21 Sep
2023
21 Sep
'23
3:37 p.m.
On Wed, Sep 20, 2023 at 12:56:35PM -0700, Larry McVoy wrote:
On Tue, Sep 19, 2023 at 07:25:13PM -0700, Adam
Thornton wrote:
These days, I find the much more useful sections are VERSIONS and
STANDARDS, e.g.:
VERSIONS
openat() was added in Linux 2.6.16; library support was added
in glibc 2.4.
STANDARDS
open(), creat() SVr4, 4.3BSD, POSIX.1‐2001, POSIX.1‐2008.
openat(): POSIX.1‐2008.
openat2(2) is Linux‐specific.
The O_DIRECT, O_NOATIME, O_PATH, and O_TMPFILE flags are
Linux‐specific. One must define _GNU_SOURCE to obtain their
definitions.
The O_CLOEXEC, O_DIRECTORY, and O_NOFOLLOW flags are not
specified in POSIX.1‐2001, but are specified in POSIX.1‐2008.
Since glibc 2.12, one can obtain their definitions by defining
either _POSIX_C_SOURCE with a value greater than or equal to
200809L or _XOPEN_SOURCE with a value greater than or equal to
700. In glibc 2.11 and earlier, one obtains the definitions by
defining _GNU_SOURCE.
As noted in feature_test_macros(7), feature test macros such as
_POSIX_C_SOURCE, _XOPEN_SOURCE, and _GNU_SOURCE must be defined
before including any header files.
- Ted
Yeah, I'm less angry at GNU now--I
didn't search as hard, but when I found
out 4.3BSD didn't have HISTORY (and neither does 2.11BSD, which is still
actively-ish maintained) then I figured it wasn't something classical that
GNU dropped, just never imported. I feel like it existed on SunOS and
Solaris but I might be wrong about that? Was it really FreeBSD that
introduced it?
I don't think SunOS had it. The SunOS man pages were pretty terse, the
powers that be wanted just the facts. I remember get beat up for putting
examples in some of the man pages I wrote, they got taken out "because
examples are for user guides, man pages are not user guides, they are a
reference guide" or something like that.