Score:-1

Ubuntu

Why is `man 3 printf` almost one year behind `glibc ver 2.35`?

Seamus

12/19/23, 11:48 PM

glibc ver 2.35 was released 0n Feb 3, 2022, and added the %b and %B binary conversion specifiers. This is a long wished-for feature to display values as a string of "ones and zeros". I'd like to use it.

I am running Ubuntu 22.04. My glibc version:

$ ldd --version
ldd (Ubuntu GLIBC 2.35-0ubuntu3.1) 2.35

I checked the Linux Programmer's Manual for printf:

man 3 printf

Unfortunately, there's not a word about these new binary format specifiers. They are not even listed. They are in printf; I can use them, but get unexpected results.

I was under the mistaken impression that apt updated manuals to be consistent with applications & libraries. Is this not how it works in Ubuntu? What must be done to get the current version of Programmer's Manual for printf that includes the new binary conversion specifiers %b & %B ?

1 + 12

documentation

manpage

glibc

ubfan1

12/20/23, 12:44 AM

Submit a documentation bug at https://bugs.launchpad.net/ubuntu

muru

12/20/23, 4:14 AM

Those manpages aren't maintained by glibc, but by the folks at https://www.kernel.org/doc/man-pages/contributing.html. To see the documentation provided by glibc developers, run `info printf`

Seamus

12/20/23, 4:41 AM

@muru: `info printf` doesn't even describe `%b` the same way it's described in the [announcement](https://web.archive.org/web/20221016003354/https://sourceware.org/pipermail/libc-alpha/2022-February/136040.html).

muru

12/20/23, 6:21 AM

@Seamus is the difference material? If so, I'd consider the `info` page authoritative since there's a good chance it was witten concurrent with the development of the feature.

Seamus

12/20/23, 7:32 AM

@muru: I'd say it's very material... it's as if they're talking about two completely different functions. Have you looked at the announcement I linked in my cmt above & `info printf`?

muru

12/20/23, 8:59 AM

Yes. Here's what it says for me in the info page: "'%b', '%B' Print an integer as an unsigned binary number. '%b' uses lower-case 'b' with the '#' flag and '%B' uses upper-case. '%b' is an ISO C2X feature; '%B' is an extension recommende\d by ISO C2X." And in the announcement: "printf-family functions now support the %b format for output of integers in binary, as specified in draft ISO C2X, and the %B variant of that format recommended by draft ISO C2X." I fail to see how the announcement disagrees in any meaningful way with the info page.

steeldriver

12/20/23, 3:02 PM

@Seamus I suspect you are looking at the `coreutils` info node, which describes the implementation of the printf command-line utility (equivalent to the `man 1 printf` page) rather than the printf system call. Try `info libc 'output conversions'` (you may need to install the `glibc-doc-reference` package).

Seamus

12/21/23, 2:00 AM

@steeldriver: Thanks for the clarification; installing the `glibc-doc-reference` package got the `info libc`document, but I still don't see any details wrt using `%b` or `%B` in a program.

steeldriver

12/21/23, 2:09 AM

@Seamus strange... did you navigate to the node I mentioned (more precisely, `12.12.3 Table of Output Conversions`)

Seamus

12/21/23, 2:16 AM

@muru: Then I guess you're looking at a different document than I am. According to another comment, you may have given me the wrong document with `info printf`?? But that raises the question, what document are you actually quoting in your last coment? ... it isn't `info printf`.

Seamus

12/21/23, 2:26 AM

@steeldriver: Yes, I did see that, but I was expecting more detail - it doesn't seem to agree with the output I got when I tried it. Quoting my code is probably getting a bit deep for these comments, and it seems the answer to the question I posted here is simply, "`It hasn't been released yet, try 'info libc output conversions'`" - which I'll gladly accept as the correct answer if you want to post it. Wrt usage of `%b`, perhaps I should ask another question, but that may be more appropriate for S.O... whaddya' think?

muru

12/21/23, 2:56 AM

@Seamus *I* didn't give you the wrong document, your system did. If I did `man printf` without specifying a section, the particular manpage I get depends on the manpages present in the system. The same is true for `info`. I had glibc docs installed but not coreutils, so for me, `info printf` shows the glibc one without having to qualify it. From there, I just searched instead of wading through multiple paragraphs looking for this. So, yes, I most definitely was quoting `info printf`. Maybe look at the first and last lines of your `info` output to identify what document and section.

Score:0

Ubuntu

Seamus

1/22/24, 11:11 PM

Apparently the glibc manpage(s) are not maintained by the same team that maintains glibc itself - as explained here. As noted in the comments, a facsimile of man 3 printf is available as info printf, but (at least IMHO) it's not quite as well organized or informative as a developer's manual.

Nevertheless, the glibc website has a Documentation tab, which in turn has a link to the complete glibc manual which is the canonical source for API descriptions, and available in several formats. This isn't quite as convenient as man 3 printf, but perhaps we won't have to wait much longer for the new binary format specifiers (%b and %B) to reach the man page.

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