Python shell scripts list
Python shell scripts list
I apologize for the confusion earlier! Here's a comprehensive list of Python shell scripting examples:
Basic Commands
print("Hello, World!") - Displays "Hello, World!" on the screen. input() - Reads user input and stores it in a variable. int(input()) - Reads an integer from user input and converts it to an integer.
File Input/Output Operations
open("file.txt", "r").read() - Reads contents of a file named "file.txt" and displays it. open("file.txt", "w").write("Hello, World!") - Writes "Hello, World!" to a new or existing file named "file.txt".
with open("file.txt", "a") as f: f.write("This is an append operation.") - Appends text to the end of a file named "file.txt".
Control Flow Statements
if x > 5: print("x is greater than 5") - Checks if a variable x is greater than 5 and prints a message. for i in range(10): print(i) - Prints numbers from 0 to 9 using a for loop. while True: input() - Enters an infinite loop where it waits for user input.
Functions
def greet(name): print("Hello, " + name + "!") - Defines a function that takes a name as argument and prints a greeting message. greet("John") - Calls the greet function with the argument "John". def factorial(n): if n == 0: return 1; else: return n * factorial(n-1) - Defines a recursive function to calculate the factorial of a number.
Modules and Packages
import math; print(math.pi) - Imports the math module and prints the value of pi. import datetime; print(datetime.date.today()) - Imports the datetime module and prints today's date. from random import randint; print(randint(0, 100)) - Imports a specific function from the random module and prints a random integer.
Error Handling
try: open("file.txt", "r").read(); except Exception as e: print("An error occurred:", e) - Attempts to read contents of a file; if an error occurs, it catches and prints the exception message. try: int(input()); except ValueError: print("Invalid input!") - Attempts to convert user input to an integer; if invalid input is provided, it catches and prints an error message.
Networking
import socket; s = socket.socket(socket.AF_INET, socket.SOCK_STREAM); s.connect(("www.example.com", 80)) - Creates a socket object and connects to a website. import http.client; c = http.client.HTTPConnection("www.example.com"); c.request("GET", "/") - Makes an HTTP request to a website.
System and Process Management
os.system("ls -l") - Runs the ls command using the os module. import subprocess; subprocess.run(["echo", "Hello, World!"], shell=True) - Runs a command that prints a greeting message.
This list is by no means exhaustive, but it covers many fundamental concepts and operations in Python shell scripting.
How do I run a Python script like a shell script?
Running a Python script as if it were a shell script! That's a great question.
First, let's understand why you'd want to do this. Shell scripts are often used for automating tasks that involve system administration, file manipulation, and process control. Python is an excellent choice when you need more flexibility and power in your scripting. By "running a Python script like a shell script," I'll show you how to make your Python code behave similarly to a shell script.
To get started, let's talk about the key differences between shell scripts and Python scripts:
#!/bin/bash. In contrast, Python scripts usually start with a hash symbol (#) for comments or use the Python-specific # -*- coding: utf-8 -*- declaration. Scripting syntax: Shell scripts use shell-specific commands and syntax (e.g., cd, mkdir, cp, etc.). Python scripts, on the other hand, rely on the Python language's syntax (e.g., functions, classes, conditionals, loops, etc.). Environment variables: Shell scripts have access to environment variables like $PATH and $HOME. In Python, you can access these variables using os.environ.
Now that we've established the differences, let's get started with making your Python script behave like a shell script!
Here are some strategies to help you achieve this:
1. Use sys.argv: Just like shell scripts receive command-line arguments through $@, Python scripts can use sys.argv to access the command-line arguments passed to them.
Example:
import sys
print("Received arguments:", ' '.join(sys.argv[1:]))
Call this script with python your_script.py arg1 arg2 and it'll print out ["arg1", "arg2"].
2. Utilize the subprocess module: When you need to execute external commands or shell scripts within a Python script, consider using subprocess. This module allows you to run processes in a more controlled environment.
Example:
import subprocess
Run a command using subprocess
result = subprocess.run(["echo", "Hello from Python!"], stdout=subprocess.PIPE)
print(result.stdout.decode("utf-8").strip())
3. Leverage os and pathlib modules: For file manipulation, use the os or pathlib modules to interact with your system's files.
Example:
import os
Create a directory using os.makedirs()
os.makedirs("new_dir", exist_ok=True)
Check if a file exists using path.exists()
if not pathlib.Path("example.txt").exists():
print("File does not exist!")
else:
print("File exists!")
4. Define your own shell-like syntax: If you want to create a more shell-like experience for users of your Python script, define your own commands or shortcuts using functions and conditionals.
Example:
def cd(directory):
os.chdir(directory)
print(f"Changed directory to {os.getcwd()}")
def rm(filename):
if os.path.exists(filename):
os.remove(filename)
print(f"{filename} removed!")
else:
print(f"{filename} does not exist!")
Example usage:
cd("/path/to/newdir")
rm("example.txt")
In conclusion, while Python scripts and shell scripts serve different purposes, you can still make your Python code behave like a shell script by leveraging the sys, subprocess, os, and pathlib modules. By defining your own commands or shortcuts, you can create a more shell-like experience for users of your Python script.
Remember, the key to success is understanding the differences between these two scripting paradigms and using their unique strengths to achieve your goals!
