The BUGS section already explains why you need to be cautious
about using mallinfo, but given the number of bug reports we see
on Android, it seems not many people are reading that far. Call it
out up front.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk [Sun, 14 Apr 2019 17:34:35 +0000 (19:34 +0200)]
clone.2: CLONE_CHILD_SETTID has effect before clone() returns *in the child*
CLONE_CHILD_SETTID may not have had effect by the time clone()
returns in the parent, which could bre relevant if the
CLONE_VM flag is employed. The relevant kernel code is in
schedule_tail(), which is called in ret_from_fork()
in the child.
See https://bugzilla.kernel.org/show_bug.cgi?id=203105
Demonstration using the program shown below (inspired by a simpler
example from Jakub):
Carlos O'Donell [Thu, 28 Mar 2019 18:01:28 +0000 (14:01 -0400)]
malloc_trim.3: Update trimming information
Since glibc 2.8, commit 68631c8eb92, the malloc_trim function has
iterated over all arenas and free'd back to the OS all page runs
that were free. This allows an application to call malloc_trim to
consolidate fragmented chunks and free back any pages it can to
potentially reduce RSS usage.
This correctness of the man page was recently brought to light by
an article [1] where Ruby developers discovered that malloc_trim
did not behave as the man page indicated.
This change makes it clear that the intent of malloc_trim is to
trim all space that is no longer needed, and any restrictions are
implementation details. In the notes we highlight the change in
behaviour for post glibc 2.8 and pre glibc 2.8.
Where is the initial read position for an "a+" stream?
POSIX leaves this unspecified. Most BSD man pages are silent, and MacOS
has the ambiguous "The stream is positioned at the end of the file", not
differentiating between reads and writes other than to say that fseek(3)
does not affect writes. glibc's documentation explicitly specifies that
the initial read position is the beginning of the file.
My new wording is based on the BSD implementations, so you may prefer
to replace the non-glibc section with "unspecified", or indeed remove
all claims about the initial read position.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk [Fri, 12 Apr 2019 09:11:03 +0000 (11:11 +0200)]
stdarg.3: Add a note that ... in function signature means a variadic function
Egmont suggested adding this, because the string "..." appears
at several other points in the page, but just to indicate that
some text is omitted from example code.
Reported-by: Egmont Koblinger <egmont@gmail.com> Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk [Fri, 12 Apr 2019 08:56:59 +0000 (10:56 +0200)]
syscalls.2: Remove crufty text about i386 syscall dispatch table
The removed text long ago ceased to be accurate. Nowadays, the
dispatch table is autogenerated when building the kernel (via
the kernel makefile, arch/x86/entry/syscalls/Makefile).
Reported-by: Andreas Korb <andreas.d.korb@gmail.com> Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk [Tue, 26 Mar 2019 04:58:54 +0000 (05:58 +0100)]
setfsuid.2: Rewrite for improved clarity and to hint history more explicitly
The current text reads somewhat clumsily. Rewrite it to introduce
the eUID and fsUID in parallel, and more clearly hint at the the
historical rationale for the fsUID, which is detailed lower in
the page.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk [Tue, 4 Dec 2018 08:35:39 +0000 (09:35 +0100)]
dlsym.3: Describe a case where a symbol value may be NULL
Remove a longstanding mystery in the text of the page, by
explaining a case where the value returned for a symbol may be
NULL. (However, there are presumably other cases, since the text
in the dlsym(3) manual page pre-dates the invention of IFUNCs.)
See also
https://stackoverflow.com/questions/13941944/why-can-the-value-of-the-symbol-returned-by-dlsym-be-null
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk [Wed, 27 Feb 2019 14:19:05 +0000 (15:19 +0100)]
mdoc.7, mdoc.samples.7: Remove these pages
groff_mdoc(7) from the groff project provides a better
equivalent of mdoc.samples(7) and the 'mandoc' project
provides a better mdoc(7). And nowadays, there are virtually
no pages in "man-pages" that use mdoc markup.
So, drop these pages.
From a conversation on linux-man with Ingo Schwarz:
[[
Subject: Re: [groff] [PATCH] man7/mdoc_samples.7: srcfix: Avoid a warning about a wrong section
Date: Wed, 27 Feb 2019 15:28:19 +0100
> The two actual problems are both within the Linux man-pages project,
> not within groff:
>
> 1. While back in the early 1990ies, Cynthia Livingston's
> mdoc.samples(7) manual page was an important document and the
> de-facto language definition of the mdoc(7) language, it has
> been outdated for a long time now. The current groff_mdoc(7)
> manual page is based on it but contains large numbers of important
> improvements by Werner Lemberg and others. As an alternative
> language definition that is slightly more concise without being
> less precise and complete, the mdoc(7) manual page is available
> from the mandoc(1) distribution (mandoc.bsd.lv). If there are
> any contradictions between groff_mdoc(7) and mdoc(7), those are
> unintended and i ought to fix them.
