timespec_get(3)

💖 timespec_get(3) 💖

okay bestie, welcome to the timespec_get page from the Library Functions Manual — yes this is a section 3 manual page and yes it's about the ISO C interface to clock and time functions. grab a boba, we're doing time today 🕐✨

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🌸 NAME 🌸

timespec_get, timespec_getres — the ISO C interface to clock and time functions. iykyk, this is the glow-up of getting the time but make it standardised 💅

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📚 LIBRARY 📚

Standard C library, aka libc, aka link it with -lc. she's everywhere, she's iconic, she's already in your binary 💖

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✨ SYNOPSIS ✨

#include <time.h>

int timespec_get(struct timespec *res, int base);
int timespec_getres(struct timespec *tp, int base);

🎀 Feature Test Macro Requirements for glibc (see feature_test_macros(7)) 🎀

okay so glibc is picky about which macros you define before you get to play with these, bestie, so listen up:

• timespec_get(), TIME_UTC — you gotta have _ISOC11_SOURCE 💫
• timespec_getres(), TIME_MONOTONIC, TIME_ACTIVE, TIME_THREAD_ACTIVE — you gotta have _ISOC23_SOURCE 💫

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🦋 DESCRIPTION 🦋

so, timespec_get() stores the current time — based on the time base you picked — into the timespec(3type) structure that res points at. it literally hands you the time. no cap 🫶

and timespec_getres()? she stores the resolution of times retrieved by timespec_get() with that specified time base into the timespec(3type) structure that tp points at — but only if tp is non-NULL. like, if tp is NULL she just… doesn't. 🙈 also, for any particular time base, that resolution is constant for the lifetime of the calling process. it does not change on you. periodt.

The time base base is one of these iconic options:

• TIME_UTC — a system-wide time base measuring real time, aka wall-clock time. the time and resolution in this base are exactly the same as what you'd get from clock_gettime(CLOCK_REALTIME, res) and clock_getres(CLOCK_REALTIME, tp). same energy, different font 💖
• TIME_MONOTONIC — a time base that measures time since some unspecified point in the past, and the time within a process will never decrease, even if the system's real time clock gets set or adjusted. she only goes forward, main character energy. the time and resolution here are the same as clock_gettime(CLOCK_MONOTONIC, res) and clock_getres(CLOCK_MONOTONIC, tp) ✨
• TIME_ACTIVE — a process-specific time base measuring CPU time consumed by the calling process. the time and resolution are the same as clock_gettime(CLOCK_PROCESS_CPUTIME_ID, res) and clock_getres(CLOCK_PROCESS_CPUTIME_ID, tp) 🔥
• TIME_THREAD_ACTIVE — a thread-specific time base measuring CPU time consumed by the calling thread. the time and resolution match clock_gettime(CLOCK_THREAD_CPUTIME_ID, res) and clock_getres(CLOCK_THREAD_CPUTIME_ID, tp) 🌈

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🫶 RETURN VALUE 🫶

• timespec_get() returns the nonzero base if it's a supported time base and the current time was successfully retrieved. otherwise it returns 0. that's it, that's the vibe check 💀
• timespec_getres() returns the nonzero base if it's a supported time base, or 0 otherwise.

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💅 ATTRIBUTES 💅

For an explanation of the terms used in this section, see attributes(7).

• Interface: timespec_get(), timespec_getres()
• Attribute: Thread safety
• Value: MT-Safe

(that means she's safe to share with all your threads. no drama, no races, we love to see it 👑)

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🌟 STANDARDS 🌟

• timespec_get() — C23, POSIX.1-2024.
• TIME_UTC — C23 (though ISO C doesn't specify the time epoch, so don't come for her), POSIX.1-2024.
• timespec_getres() — C23.
• TIME_MONOTONIC — C23.
• TIME_ACTIVE — C23.
• TIME_THREAD_ACTIVE — C23.

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📜 HISTORY 📜

• timespec_get() — C11, POSIX.1-2024, glibc 2.16, musl 1.1.10.
• TIME_UTC — C11, POSIX.1-2024, glibc 2.16, musl 1.1.10.
• timespec_getres() — C23, glibc 2.34.
• TIME_MONOTONIC — C23, glibc 2.43.
• TIME_ACTIVE — C23, glibc 2.43.
• TIME_THREAD_ACTIVE — C23, glibc 2.43.

(the girls that came in 2.43 are the new kids and they're already slaying 🧚)

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👀 SEE ALSO 👀

• clock_gettime(2)
• clock_getres(2)

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and that's the whole page bestie, go forth and timestamp responsibly 💖✨

Linux man-pages 6.20 · 2026-02-11 — mwah, kiss kiss, this page was brought to you by that exact version and date, no cap 🎀💜