Function exec( cmd, arg1, arg2 )

Description:
Executes an operating system command with two arguments.
Parameters:
cmd (String)
name of command
arg1 (String)
the first argument
arg2 (String)
the second argument
Return Value (String):
short log message
Example:
exec("do_stuff.py", toString(RA), toString(DEC))
Signature:
String exec(String, String, String)