Python命令行参数语法中[]、{}、-、--符号含义解析

Hey there! Let’s break down each symbol from your example prompt Usage : example.py [-h] example --example {example}—these are standard conventions for command-line tool documentation, so once you get the hang of them, you’ll parse these prompts effortlessly:

• Square brackets []: These mark optional arguments. In your example, [-h] means you can choose to include -h (the help flag) when running the program, or skip it entirely. If you include it, the program will typically display its help documentation and exit.

• Curly braces {}: These denote a required set of predefined choices—you must pick exactly one value from the options inside the braces. Your example uses {example} as a placeholder, which would normally be replaced with something like {foo,bar,baz} to show valid options for the --example flag.

• Single dash -: This is for short command-line options, usually single letters. They’re concise alternatives to longer flags. For example, -h is the common short version of --help across most CLI tools. You can often combine multiple short options into one (like -hv to enable help + verbose mode).

• Double dash --: This signals a long command-line option, typically a full word or phrase. Long options are more readable than short ones, making them great for clarity when you want to avoid ambiguity. In your example, --example is a long flag that requires a corresponding value from the {example} set of choices.

To make this tangible, here are valid commands using your prompt structure:

• Run the program without the optional help flag: example.py my_input --example valid_option (where valid_option is a choice from the {example} set)
• Run with the help flag to get more details: example.py -h (note: most tools accept -h on its own, but prompt structures can vary slightly by program)

内容的提问来源于stack exchange，提问作者OhMyGirl555