You want a Perl program to call a Python program to call a Ruby program to call another Python program. You are using Linux as the OS.
Here is a one-line Perl program (course.pl) that calls a Python program:
system( "python /home/ec2-user/cont.py");
Here is a two-line Python program named cont.py. It invokes a Ruby program.
subprocess.call(['ruby /home/ec2-user/integration.rb'], shell=True)
Here is a one-line Ruby script file named integration.rb (that calls a Python script).
exec( "python /home/ec2-user/new.py" )
Here is a one-line Python program that prints a basic message, name it "new.py":
print "This final Python script worked!!!"
If each of the above four programs (course.pl, cont.py, integration.rb, new.py) are all in the /home/ec2-user/ directory, just run the Python program like this: perl course.pl
It will print "This final Python script worked!!!" This demonstrates integration of three languages with four files and five lines of code.