1.\" $NetBSD: offtime.3,v 1.4 2017/10/25 19:01:25 abhinav Exp $ 2.\" Written by Klaus Klein, May 10, 2004. 3.\" Public domain. 4.Dd May 4, 2019 5.Dt OFFTIME 3 6.Os 7.Sh NAME 8.Nm offtime , 9.Nm timeoff , 10.Nm timelocal 11.Nd convert date and time 12.Sh LIBRARY 13.Lb libc 14.Sh SYNOPSIS 15.In time.h 16.Ft struct tm * 17.Fn offtime "const time_t * clock" "long int offset" 18.Ft time_t 19.Fn timeoff "struct tm * tm" "long int offset" 20.Ft time_t 21.Fn timelocal "struct tm * tm" 22.Sh DESCRIPTION 23These functions are inspired by C standard interfaces named similarly. 24.Pp 25.Fn offtime 26converts the calendar time 27.Fa clock , 28offset by 29.Fa offset 30seconds, 31into broken-down time, expressed as Coordinated Universal Time (UTC). 32.Pp 33.Fn timeoff 34converts the broken-down time 35.Fa tm , 36expressed as UTC, 37offset by 38.Fa offset 39seconds, 40into a calendar time value. 41.Pp 42.Fn timelocal 43converts the broken down time 44.Fa tm , 45expressed as local time, into a calendar time value. 46It is equivalent to the C standard function 47.Xr mktime 3 , 48and is provided for symmetry only. 49.Sh SEE ALSO 50.Xr ctime 3 , 51.\".Xr tm 3 , 52.Xr tzset 3 53