October 13, 2024

Python Tutorials

Python sys module

The sys module in Python provides access to some variables used or maintained by the Python interpreter and to functions that interact strongly with the interpreter. It allows you to manipulate the Python runtime environment and perform various system-level operations.

1. Importing the sys Module

To use the functions and variables provided by the sys module, you need to import it first:

import sys

2. Command-Line Arguments

The sys.argv list contains the command-line arguments passed to the script. The first element, sys.argv[0], is the name of the script, and the subsequent elements are the arguments.

import sys

# Print the name of the script
print("Script name:", sys.argv[0])

# Print the command-line arguments
print("Arguments:", sys.argv[1:])

3. Exiting the Program

The sys.exit() function allows you to exit the program. You can optionally pass an exit status code. A status code of 0 indicates success, while any non-zero value indicates an error.

import sys

# Exit the program with a status code of 0
sys.exit(0)

4. Standard Input, Output, and Error

The sys module provides file objects for standard input, output, and error streams:

  • sys.stdin: Standard input stream (usually the keyboard).
  • sys.stdout: Standard output stream (usually the console).
  • sys.stderr: Standard error stream (usually the console, used for error messages).
import sys

# Print to standard output
sys.stdout.write("Hello, World!\n")

# Print an error message to standard error
sys.stderr.write("Error: Something went wrong.\n")

5. sys.path

The sys.path list contains the directories that the Python interpreter searches for modules. You can modify this list to add or remove directories where Python looks for modules.

import sys

# Print the current Python path
print("Python Path:", sys.path)

# Add a new directory to the Python path
sys.path.append('/path/to/directory')
print("Updated Python Path:", sys.path)

6. sys.platform

The sys.platform string provides a platform identifier that can be used to check the operating system on which Python is running.

import sys

# Check the platform
print("Platform:", sys.platform)

7. sys.version

The sys.version string provides information about the Python version in use, including the version number and build information.

import sys

# Print the Python version
print("Python Version:", sys.version)

8. sys.getsizeof()

The sys.getsizeof() function returns the size of an object in bytes. This can be useful for memory management and optimization.

import sys

# Calculate the size of an integer
size = sys.getsizeof(100)
print("Size of 100:", size, "bytes")

# Calculate the size of a list
size = sys.getsizeof([1, 2, 3, 4, 5])
print("Size of list:", size, "bytes")

9. sys.modules

The sys.modules dictionary contains all the modules that have been imported. You can use it to check if a module is loaded or to reload a module.

import sys

# Check if a module is loaded
if 'os' in sys.modules:
    print("The 'os' module is loaded")

# List all loaded modules
print("Loaded Modules:", sys.modules.keys())

10. sys.maxsize

The sys.maxsize attribute provides the largest positive integer that a Python int can represent. This is useful for understanding the limits of integer operations on your platform.

import sys

# Print the maximum size of an integer
print("Maximum Integer Size:", sys.maxsize)

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