'\" t
.\" SPDX-License-Identifier: 0BSD
.\"
.TH timespec_get 3 2026-02-11 "Linux man-pages 6.19"
.SH NAME
timespec_get,
timespec_getres
\-
ISO C interface to clock and time functions
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.B #include <time.h>
.P
.BI "int timespec_get(struct timespec *" res ", int " base );
.BI "int timespec_getres(struct timespec *" tp ", int " base );
.fi
.P
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.P
.BR timespec_get (),
.BR TIME_UTC :
.nf
    _ISOC11_SOURCE
.fi
.P
.BR timespec_getres (),
.BR TIME_MONOTONIC ,
.BR TIME_ACTIVE ,
.BR TIME_THREAD_ACTIVE :
.nf
    _ISOC23_SOURCE
.fi
.SH DESCRIPTION
The
.BR timespec_get ()
function stores the current time, based on the specified time base, in the
.BR timespec (3type)
structure pointed to by
.IR res .
.P
The
.BR timespec_getres ()
function stores the resolution of times retrieved by
.BR timespec_get ()
with the specified time base in the
.BR timespec (3type)
structure pointed to by
.IR tp ,
if
.I tp
is non-NULL.
For a particular time base,
the resolution is constant for the lifetime of the calling process.
.P
The time base
.I base
is one of the following:
.TP
.B TIME_UTC
A system-wide time base that measures
real (i.e., wall-clock) time.
The time and resolution in this time base
are the same as those retrieved by
.I clock_gettime(CLOCK_REALTIME,\~res)
and
.IR clock_getres(CLOCK_REALTIME,\~tp) ,
respectively.
.TP
.B TIME_MONOTONIC
A time base that measures
time since an unspecified point in the past,
where the time within a process will not decrease
even if the system's real time clock is set or adjusted.
The time and resolution in this time base
are the same as those retrieved by
.I clock_gettime(CLOCK_MONOTONIC,\~res)
and
.IR clock_getres(CLOCK_MONOTONIC,\~tp) ,
respectively.
.TP
.B TIME_ACTIVE
A process-specific time base that measures
CPU time consumed by
the calling process.
The time and resolution in this time base
are the same as those retrieved by
.I clock_gettime(CLOCK_PROCESS_CPUTIME_ID,\~res)
and
.IR clock_getres(CLOCK_PROCESS_CPUTIME_ID,\~tp) ,
respectively.
.TP
.B TIME_THREAD_ACTIVE
A thread-specific time base that measures
CPU time consumed by
the calling thread.
The time and resolution in this time base
are the same as those retrieved by
.I clock_gettime(CLOCK_THREAD_CPUTIME_ID,\~res)
and
.IR clock_getres(CLOCK_THREAD_CPUTIME_ID,\~tp) ,
respectively.
.SH RETURN VALUE
.BR timespec_get ()
returns the nonzero
.I base
if it is a supported time base
and the current time was successfully retrieved, or 0 otherwise.
.P
.BR timespec_getres ()
returns the nonzero
.I base
if it is a supported time base, or 0 otherwise.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR timespec_get (),
.BR timespec_getres ()
T}	Thread safety	MT-Safe
.TE
.SH STANDARDS
.TP
.BR timespec_get ()
C23, POSIX.1-2024.
.TQ
.B TIME_UTC
C23 (though ISO C doesn't specify the time epoch),
POSIX.1-2024.
.TP
.BR timespec_getres ()
.TQ
.B TIME_MONOTONIC
.TQ
.B TIME_ACTIVE
.TQ
.B TIME_THREAD_ACTIVE
C23.
.SH HISTORY
.TP
.BR timespec_get ()
.TQ
.B TIME_UTC
C11, POSIX.1-2024, glibc 2.16, musl 1.1.10.
.TP
.BR timespec_getres ()
C23, glibc 2.34.
.TP
.B TIME_MONOTONIC
.TQ
.B TIME_ACTIVE
.TQ
.B TIME_THREAD_ACTIVE
C23, glibc 2.43.
.SH SEE ALSO
.BR clock_gettime (2),
.BR clock_getres (2)