4.3. Unknown Local Offset Convention
If the time in UTC is known, but the offset to local time is unknown,
this can be represented with an offset of "-00:00". This differs
semantically from an offset of "Z" or "+00:00", which imply that UTC
is the preferred reference point for the specified time.
That's not what we intend to convey in this case, is it?
I realize that the we're not trying to output RFC3339, but I think it could lead to confusion.
Jon
When the time zone has UT offset 0 and the time zone abbreviation
begins with "-", the %z spec now expands to -0000 instead of to
+0000. This conveys more-useful info, and is what the next
version of GNU 'date' is intended to do.
* NEWS, newstrftime.3: Document change.
* date.1: Document %z.
* strftime.c (_fmt): Implement change.
---
NEWS | 4 ++++
date.1 | 1 +
newstrftime.3 | 12 ++++++++++++
strftime.c | 13 ++++++++++++-
4 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/NEWS b/NEWS
index 8276cc7..3975295 100644
--- a/NEWS
+++ b/NEWS
@@ -74,6 +74,10 @@ Unreleased, experimental changes
when TZ is set to a POSIX-style string that specifies DST.
(Problem reported by Kees Dekker.)
+ date and strftime now cause %z to generate "-0000" instead of
+ "+0000" when the UT offset is zero and the time zone abbreviation
+ begins with "-".
+
Changes to documentation and commentary
tz-link.htm now covers leap smearing, which is popular in clouds.
diff --git a/date.1 b/date.1
index 7fd4848..579ab92 100644
--- a/date.1
+++ b/date.1
@@ -90,6 +90,7 @@ to be output in a particular way
%X 14:54:40 Time*
%y 89 Last two digits of year
%Y 1989 Year in full
+%z -0500 Numeric time zone
%Z EST Time zone abbreviation
%+ Wed Mar 8 14:54:40 EST 1989 Default output format*
.if t .in -.5i
diff --git a/newstrftime.3 b/newstrftime.3
index 9a60ee3..8f1be34 100644
--- a/newstrftime.3
+++ b/newstrftime.3
@@ -50,6 +50,13 @@ strftime \- format date and time
.SH DESCRIPTION
.ie '\(en'' .ds en \-
.el .ds en \(en
+.ie '\(lq'' .ds lq \&"\"
+.el .ds lq \(lq\"
+.ie '\(rq'' .ds rq \&"\"
+.el .ds rq \(rq\"
+.de q
+\\$3\*(lq\\$1\*(rq\\$2
+..
The
.I strftime
function formats the information from
@@ -211,6 +218,11 @@ is replaced by the offset from the Prime Meridian
in the format +HHMM or \*-HHMM as appropriate,
with positive values representing locations east of Greenwich,
or by the empty string if this is not determinable.
+The numeric time zone \*-0000 is used when the time is Universal Time
+but local time is indeterminate; by convention this is used for
+locations while uninhabited, and corresponds to a zero offset when the
+time zone abbreviation begins with
+.q "\*-" .
.TP
%%
is replaced by a single %.
diff --git a/strftime.c b/strftime.c
index 984ead5..2bfb6c1 100644
--- a/strftime.c
+++ b/strftime.c
@@ -500,6 +500,7 @@ label:
{
long diff;
char const * sign;
+ bool negative;
# ifdef TM_GMTOFF
diff = t->TM_GMTOFF;
@@ -538,7 +539,17 @@ label:
continue;
# endif
# endif
- if (diff < 0) {
+ negative = diff < 0;
+ if (diff == 0) {
+#ifdef TM_ZONE
+ negative = t->TM_ZONE[0] == '-';
+#else
+ negative
+ = (t->tm_isdst < 0
+ || tzname[t->tm_isdst != 0][0] == '-');
+#endif
+ }
+ if (negative) {
sign = "-";
diff = -diff;
} else sign = "+";
--
2.7.4