tcsendbreak(3)

✨ tcsendbreak(3) ✨

okay bestie, so this is a page from the Library Functions Manual — the tcsendbreak one, and it's genuinely the most "send vibes into the void" function in termios. let's get into it 💅

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🌸 NAME 🌸

tcsendbreak — send a continuous stream of zero-valued bits

like… it just sends a lil stream of zeroes. that's the whole personality. periodt 🎀

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🦋 LIBRARY 🦋

Standard C library (libc, -lc)

yep, plain old libc, she's a classic 👑

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✨ SYNOPSIS ✨

#include <termios.h>

int tcsendbreak(int fd, int duration);

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💖 DESCRIPTION 💖

so tcsendbreak() transmits a continuous stream of zero-valued bits for a specific duration — but only if the terminal is using asynchronous serial data transmission. like, she checks the vibe first 🌈

If duration is zero, it transmits zero-valued bits for at least 0.25 seconds, and not more than 0.5 seconds. a cute lil window, we love her 🫶

If duration is not zero, it sends zero-valued bits for some implementation-defined length of time. translation: every system does its own thing here, it's giving chaos, see the VERSIONS section if you want the tea 😭

If the terminal is not using asynchronous serial data transmission, tcsendbreak() returns without taking any action. she simply does nothing. no drama, no break, just vibes going nowhere 💀

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🔥 RETURN VALUE 🔥

• 0 — on success. slay ✨
• -1 — on failure, and it sets errno to indicate the error 😭

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🧚 ATTRIBUTES 🧚

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

• Interface: tcsendbreak()
• Attribute: Thread safety
• Value: MT-Safe 👑

like yeah she's MT-Safe no cap, go off bestie

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🌈 VERSIONS 🌈

okay so the effect of a nonzero duration with tcsendbreak() varies a lot. here's the receipts, no guessing, all facts:

• SunOS specifies a break of duration * N seconds, where N is at least 0.25, and not more than 0.5.
• Linux, AIX, DU, Tru64 send a break of duration milliseconds.
• FreeBSD and NetBSD and HP-UX and MacOS ignore the value of duration entirely. literally just ignoring her, rude 💀
• Under Solaris and UnixWare, tcsendbreak() with nonzero duration behaves like tcdrain(3).

so yeah bestie, if you're porting code with a nonzero duration and expecting one specific behaviour… you're gonna have a bad time 😭

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👑 STANDARDS 👑

POSIX.1-2008.

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🎀 HISTORY 🎀

POSIX.1-2001.

she's been around. an icon. a legend 💜

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💜 SEE ALSO 💜

tcdrain(3), tcflush(3), tcflow(3), termios(7)

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ngl that's the whole page bestie, go forth and send your zero bits 🌸

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that's a wrap 🫶 this was Linux man-pages 6.20, dated 2026-07-02, and yes the page is literally called tcsendbreak(3) — ily, go read termios(7) next, it's giving main character energy ⭐