Wait until a process ends in PHP

PHP exec will wait until the execution of the called program is finished,
before processing the next line,
unless you use & at the end of the string to run the program in background.

#!/bin/bash
timestamp() {
  date +"%T"
}
pushd 'httpdocs/DIR1/DIR2'; 
file="Lock3.key"
if [ -f "$file" ]
then
    echo "$file found, Session is already in progress" $(date)
else
    echo "$file was not found, Its safe to start the script"  $(date)
    echo "Running Ebay Stock Only Script" $(date)
#Its possible to double check if the script is running by checking memory.
#ps aux | grep "php Cron-Run.php" (Not safe)
php Cron-Run.php > Output.log
echo "Finished Running Script, Lock file is deleted by PHP, Now exiting" $(date)
fi
exit