Gfrktyl

For instance, taking a look at

man stat

in the description, there's several options like:

-L, --dereference

and

-c --format=FORMAT

what is the difference with or without a comma? And how do I learn this kind of stuff. I'm afraid I might be missing some simple detail.

I'm currently reading: http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html

But it doesn't seem to say a lot. How/where do you consult information about Linux?

In stat specifically, this looks like a typo. The -c and --format options are interchangable and so the comma should be there for style consistency with the other options.

The way it reads is that you need -c then --format which is not the case.

what is the difference with or without a comma?

None. Use either short or long option, the comma doesn't matter.

In my Kubuntu I copied files from /usr/share/man/man1 and /usr/share/man/man8, decompressed, sanitized (removed fluff) and searched with regex for options without the comma. I browsed the results, examined few "suspicious" files. My conclusions (heuristic, not strict):

• Relatively few manuals use the no-comma style.


• Those which do rarely mix it with the with-comma style.


• 
  man stat uses no-comma for -c --format only, it's probably just a typo.

how do I learn this kind of stuff?

My way: by getting familiar with. Man pages are for people; most people (even nerds) are able to deal with fuzzy patterns, typos, little inconsistencies or exceptions. Some manuals are so huge (man 1 bash) or need to deal with abstract concepts (man 5 sudoers), so they are more formal; but when you need to solve a specific problem you rarely study the whole manual, you seek examples. So you experiment, adapt available examples, write commands that don't work, write commands that do work, compare whatever works against the documentation.

And then you start to know these somewhat fuzzy conventions. You rely on the Rule of Least Surprise, you expect to see some short options equivalent to some long options. You don't even notice some manuals omit commas. You see man stat is inconsistent only because the lacking comma stands out visually; you shrug and carry on…

… because you're familiar with some other manuals that explicitly warn you about surprising syntax, if any; and you think it's great their authors did such a good thing.

But even if there was a difference with or without a comma, how much can it matter? since

• you run stat -c '%n' / and get / which is expected;


• you run stat --format='%n' / and get the same result;

but

• you run stat -c --format='%n' / and get --format=/.

I'm afraid I might be missing some simple detail.

Compare this to the case of ellipsis in menus of GUI tools. Did you know many applications use ellipsis (…) to denote menu items that don't take immediate action? E.g. Print… spawns additional window where you can change something before you proceed with the actual printing, or you can cancel; in such application Print (without ellipsis) would print right away.

I had been using GUI tools efficiently for several years, before I learnt what ellipsis mean. It was by chance, I read some trivia and only then I noticed ellipsis are (and "always" were) there. Now I know any menu item with ellipsis is "safe", it should provide me a way to cancel.

My point is: such a detail may mean something, it may be quite useful (so you asked a reasonable question); but if you can make stat do what you want (and if I can use menus to get what I want) then missing the detail is not a big deal.