IT 117: Intermediate Scripting

IT 117: Intermediate Scripting
Homework 6

Due
What You Need to Do
Setup On Your Machine
Specification
Functions
Test Code
Output
Suggestions
Testing on Your Machine
Copy the Script to Unix
Testing the Script on Unix (Optional)

Due

Sunday, March 9th at 11:59 PM

What You Need to Do

Create the script hw6.py
Make sure it obeys the rules in Rules for Homework Scripts
Make sure the script has a hashbang line and is executable
Move it to an an hw6 directory on pe15.cs.umb.edu

Setup On Your Machine

Open a text editor.
I would suggest the text editor built into the program IDLE.
Save the file as hw6.py

Specification

This script has functions that use the os module
The script has three functions
- get_environment_variable_value()
- get_file_count()
- get_dir_count()

Functions

get_environment_variable_value()

The header for this function must be

def get_environment_variable_value(variable_name):

This function must accept a shell variable name as its only parameter
The function must return the value of this shell variable
If the variable is not defined, the function must return the empty string

get_file_count()

The header for this function must be
```
def get_file_count(dir_path):
```
This function must accept a directory name as a parameter
The function must return the number of files in this directory

get_dir_count()

The header for this function must be
```
def get_dir_count(dir_path):
```
This function must accept a directory name as a parameter
The function must return the number of directories inside this directory

Test Code

Your script must contain the following statements

They should appear at the bottom of your script

path_value = get_environment_variable_value("SHELL")
if path_value:
    print(path_value)
file_count = get_file_count("/")
if file_count:
    print(file_count)
dir_count = get_dir_count("/")
if dir_count:
	print(dir_count)

Output

When run on pe15.cs.umb.edu the output should look like this
```
/bin/bash
3
33
```
The output on your machine should be broadly similar

Suggestions

Write this script in stages
Test your script at each step
Print the steps below
And check them off as you finish each one

Create the file hw6.py and in it add the headers for all functions.
The body of each function should be the Python statement pass.
There must be a blank line between each function.
Add the test code below.
There must be a blank line between the functions and the test code.
Run the script.
You should see nothing.
Fix any errors you find.
Under the hashbang line write a statement to import the os module.
Remove the pass statement from get_environment_variable_value.
There is a variable in the os module that allows you to find the value of any shell variable.
Get the value of the shell variable whose name is given by the parameter variable_name and store it in the variable value.
Add a statement to print value.
Run the script.
You should see the value of your SHELL variable.
Fix any errors you find.
Remove the print statement and replace it with a statement that returns value.
Run the script.
You should see the value of your SHELL variable.
Fix any errors you find.
Remove the pass statement from get_file_count.
Add a statement that prints the value of the parameter dir_path.
Run the script.
You should see / on a line under the value of your SHELL variable.
Fix any errors you find.
Remove the print statement.
Replace it with an assignment statement that sets count to 0.
Now to the os function that changes to a new directory using the parameter dir_path as the argument.
Run the os function that returns a list of the entries in a directory in the current directory and store this in the variable entries.
Print entries.
Run the script.
Fix any errors you find.
Remove the print statement.
Replace it with a for loop over entries using the loop variable entry.
Inside the loop print entry.
Run the script.
Fix any errors you find.
Remove the print statement.
In it's place write an if statement that will run if entry is a file.
There is a boolean funtion in os.path that will return True if it's argument is the name of a file.
Use this funtion in the if header.
In the cofde block for this if statement print entry.
Run the script.
Fix any errors you find.
Inside the if statement, remove the call to print.
Replace it with a statement that increments the value of count by 1.
Out side the for loop, print count.
Run the script.
Fix any errors you find.
Replace the print statement you just wrote with a statement that returns the value of count.
Run the script.
It should print out the same number as in the previous step. Fix any errors you find.
Remove the pass statement from print_file_count_for_dir_list.
Replace it with the code block from get_file_count().
Run the script.
Fix any errors you find.
You need to change the function used in the if statement.
There is a boolean funtion in os.path that will return True if its argument is the name of a directory.
You must use this function in the if statement.
Run the script.
Fix any errors you find.

Copy the file to Unix

Open FileZilla and connect to pe15.cs.umb.edu
You will have to connect using your Unix username and password.
Go to your it117 directory
Go to your hw directory
Create a directory for this exercise
Right-click in the whitespace and create the hw6 directory
Copy the script to the to hw6
Click and drag the file from the bottom left panel to the bottom right panel
Make the script executable
Right-click on the file and select "Permissions" from the menu
Enter 755 in the box provided

Testing on Your Machine

Open IDLE
Use the Open command in IDLE to open hw6.py
Under the Run menu, select Run Module

When run on pe15.cs.umb.edu the output should look like this

/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
3
33

The output on your machine should be broadly similar

Copy the Script to Unix

Open FileZilla and connect to pe15.cs.umb.edu
Go to your it117 directory
Go to your hw directory
Right-click in the whitespace inside the hw directory
Enter hw6 in the dialog box
Click and drag your script from the bottom left panel to the bottom right panel
Right-click on the file and select "Permissions" from the menu
Enter 755 in the box provided
This will make the script executable

Testing the Script on Unix (Optional)

Connect to pe15.cs.umb.edu using an ssh client like putty.exe (Windows) or ssh (Mac)
Go to the directory for this exercise
```
cd  it117/hw/hw6
```
Run this script
```
python3 hw6.py
```
You should see something like this
```
/bin/bash
3
33
```