>
> So i really believe that the Linux man-pages project ought to
> stop distributing the woefully outdated mdoc.samples(7) manual
> page. If you want to include documentation for the mdoc language,
> i suggest that you either include a copy of the current version
> of the groff_mdoc(7) manual from the groff(1) distribution or
> of the mdoc(7) manual from the mandoc(1) distribution, whichever
> you think harmonizes better with the Linux man-pages project.
> Both are BSD-style licensed, so there should be no licensing
> issues.
>
> I'm not sure whether it is better for you to include or not
> include it. There is probably value in having mdoc(7) documentation
> out of the box with the Linux man-pages project. Then again,
> having groff_mdoc(7) in both the Linux man-pages package and
> in the groff package - or having mdoc(7) in both the Linux
> man-pages project and the mandoc(1) package - might cause
> packaging conflicts for some distributions. I don't rightly
> know how such conflicts are typically handled by Linux
> distributions. Not being able to install the Linux man-pages
> pages project, groff(1) and mandoc(1) all together on the same
> Linux machine would certainly be a bad situation...
>
> By the way, the mdoc(7) manual page distributed by the Linux
> man-pages project also makes very little sense. It is a partial
> repetition of information from groff_mdoc(7)/[mandoc-]mdoc(7),
> but so compressed that it is mostly unintelligible. Besides,
> it is incomplete: e.g. .Lk, .Mt, .Dx, .Ox, .Nx, .Ta, .%U, .Bk,
> .Ek, .Lb, .In, .Ft, .Ms, .Brq, .Bro, .Brc, .Ex are missing -
> it seems outdated by at lest 25 years. Also, some claims are
> outright wrong - for example, you *cannot* use .UR/.UE in an
> mdoc(7) document, and i cannot remember ever having seen an
> implementation of a .UN macro anywhere. Some macros descriptions
> are also wrong, e.g. .Fd is *not* intended for "function
> declarations", and .Vt is *not* "Fortran only". And so on.
>
> 2. I don't recommend keeping the old mdoc.samples(7) and mdoc(7)
> manual pages, but if you think you must do that for some reason,
> then you must at least revert this bogus commit:
I am *not at all* attached to keeping to these pages. Their
presence in the project has always felt a bit anomalous to me.
Back when I took over maintainership in 2004, there were a small
number of pages that used mdoc markup, and so it seemed wise
to keep these pages. Over time, most of those few pages were
converted to 'man' markup, and today the only other page in the
project that still uses mdoc markup is in queue(3). So, there is
just about zero value in having 'mdoc' documentation come with
the "Linux man-pages" box.
Since I seldom use mdoc markup myself, I've had no reason to
monitor pages such as groff_mdoc(7) or the mdoc(7) page
provided my ther 'mandoc' project and compare them with
the pages provided by "Linux man-pages". Now I've had a
closer look. It's sad.
I've removed mdoc(7) and mdoc.samples(7) from "Linux -man-pages".
]]
*roff escape sequences may sometimes look like C escapes, but that
is misleading. *roff is in part a macro language and that means
recursive expansion to arbitrary depths.
You can get away with "\\" in a context where no macro expansion
is taking place, but try to spell a literal backslash this way in
the argument to a macro and you will likely be unhappy with
results.
Try viewing the attached file with "man -l".
"\e" is the preferred and portable way to get a portable "escape
literal" going back to CSTR #54, the original Bell Labs troff
paper.
groff(7) discusses the issue:
\\ reduces to a single backslash; useful to delay its
interpretation as escape character in copy mode. For a
printable backslash, use \e, or even better \[rs], to be
independent from the current escape character.
As of groff 1.22.4, groff_man(7) does as well:
\e Widely used in man pages to represent a backslash output
glyph. It works reliably as long as the .ec request is
not used, which should never happen in man pages, and it
is slightly more portable than the more exact ‘\(rs’
(“reverse solidus”) escape sequence.
People not concerned with portability to extremely old troffs should
probably just use \(rs (or \[rs]), as it means "the backslash
glyph", not "the glyph corresponding to whatever the current escape
character is".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk [Wed, 27 Feb 2019 11:23:42 +0000 (12:23 +0100)]
adjtimex.2, futex.2, mremap.2, seccomp.2, getnameinfo.3, random.3, console_codes.4, sysfs.5, sched.7, unicode.7: Use zero‐width space in appropriate locations
Quoting Branden:
*roff systems will interpret the period in the unpatched
page as sentence-ending punctuation and put inter-sentence
spacing after it. (This might not be visible on
nroff/terminal devices, but it is more likely to be on
typesetter/PostScript/PDF output).
groff_man(7) in groff 1.22.4 attempts to throw man page
writers a bone here:
\& Zero‐width space. Append to an input line to prevent
an end‐of‐ sentence punctuation sequence from being
recognized as such, or insert at the beginning of an
input line to prevent a dot or apostrophe from being
interpreted as the beginning of a roff request.
Reported-by: Bjarni Ingi Gislason <bjarniig@rhi.hi.is> Reported-by: G. Branden Robinson <g.branden.robinson@gmail.com> Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
projects / thirdparty / man-pages.git / log
