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0 pointsswozey2y ago0 comments

I've never even thought about this. I think this is kind of strange

> An option and its argument may or may not appear as separate tokens. (In other words, the whitespace separating them is optional.) Thus, -o foo and -ofoo are equivalent.

Thanks this is super helpful I never knew this was a GNU thing.

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2 comments · 1 top-level

yjftsjthsd-h2y ago· 1 in thread

Note that there's an opposite convention that I think originated with the BSDs, where -ofoo is equivalent to -o -f -o -o

cb3212y ago

That only holds when 'o' and 'f' are both boolean "flags" taking no arguments. If 'f' is more like --file=x then it takes an argument.

More specifically, getopt(3) in POSIX lets programmers very this by giving a format string. "o:f" would make your example parse as "-o" "foo" while "of:" would make it parse as "-o" "-f" "oo" and an "of" format would make it parse as you describe, "-o" "-f" "-o" "-o".

( darnir mentioned parts of this above: https://news.ycombinator.com/item?id=38968612 using the term "single character flags" to indicate no argument. )

Also, while --long-option is GNU, gcc which is perhaps the aboriginal GNU command-line utility uses single dash as in, e.g. `gcc -pipe`, though it also accepts `gcc --help`. CL syntax remains quite varied in the wild.

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