Hi, In "Conventions for Command Line Options", you describe "optional option arguments". Can you give an example of a tool that supports such an option? I'm struggling to see the use-case, and can't recall ever having seen this in the wild. Thanks, Ulysse
Half the various GNU utilities have at least one. Any that produce color output (ls, grep, etc.) have a --color option with an optional "WHEN" argument. ln, install, and mv have a --backup with optional CONTROL argument. df --output has an optional FIELD_LIST argument. mkdir, install, mkfifo, and mknod have --context with an optional CTX argument. ls and vdir have --hyperlink with an optional WHEN argument. mkdir --tmpdir has an optional DIR argument. rm has --interactive with an optional WHEN argument and --preserve-root with an optional ALL argument. sched has --remove with an optional HOW. od has --width with an optional BYTES, and it also comes with a short option version -w also taking optional BYTES. pr also has a whole bunch like this. I could keep going since GNU has so many examples, but I'll stop here! Git has a ton of them, too. Its --exec-path option takes an optional path. The show command has --pretty, --notes, and --show-notes with optional arguments. The log command has --decorate, --branches, --tags, --remotes, --no-walk, --pretty, --notes, --show-notes, --show-linear-break, --stat, --dirstat, --submodule, --color, --color-moved, --word-diff, --color-words, --abbrev, --break-rewrites (and -B), --find-renames, --find-copies, --relative, and --ignore-submodules all taking optional arguments. Again, I could probably list a hundred more just by further exploring the man pages. My own passphrase2pgp has --protect (-e), --expires (-x), and --pinentry each with an optional argument. My Enchive tool has --derive (-d) with an optional iteration count, as well as --pinentry and --agent. https://github.com/skeeto/passphrase2pgp#usage https://nullprogram.com/enchive/ Basically you need only grep "[=" in man pages to find them.