt[n]} = $REPLY1 ]; then
			directionsURL;
			directionsVariables;
			directionsMenu | column;
			directionsSelection;
		fi;
	done;

}
##
## Function: directionsURL()
## Construct Directions URL, Save HTML Page.
##
directionsURL()
{
	html=$( curl -s $DirectionsURL$Key"&rt=""$REPLY1");
}
##
## Function: directionsVariables()
## Scraps The directionsURL For The Direcrections For Each Bus Route.
## Accepts Input From The routesSelection() Function.
##
directionsVariables()
{
	dir=( $( echo "$html" | xpath //dir 2> /dev/null | XML2ARRAY) );
}
##
## Function: directionsMenu()
## Menu That Displays The Directions A Bus Rout Travels.
## Accepts Input From directionsVariables() Function.
##
directionsMenu()
{
	for ((i=0;i<${#dir[@]};i++));do
		## Add Numerals To The Bus Direction Menu
		printf "%5s%-40s\n" "$(($i+1))) " \
			"${dir[i]}"
	done;
}
##
## Function: directionsSelection()
## Accepts User Input And Captures The Bus Direction Selection.
##
directionsSelection()
{
	echo;
	echo;
	echo;
	echo;
	read -p "PLEASE SELECT THE BUSES DIRECTION: " REPLY2;
	echo;
	echo;
}
###############################################################################
## Function: stops()
## Displays The Bus Stops.
## The Bus Stop Selection Is Captured and Passed Along To The 
## predictions() Function.
###############################################################################
stops()
{

	for ((n=1;n<=${#dir[@]};n++));do
		if [ $REPLY2 = $n ];then
			stopsURL;
			stopsVariables
			echo;
			echo;
			clear;
			stopsMenu | column;
			stopsReply;
		fi;
	done;
}
##
## Function: stopsURL()
## Construct Stops URL, Save HTML Page.
##
stopsURL()
{
	html=$( curl -s $StopsURL$Key"&rt=""$REPLY1""&dir="$(echo ${dir[$REPLY2-1]} | stopsTWENTY));
}
##
## Function: stopsVariables()
## Scrapes The stopsURL For The Bus Stop And Number.
## Accepts Input From The directionsSelection() Function.
##
stopsVariables()
{
	stpnm=( $( echo "$html" | xpath //stpnm 2> /dev/null | XML2ARRAY) );
	stpid=( $( echo "$html" | xpath //stpid 2> /dev/null | XML2ARRAY) );
}
##
## Function: stopsMenu()
## Menu That Displays The Stop Names For Each Bus Route.
## Accepts Input From The stopsVariables() Function.
##
stopsMenu()
{
	for ((i=0;i<${#stpnm[@]};i++));do
		## Add Numerals To The Bus Direction Menu
		printf "%5s%-40s\n" "$(($i+1))) " \
			"${stpnm[i]}" | stopsAMP;
	done;
}
##
## Function: stopsReply
## Accepts User Input And Captures The Bus Stop Selection.
##
stopsReply()
{
	echo;
	echo;
	echo;
	echo;
	read -p "PLEASE SELECT THE BUS STOP: " REPLY3;
	echo;
	echo;
}
##
## Function: stopsAMP()
## Quick And Dirty sed Command To Remove "&amp;" From The stpnm Variable
## In Order For The Bus Stop Name To Be Displayed Properly On The routesMenu(), 
## predictionsHeader () and predictionsNoHeader() Functions
##
stopsAMP()
{
	sed 's/amp;//g';
}
##
## Function: stopsTWENTY()
## Quick And Dirty sed Command To Add "%20" To The dir Variable To Help
## Construct URLs For The stopVariables() And predictionsNoHeader() Functions.
##
stopsTWENTY()
{
	## Add "%20" To StopURL Variable
	sed 's/ /%20/g';
}
###############################################################################
## Function: predictions()
## Displays The Predicted Arrival Time For The Bus Stop.
###############################################################################
predictions()
{
	for ((n=1;n<=${#stpid[@]};n++));do
		if [ $REPLY3 = $n ];then
			predictionsURL;
			predictionsVariables;
		fi;
	done;
	if [ "$msg" = "No service scheduled" ];then
		clear;
		predictionsNoHeader;
		predictionsNoServiceScheduled;
	elif [ $prd = 0 ];then
		clear;
		predictionsNoHeader;
		predictionsNoArrivalTimes;
	else
		clear;
		predictionsHeader;
		for ((i=0;i<"$prd";i++));do
			predictionsSchedule;
		done;
		predictionsMargin
	fi;
}
###############################################################################
## Function: predictionsCLI()
## Displays The Predicted Arrival Time For The Bus Stop From Command
## Line Argument.
###############################################################################
predictionsCLI()
{
	predictionsCLIURL;
	predictionsVariables;
	if [ "$msg" = "No service scheduled" ];then
		clear;
		predictionsNoHeader;
		predictionsNoServiceScheduled;
	elif [ $prd = 0 ];then
		clear;
		predictionsNoHeader;
		predictionsNoArrivalTimes;
	else
		clear;
		predictionsHeader;
		for ((i=0;i<"$prd";i++));do
			predictionsSchedule;
		done;
		predictionsMargin
	fi;
}
##
## Function: predictionsEPOCH()
## Converts tmpstmp and prdtm Variables To An EPOCH Value.
## Used To Help Calculate The Predicted Arrival Time.
##
predictionsEPOCH()
{
	min=$(( 60 ));
	hr=$(( 60*60 ));
	day=$(( 60*60*24 ));
	month=$(( (60*60*24)*(365/12) ));
	year=$(( 60*60*24*365 ));
	sed 's/\([0-9][0-9][0-9][0-9]\)\([0-9][0-9]\)\([0-9][0-9]\)/\1 \2 \3/g' | \
		sed 's/:/ /g' | \
		awk '{ print ($1 * '$year') + ($2 * '$month') + ($3 * '$day') + \
		($4 * '$hr') + ($5 * '$min') }';
}
##
## Function: predictionsURL()
## Construct Predictions URL, Save HTML Page.
##
predictionsURL()
{
	html=$( curl -s $PredictionsURL$Key"&rt=""$REPLY1""&stpid="${stpid[n-1]});
}
##
## Function: predictionsCLIURL()
## Construct Predictions URL From Command Line Arguments, Save HTML Page.
##
predictionsCLIURL()
{
	html=$( curl -s $PredictionsURL$Key"&rt="$RT"&stpid="$STPID);
}
##
## Function: predictionsVariables()
## Scrapes The predictionsURL For A Bunch Of Variables
##
predictionsVariables()
{
	prd=$( echo "$html" | \
		xpath 'count(//stpnm)' 2> /dev/null);
	if [ $prd -ge 5 ];then
		prd=5;
	fi;
	margin=$(( 5 - $prd ));
	error=( $( echo "$html" | \
		grep "<error>" | \
		wc -l) );
	msg=( $( echo "$html" | \
		xpath //msg 2> /dev/null | \
		XML2ARRAY) );
	tmstmp=( $( echo "$html" | \
		xpath //tmstmp 2> /dev/null | \
		XML2ARRAY | \
		predictionsEPOCH) );
	typ=( $( echo "$html" | \
		xpath //msg 2> /dev/null | \
		XML2ARRAY) );
	stpid=( $( echo "$html" | \
		xpath //stpid 2> /dev/null | \
		XML2ARRAY) );
	stpnm=( $( echo "$html" | \
		xpath //stpnm 2> /dev/null | \
		XML2ARRAY | \
		stopsAMP) );
	vid=( $( echo "$html" | \
		xpath //vid 2> /dev/null | \
		XML2ARRAY) );
	dstp=( $( echo "$html" | \
		xpath //dstp 2> /dev/null | \
		XML2ARRAY) );
	rt=( $( echo "$html" | \
		xpath //rt 2> /dev/null | \
		XML2ARRAY) );
	rtdir=( $( echo "$html" | \
		xpath //rtdir 2> /dev/null | \
		XML2ARRAY) );
	des=( $( echo "$html" | \
		xpath //des 2> /dev/null | \
		XML2ARRAY | \
		sed 's/ Blue Line//g') );
	prdtm=$( echo "$html" | \
		xpath //prdtm 2> /dev/null | \
		XML2ARRAY | \
		predictionsEPOCH);
	dly=( $( echo "$html" | \
		xpath //dly 2> /dev/null | \
		XML2ARRAY) );
	arrival=( $(echo "$prdtm" | \
		awk '{ print ( ( $1 - '$tmstmp' ) / 60 ) }') );
		
