Learn Automating System Commands | System Interaction and Test Automation

Python can interact directly with your operating system to automate many tasks that would otherwise require manual input. Automating system commands allows you to check system status, start or stop services, and monitor resources without leaving your Python environment. This is especially useful for automation engineers who need to manage servers, deploy updates, or monitor critical infrastructure efficiently. By scripting these actions, you can ensure consistency, reduce human error, and save significant time during repetitive tasks.


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import os

# Run a simple system command and capture its output
command = "echo System automation is powerful!"
stream = os.popen(command)
output = stream.read()
print("Command output:", output.strip())

While the os module provides basic capabilities to run system commands, the subprocess module offers more advanced features and finer control. The subprocess.run function is commonly used to execute system commands, collect their output, and handle errors. This makes it ideal for automating tasks such as checking disk usage, verifying running services, or restarting network interfaces. By using subprocess.run, you can integrate system-level monitoring and control directly into your Python automation scripts, enabling more robust and flexible workflows.


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import subprocess

# Run the 'df -h' command to check disk space and capture output
result = subprocess.run(["df", "-h"], capture_output=True, text=True)
output = result.stdout

# Parse the output and make a decision based on disk usage
for line in output.splitlines():
    if line.startswith("/dev/"):
        parts = line.split()
        filesystem, size, used, available, percent, mountpoint = parts
        usage_percent = int(percent.strip('%'))
        if usage_percent > 80:
            print(f"Warning: {filesystem} is {usage_percent}% full!")
        else:
            print(f"{filesystem} usage is within safe limits ({usage_percent}%).")

1. Which Python module is commonly used to run system commands?

2. Why automate system commands in engineering?

3. Fill in the blank: 'subprocess.___(["ls", "-l"])' runs a system command.

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Section 3. Chapter 1

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