minix/lib/libc/time/offtime.3
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

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.\" $NetBSD: offtime.3,v 1.2 2010/12/16 18:38:07 christos Exp $
.\" Written by Klaus Klein, May 10, 2004.
.\" Public domain.
.Dd December 14, 2010
.Dt OFFTIME 3
.Os
.Sh NAME
.Nm offtime ,
.Nm timeoff ,
.Nm timegm ,
.Nm timelocal
.Nd convert date and time
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In time.h
.Ft struct tm *
.Fn offtime "const time_t * clock" "long int offset"
.Ft struct tm *
.Fn offtime_r "const time_t * clock" "long int offset" "struct tm *ret"
.Ft time_t
.Fn timeoff "struct tm * tm" "long int offset"
.Ft time_t
.Fn timegm "struct tm * tm"
.Ft time_t
.Fn timelocal "struct tm * tm"
.Sh DESCRIPTION
These functions are inspired by C standard interfaces named similarly.
.Pp
.Fn offtime
converts the calendar time
.Fa clock ,
offset by
.Fa offset
seconds,
into broken-down time, expressed as Coordinated Universal Time (UTC).
.Pp
.Fn offtime_r
is similar to
.Fn offtime
but it places the returned
.Ft "struct tm *"
in the user supplied
.Fa ret
argument.
.Pp
.Fn timeoff
converts the broken-down time
.Fa tm ,
expressed as UTC,
offset by
.Fa offset
seconds,
into a calendar time value.
.Pp
.Fn timegm
converts the broken-down time
.Fa tm
into a calendar time value, effectively being the inverse of
.Xr gmtime 3 .
It is equivalent to the C standard function
.Xr mktime 3
operating in UTC.
.Pp
.Fn timelocal
converts the broken down time
.Fa tm ,
expressed as local time, into a calendar time value.
It is equivalent to the C standard function
.Xr mktime 3 ,
and is provided for symmetry only.
.Sh SEE ALSO
.Xr ctime 3 ,
.Xr tzset 3