}
predictionsNoHeader()
{
	rtdir=( $( curl -s $DirectionsURL$Key"&rt="${rt[$REPLY1-1]} | \
		xpath //dir 2> /dev/null | \
		XML2ARRAY) );
	for n in ${rtdir[@]};do
		stpnm=$(curl -s $StopsURL$Key"&rt="${rt[$REPLY1-1]}"&dir="$(echo $n | stopsTWENTY) | \
			xpath //stop[stpid=$stpid] | \
			xpath //stpnm 2> /dev/null | \
			XML2ARRAY | \
			stopsAMP);
		if [ "$stpnm" != "" ];then
			clear;
			printf "%2s%38s\n" "${rt[$REPLY1-1]}" "$stpnm";
			printf "%40s\n" "$rtdir";
		fi;
	done;
}
predictionsNoServiceScheduled()
{
	title="NO SERVICE IS SCHEDULED";
	COLUMNS=40;printf "%*s\n" $(((${#title}+$COLUMNS)/2)) "$title";
	echo;
	echo;
	echo;
	echo;
}
predictionsNoArrivalTimes()
{
	title="NO ARRIVAL TIMES SCHEDULED";
	COLUMNS=40;printf "%*s\n" $(((${#title}+$COLUMNS)/2)) "$title";
	echo;
	echo;
	echo;
	echo;
}
predictionsHeader()
{
	printf "%2s%38s\n" "$rt" "$stpnm";
	printf "%40s\n" "$rtdir";
}
predictionsSchedule()
{
	COL1="BUS ${vid[i]}";
	COL3="${des[i]}";
	COL5=$(
	if [ "${dly[i]}" = "true" ];then
		echo "DELAYED"
	elif [ ${arrival[i]} -le 1 ];then
		echo "APPROACHING";
	else
		echo "${arrival[i]} MIN";
	fi);
	width=40;
	width1=$( echo $COL1 | \
		wc -c);
	width3=$( echo $COL3 | \
		wc -c);
	width5=$( echo $COL5 | \
		wc -c);
	width2=$(( ($width - $width1 - $width3 - $width5) / 2 ));
	width4=$(( $width - $width1 - $width2 - $width3 - $width5 ));
	printf "%-${width1}s%${width2}s%${width3}s%${width4}s%${width5}s\n" "$COL1" "" "$COL3" "" "$COL5";
}
predictionsMargin()
{
	for ((i=0;i<$margin;i++)); do
		echo
	done
}
main $@