I'm writing a specification for a tool that needs a -f / --foo option with a mandatory argument BAR, so for example these are valid calls:tool -f BARtool --foo BARHow do I specify this syntax in the invocation section of a manpage or another formal definition?This would mean the options are not required, which is not what I intend:tool [-f BAR | --foo BAR]But simply omitting the brackets would not make sense either, since the pipe could be mistaken for an actual shell pipe.POSIX does not have long options, and I cannot find a GNU reference for that either.
How do I specify command invocation for a mandatory short or long option?
command line;man;options;documentation