Process management (running programs) in Intro to Computing - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a new process in Python using the subprocess module.

Intro to Computing

import subprocess
subprocess.[1](['echo', 'Hello World'])

Drag options to blanks, or click blank then click option'

Alaunch

Brun

Cexecute

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'start' instead of 'run' causes an AttributeError.

Using 'execute' or 'launch' are not valid subprocess functions.

The subprocess.run() function is used to run a command in a new process and wait for it to complete.

2fill in blank

medium

Complete the code to create a new process that runs a Python script asynchronously.

Intro to Computing

import subprocess
process = subprocess.[1](['python3', 'script.py'])

Drag options to blanks, or click blank then click option'

Aexecute

Brun

Ccall

DPopen

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'run' waits for the process to finish.

Using 'call' is similar to 'run' and waits.

subprocess.Popen() starts a process asynchronously, allowing the program to continue without waiting.

3fill in blank

hard

Fix the error in the code that tries to terminate a running process.

Intro to Computing

import subprocess
proc = subprocess.Popen(['sleep', '10'])
proc.[1]()

Drag options to blanks, or click blank then click option'

Aterminate

Bend

Ckillall

Dstop

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'stop' or 'end' causes AttributeError.

Using 'killall' is not a method of Popen objects.

The terminate() method sends a signal to stop the process gracefully.

4fill in blank

hard

Fill both blanks to check if a process has finished and get its exit code.

Intro to Computing

import subprocess
proc = subprocess.Popen(['ls'])
if proc.[1]() is not None:
    exit_code = proc.[2]

Drag options to blanks, or click blank then click option'

Apoll

Bwait

Creturncode

Dexit

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'wait' in first blank blocks until process ends.

Using 'exit' is not a valid attribute or method.

poll() checks if the process has finished without waiting, returning None if still running.

returncode gives the exit status of the process after it finishes.

5fill in blank

hard

Fill all three blanks to start a process, wait for it to finish, and capture its output.

Intro to Computing

import subprocess
result = subprocess.[1](['echo', 'Hello'], capture_output=[2], text=[3])
print(result.stdout)

Drag options to blanks, or click blank then click option'

Arun

BTrue

CFalse

DPopen

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Popen' does not capture output by default.

Setting capture_output or text to False returns bytes or no output.

subprocess.run() runs the command and waits for it to finish.

Setting capture_output=True captures the output.

Setting text=True returns output as a string instead of bytes.

Practice

1. What is a process in computing?

easy

A. A user account on the computer

B. A program that is currently running on a computer

C. A type of computer hardware

D. A file stored on the hard drive

Solution

1. Step 1: Understand the term 'process'

   A process is an instance of a program that is executing or running on a computer.

2. Step 2: Differentiate from other options

   Files, hardware, and user accounts are not running programs, so they are not processes.

3. Final Answer:

   A program that is currently running on a computer -> Option B

4. Quick Check:

   Process = Running program [OK]

Hint: Process means a running program, not a file or hardware [OK]

Common Mistakes:

• Confusing process with a file
• Thinking process is hardware
• Mixing process with user account

2. Which of the following commands correctly starts a program named app.exe on a Windows system?

easy

A. start app.exe

B. run app.exe

C. execute app.exe

D. launch app.exe

Solution

1. Step 1: Identify the correct Windows command

   On Windows, the command to start a program from the command line is start.

2. Step 2: Check other options

   Commands like run, execute, and launch are not valid Windows commands to start programs.

3. Final Answer:

   start app.exe -> Option A

4. Quick Check:

   Windows uses 'start' to run programs [OK]

Hint: Windows command to run programs is 'start' [OK]

Common Mistakes:

• Using 'run' instead of 'start'
• Confusing with Linux commands
• Assuming 'launch' is a command

3. Consider this flowchart for running a program:

What is the correct order of steps when a computer runs a program?

medium

A. Start -> Load program -> Execute program -> End

B. Execute program -> Load program -> Start -> End

C. Load program -> Start -> Execute program -> End

D. Start -> Execute program -> Load program -> End

Solution

1. Step 1: Analyze the flowchart steps

   The flowchart shows the process begins with 'Start', then 'Load program', followed by 'Execute program', and finally 'End'.

2. Step 2: Match the correct sequence

   Start -> Load program -> Execute program -> End matches the exact order shown in the flowchart.

3. Final Answer:

   Start -> Load program -> Execute program -> End -> Option A

4. Quick Check:

   Program runs: Start, Load, Execute, End [OK]

Hint: Follow flowchart arrows from start to end [OK]

Common Mistakes:

• Mixing order of loading and executing
• Starting execution before loading
• Ignoring the start and end steps

4. A user tries to run a program but gets an error: 'Process not found'. What is the most likely cause?

medium

A. The user has too many programs open

B. The computer hardware is broken

C. The program file does not exist or path is wrong

D. The program is already running

Solution

1. Step 1: Understand the error message

   'Process not found' means the system cannot locate the program to start it.

2. Step 2: Identify the cause

   This usually happens if the program file is missing or the path to it is incorrect.

3. Final Answer:

   The program file does not exist or path is wrong -> Option C

4. Quick Check:

   Missing file or wrong path causes 'Process not found' [OK]

Hint: Check file existence and path if process not found error occurs [OK]

Common Mistakes:

• Assuming hardware failure causes this error
• Thinking too many programs cause 'process not found'
• Believing program already running causes this error

5. You want to run two programs at the same time on your computer. Which process management feature allows this?

hard

A. Data encryption

B. File compression

C. Disk defragmentation

D. Multitasking

Solution

1. Step 1: Understand running multiple programs

   Running two programs simultaneously requires the computer to manage multiple processes at once.

2. Step 2: Identify the feature

   This feature is called multitasking, which allows the operating system to switch between processes quickly.

3. Final Answer:

   Multitasking -> Option D

4. Quick Check:

   Multitasking = Running multiple programs simultaneously [OK]

Hint: Multitasking lets you run many programs at once [OK]

Common Mistakes:

• Confusing multitasking with file compression
• Thinking disk defragmentation runs programs
• Mixing data encryption with process management