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authorKarel Zak2006-12-07 00:25:43 +0100
committerKarel Zak2006-12-07 00:25:43 +0100
commit22853e4a82c6ef7b336527529acb94b14a0b0fd8 (patch)
treeee28e4598c8c449d7e811711d8ce8eb17caecfb6 /clock/hwclock.8
parentImported from util-linux-2.10f tarball. (diff)
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Imported from util-linux-2.10m tarball.
Diffstat (limited to 'clock/hwclock.8')
-rw-r--r--clock/hwclock.860
1 files changed, 26 insertions, 34 deletions
diff --git a/clock/hwclock.8 b/clock/hwclock.8
index ddf0c7c3e..f34bfac00 100644
--- a/clock/hwclock.8
+++ b/clock/hwclock.8
@@ -1,30 +1,30 @@
-.TH CLOCK 8 "02 March 1998"
+.TH HWCLOCK 8 "02 March 1998"
.SH NAME
-clock \- query and set the hardware clock (RTC)
+hwclock \- query and set the hardware clock (RTC)
.SH SYNOPSIS
-.B "hwclock \-\-show"
+.BR "hwclock \-r" " or " "hwclock \-\-show"
.br
-.B "hwclock \-\-set \-\-date=newdate"
+.BR "hwclock \-w" " or " "hwclock \-\-systohc"
.br
-.B "hwclock \-\-systohc"
+.BR "hwclock \-s" " or " "hwclock \-\-hctosys"
.br
-.B "hwclock \-\-hctosys"
+.BR "hwclock \-a" " or " "hwclock \-\-adjust"
.br
-.B "hwclock \-\-getepoch"
+.BR "hwclock \-v" " or " "hwclock \-\-version"
.br
-.B "hwclock \-\-setepoch \-\-epoch=year"
+.B "hwclock \-\-set \-\-date=newdate"
.br
-.B "hwclock \-\-adjust"
+.B "hwclock \-\-getepoch"
.br
-.B "hwclock \-\-version"
+.B "hwclock \-\-setepoch \-\-epoch=year"
.PP
other options:
.PP
-.B "\-\-utc \-\-localtime \-\-directisa \-\-test \-\-debug"
+.B "[\-u|\-\-utc] \-\-localtime \-\-directisa \-\-test \-\-debug"
.PP
and arcane options for DEC Alpha:
.PP
-.B "\-\-arc \-\-jensen \-\-srm \-\-funky-toy"
+.B "[\-A|\-\-arc] [\-J|\-\-jensen] [\-S|\-\-srm] [\-F|\-\-funky-toy]"
.PP
Minimum unique abbreviations of all options are acceptable.
.PP
@@ -67,16 +67,15 @@ option.
.B \-\-hctosys
Set the System Time from the Hardware Clock.
-Also set the kernel's timezone value to the local timezone as indicated by
-the TZ environment variable and/or
+Also set the kernel's timezone value to the local timezone
+as indicated by the TZ environment variable and/or
.IR /usr/lib/zoneinfo ,
as
.BR tzset (3)
-would interpret them. EXCEPT: always set the Daylight Savings Time part of
-the kernel's timezone value to 0 ("not Daylight Savings Time"). If DST
-is indicated, just add an hour to the base part.
-
-See the discussion of timezones below.
+would interpret them.
+The obsolete tz_dsttime field of the kernel's timezone value is set
+to DST_NONE. (For details on what this field used to mean, see
+.BR settimeofday (2).)
This is a good option to use in one of the system startup scripts.
.TP
@@ -356,21 +355,14 @@ sets the kernel timezone to the value indicated by TZ and/or
.B \-\-hctosys
option.
.PP
-A complication is that the timezone value actually consists of two
-parts: 1) how far from the Standard Meridian the locality is
-geographically, and 2) whether or not a Daylight Savings Time (DST)
-convention is in effect in the locality at the present time. In
-practice, the DST part of the timezone value is almost never used, so
-if the geographical part were to be set to its correct value, the
-users of the timezone value would actually compute the wrong local
-time.
-.PP
-Therefore,
-.I hwclock
-violates the definition of the kernel's timezone value and always sets
-the DST part to zero. If DST is supposed to be in effect,
-.I hwclock
-simply adds an hour to the geographical part.
+The timezone value actually consists of two parts: 1) a field
+tz_minuteswest indicating how many minutes local time (not adjusted
+for DST) lags behind UTC, and 2) a field tz_dsttime indicating
+the type of Daylight Savings Time (DST) convention that is in effect
+in the locality at the present time.
+This second field is not used under Linux and is always zero.
+(See also
+.BR settimeofday (2).)
.SH How hwclock Accesses the Hardware Clock
.PP