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Comment by Spivak | Hacker News Reader

Counterexamples where this is good for legibility.

    tar -xf archive.tar.gz

    tar -czf archive.tar.gz dir/

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I'm guessing the comment was talking about examples like this:

    program -abcdefg.txt

Just from reading this, you can't tell where the flags end and the filename begins unless you have all the flags and their arities memorized.

Worse than that, it adds an unstable convention to an otherwise stable interface. What if there used to be a, b flags and then they add a c flag? Who knows what your command does now. It's just bad all around.

It’s not unstable or ambiguous at all.

    -abcdefg.txt

In your hypothetical -b takes an argument which means it consumes all the characters following it. Anything following b is never interpreted as a flag. There is no danger of -c changing the parsing. Even if b takes an optional argument it still consumes all characters following it.

Ah, you are right.

That’s always true even before you talk about option combining.

    python scr.py -a -v

Interpreting this command correctly requires you to know that python passes everything after the first positional argument to the script.

    ansible play.yml -v

Where ansible itself consumes the -v argument.

It gets even worse with subcommands.

    sudo -k command -a subcommand -v

Options parsing is nice because the arity of options is always 0 or 1.

> tar -czf dir/

You forgot the output filename.

The thing I like about tar is that you only need to learn two options: 'c' and 'x':

    tar c somedir | gzip > somedir.tar.gz
    cat somedir.tar.gz | gunzip | tar x

Thank you! Fixed!

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