Launching Other Programs from Python Interpreter

LOP.txt

#### Launching other programs using python

You can launch other program using `Popen()` function present in built in `subprocess()` module.
To start an external progra, from your python script,pass filename to subprocess.Popen()

For example 
```
>>> import subprocess
>>> subprocess.Popen('C:\\Windows\\System32\\calc.exe')
```
Popen has two useful methods 
```
poll() - The poll() method will return None if the process is still running at the time poll() is called. If the program has
terminated, it will return the process’s integer exit code.
wait() - The wait() method is like waiting for your friend to finish working on his/her code before you keep working on yours.
```

You can also pass command line arguments to Popen()
For example
```
subprocess.Popen(['C:\\Windows\\notepad.exe', 'C:\\hello.txt'])
```
This will not only launch the Notepad application but also have it
immediately open the C:\hello.txt file.