time_t(3type)

💖 time_t(3type) — bestie, let's talk about time 💖

okay so this whole page lives in section 3type of the manual, and it's your girl's guide to the three little integer types that hold time 👑 no cap.

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✨ NAME ✨

time_t, suseconds_t, useconds_t — the integer time squad 🕰️

📚 LIBRARY 📚

Standard C library (libc) — the classic, the icon, the one you already have 💅

🧚 SYNOPSIS 🧚

#include <time.h>

typedef /* ... */  time_t;

#include <sys/types.h>

typedef /* ... */  suseconds_t;
typedef /* ... */  useconds_t;

🌸 DESCRIPTION 🌸

so here's the lineup, one by one:

• time_t — this one holds time in seconds. per POSIX it's an integer type of at least 64 bits ⏳
• suseconds_t — this one holds time in microseconds. it's a signed integer type, and it can store values at least in the range [-1, 1000000] 🫶
• useconds_t — also time in microseconds, but this one is unsigned, and it can store values at least in the range [0, 1000000] ✨

🎀 STANDARDS 🎀

• time_t — C11, POSIX.1-2024. certified ✅
• suseconds_t — POSIX.1-2024. also certified ✅
• useconds_t — None. not certified at all, it's giving ✨mystery✨

🦋 HISTORY 🦋

• time_t — C89, POSIX.1-1988. she's been here since forever, a true OG 👑
• suseconds_t — SUSv2, POSIX.1-2001 XSI, POSIX.1-2024.
• useconds_t — SUSv1, POSIX.1-2001 XSI. Removed in POSIX.1-2008 💀 rip bestie

🌈 Header files 🌈

<sched.h> defines time_t since POSIX.1-2008. that's the lore 🫶

⏰ time_t ⏰

POSIX.1-2024 requires that the width of time_t is at least 64 bits — but some systems are still out here using 32 bits by default 😭 not the 2038 vibe, bestie.

💅 NOTES 💅

On some architectures, the width of time_t can be controlled with the feature test macro _TIME_BITS. go see feature_test_macros(7) if you want the tea 🍓

the following headers also provide time_t: <sched.h>, <sys/msg.h>, <sys/select.h>, <sys/sem.h>, <sys/shm.h>, <sys/stat.h>, <sys/time.h>, <sys/types.h>, and <utime.h>. it's everywhere, she gets around 💖

the following headers also provide suseconds_t: <sys/select.h> and <sys/time.h>.

the following headers also provided useconds_t: <unistd.h>. note the past tense — provided 🙈

👀 SEE ALSO 👀

stime(2), time(2), ctime(3), difftime(3), usleep(3), timeval(3type)

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and that's the whole page, bestie!! 🌟 this came from Linux man-pages 6.20, dated 2026-02-08, on the time_t(3type) page. go forth and store your seconds correctly 💜✨ periodt.