How to use command-line arguments?

Using command-line arguments allows you to pass information to scripts or programs when you run them from the command line. Here’s how to use command-line arguments in both Bash scripts and Python programs:

In Bash Scripts

1. Accessing Arguments: You can access command-line arguments using special variables:

   • $1, $2, $3, etc. for the first, second, third arguments, and so on.
   • $@ for all arguments.
   • $# for the number of arguments.

2. Example Script:

   #!/bin/bash
   echo "First argument: $1"
   echo "Second argument: $2"
   echo "Total number of arguments: $#"

3. Running the Script:

   ./script.sh arg1 arg2

In Python Programs

1. Using sys.argv: You can access command-line arguments using the sys module.

   • sys.argv is a list where the first element is the script name and subsequent elements are the arguments.

2. Example Script:

   import sys
   
   if len(sys.argv) > 1:
       print("First argument:", sys.argv[1])
       print("Second argument:", sys.argv[2])
       print("Total number of arguments:", len(sys.argv) - 1)
   else:
       print("No arguments provided.")

3. Running the Script:

   python script.py arg1 arg2

Summary

• In Bash, use $1, $2, etc., to access arguments.
• In Python, use sys.argv to access command-line arguments.
• Always check the number of arguments to avoid index errors.

If you have any specific use cases or need further examples, feel free to ask!