diff options
Diffstat (limited to 'man-pages-posix-2017/man0p/time.h.0p')
| -rw-r--r-- | man-pages-posix-2017/man0p/time.h.0p | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/man-pages-posix-2017/man0p/time.h.0p b/man-pages-posix-2017/man0p/time.h.0p new file mode 100644 index 0000000..51e7497 --- /dev/null +++ b/man-pages-posix-2017/man0p/time.h.0p @@ -0,0 +1,333 @@ +'\" et +.TH time.h "0P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" +.SH PROLOG +This manual page is part of the POSIX Programmer's Manual. +The Linux implementation of this interface may differ (consult +the corresponding Linux manual page for details of Linux behavior), +or the interface may not be implemented on Linux. +.\" +.SH NAME +time.h +\(em time types +.SH SYNOPSIS +.LP +.nf +#include <time.h> +.fi +.SH DESCRIPTION +Some of the functionality described on this reference page extends the +ISO\ C standard. Applications shall define the appropriate feature test macro +(see the System Interfaces volume of POSIX.1\(hy2017, +.IR "Section 2.2" ", " "The Compilation Environment") +to enable the visibility of these symbols in this header. +.P +The +.IR <time.h> +header shall define the +.BR clock_t , +.BR size_t , +.BR time_t , +types as described in +.IR <sys/types.h> . +.P +The +.IR <time.h> +header shall define the +.BR clockid_t +and +.BR timer_t +types as described in +.IR <sys/types.h> . +.P +The +.IR <time.h> +header shall define the +.BR locale_t +type as described in +.IR <locale.h> . +.P +The +.IR <time.h> +header shall define the +.BR pid_t +type as described in +.IR <sys/types.h> . +.P +The tag +.BR sigevent +shall be declared as naming an incomplete structure type, the contents +of which are described in the +.IR <signal.h> +header. +.P +The +.IR <time.h> +header shall declare the +.BR tm +structure, which shall include at least the following members: +.sp +.RS 4 +.nf + +int tm_sec \fRSeconds [0,60].\fR +int tm_min \fRMinutes [0,59].\fR +int tm_hour \fRHour [0,23].\fR +int tm_mday \fRDay of month [1,31].\fR +int tm_mon \fRMonth of year [0,11].\fR +int tm_year \fRYears since 1900.\fR +int tm_wday \fRDay of week [0,6] (Sunday =0).\fR +int tm_yday \fRDay of year [0,365].\fR +int tm_isdst \fRDaylight Savings flag.\fR +.fi +.P +.RE +.P +The value of +.IR tm_isdst +shall be positive if Daylight Savings Time is in effect, 0 if Daylight +Savings Time is not in effect, and negative if the information is not +available. +.P +The +.IR <time.h> +header shall declare the +.BR timespec +structure, which shall include at least the following members: +.sp +.RS 4 +.nf + +time_t tv_sec \fRSeconds.\fR +long tv_nsec \fRNanoseconds.\fR +.fi +.P +.RE +.P +The +.IR <time.h> +header shall also declare the +.BR itimerspec +structure, which shall include at least the following members: +.sp +.RS 4 +.nf + +struct timespec it_interval \fRTimer period.\fR +struct timespec it_value \fRTimer expiration.\fR +.fi +.P +.RE +.P +The +.IR <time.h> +header shall define the following macros: +.IP NULL 14 +As described in +.IR <stddef.h> . +.IP CLOCKS_PER_SEC 14 +A number used to convert the value returned by the +\fIclock\fR() +function into seconds. The value shall be an expression with type +.BR clock_t . +The value of CLOCKS_PER_SEC shall be 1 million +on XSI-conformant systems. However, it may be variable on other systems, +and it should not be assumed that CLOCKS_PER_SEC is a compile-time +constant. +.P +The +.IR <time.h> +header shall define the following symbolic constants. The values shall +have a type that is assignment-compatible with +.BR clockid_t . +.IP CLOCK_MONOTONIC 14 +.br +The identifier for the system-wide monotonic clock, which is defined as +a clock measuring real time, whose value cannot be set via +\fIclock_settime\fR() +and which cannot have negative clock jumps. The maximum possible clock +jump shall be implementation-defined. +.IP CLOCK_PROCESS_CPUTIME_ID 14 +.br +The identifier of the CPU-time clock associated with the process +making a +\fIclock\fR() +or +.IR timer* (\|) +function call. +.IP CLOCK_REALTIME 14 +The identifier of the system-wide clock measuring real time. +.IP CLOCK_THREAD_CPUTIME_ID 14 +.br +The identifier of the CPU-time clock associated with the thread making a +\fIclock\fR() +or +.IR timer* (\|) +function call. +.P +The +.IR <time.h> +header shall define the following symbolic constant: +.IP TIMER_ABSTIME 14 +Flag indicating time is absolute. For functions taking timer objects, +this refers to the clock associated with the timer. +.P +The +.IR <time.h> +header shall provide a declaration or definition for +.IR getdate_err . +The +.IR getdate_err +symbol shall expand to an expression of type +.BR int . +It is unspecified whether +.IR getdate_err +is a macro or an identifier declared with external linkage, and whether or +not it is a modifiable lvalue. If a macro definition is suppressed in +order to access an actual object, or a program defines an identifier +with the name +.IR getdate_err , +the behavior is undefined. +.P +The following shall be declared as functions and may also be defined +as macros. Function prototypes shall be provided. +.sp +.RS 4 +.nf + +char *asctime(const struct tm *); +char *asctime_r(const struct tm *restrict, char *restrict); +clock_t clock(void); +int clock_getcpuclockid(pid_t, clockid_t *); +int clock_getres(clockid_t, struct timespec *); +int clock_gettime(clockid_t, struct timespec *); +int clock_nanosleep(clockid_t, int, const struct timespec *, + struct timespec *); +int clock_settime(clockid_t, const struct timespec *); +char *ctime(const time_t *); +char *ctime_r(const time_t *, char *); +double difftime(time_t, time_t); +struct tm *getdate(const char *); +struct tm *gmtime(const time_t *); +struct tm *gmtime_r(const time_t *restrict, struct tm *restrict); +struct tm *localtime(const time_t *); +struct tm *localtime_r(const time_t *restrict, struct tm *restrict); +time_t mktime(struct tm *); +int nanosleep(const struct timespec *, struct timespec *); +size_t strftime(char *restrict, size_t, const char *restrict, + const struct tm *restrict); +size_t strftime_l(char *restrict, size_t, const char *restrict, + const struct tm *restrict, locale_t); +char *strptime(const char *restrict, const char *restrict, + struct tm *restrict); +time_t time(time_t *); +int timer_create(clockid_t, struct sigevent *restrict, + timer_t *restrict); +int timer_delete(timer_t); +int timer_getoverrun(timer_t); +int timer_gettime(timer_t, struct itimerspec *); +int timer_settime(timer_t, int, const struct itimerspec *restrict, + struct itimerspec *restrict); +void tzset(void); +.fi +.P +.RE +.br +.P +The +.IR <time.h> +header shall declare the following as variables: +.sp +.RS 4 +.nf + +extern int daylight; +extern long timezone; +extern char *tzname[]; +.fi +.P +.RE +.P +Inclusion of the +.IR <time.h> +header may make visible all symbols from the +.IR <signal.h> +header. +.LP +.IR "The following sections are informative." +.SH "APPLICATION USAGE" +The range [0,60] for +.IR tm_sec +allows for the occasional leap second. +.P +.IR tm_year +is a signed value; therefore, years before 1900 may be represented. +.P +To obtain the number of clock ticks per second returned by the +\fItimes\fR() +function, applications should call +.IR sysconf (_SC_CLK_TCK). +.SH RATIONALE +The range [0,60] seconds allows for positive or negative leap seconds. +The formal definition of UTC does not permit double leap seconds, so +all mention of double leap seconds has been removed, and the range +shortened from the former [0,61] seconds seen in earlier versions of +this standard. +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "\fB<locale.h>\fP", +.IR "\fB<signal.h>\fP", +.IR "\fB<stddef.h>\fP", +.IR "\fB<sys_types.h>\fP" +.P +.ad l +The System Interfaces volume of POSIX.1\(hy2017, +.IR "Section 2.2" ", " "The Compilation Environment", +.IR "\fIasctime\fR\^(\|)", +.IR "\fIclock\fR\^(\|)", +.IR "\fIclock_getcpuclockid\fR\^(\|)", +.IR "\fIclock_getres\fR\^(\|)", +.IR "\fIclock_nanosleep\fR\^(\|)", +.IR "\fIctime\fR\^(\|)", +.IR "\fIdifftime\fR\^(\|)", +.IR "\fIgetdate\fR\^(\|)", +.IR "\fIgmtime\fR\^(\|)", +.IR "\fIlocaltime\fR\^(\|)", +.IR "\fImktime\fR\^(\|)", +.IR "\fImq_receive\fR\^(\|)", +.IR "\fImq_send\fR\^(\|)", +.IR "\fInanosleep\fR\^(\|)", +.IR "\fIpthread_getcpuclockid\fR\^(\|)", +.IR "\fIpthread_mutex_timedlock\fR\^(\|)", +.IR "\fIpthread_rwlock_timedrdlock\fR\^(\|)", +.IR "\fIpthread_rwlock_timedwrlock\fR\^(\|)", +.IR "\fIsem_timedwait\fR\^(\|)", +.IR "\fIstrftime\fR\^(\|)", +.IR "\fIstrptime\fR\^(\|)", +.IR "\fIsysconf\fR\^(\|)", +.IR "\fItime\fR\^(\|)", +.IR "\fItimer_create\fR\^(\|)", +.IR "\fItimer_delete\fR\^(\|)", +.IR "\fItimer_getoverrun\fR\^(\|)", +.IR "\fItzset\fR\^(\|)", +.IR "\fIutime\fR\^(\|)" +.ad b +.\" +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1-2017, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 7, 2018 Edition, +Copyright (C) 2018 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. +In the event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.opengroup.org/unix/online.html . +.PP +Any typographical or formatting errors that appear +in this page are most likely +to have been introduced during the conversion of the source files to +man page format. To report such errors, see +https://www.kernel.org/doc/man-pages/reporting_bugs.html . |