ioctl_tty(2)

💅 ioctl_tty — bestie edition 💅

okay so this is page ioctl_tty from section 2 (System Calls Manual) of the Linux man-pages, and it's literally the master list of terminal/serial ioctls. buckle up 🎀

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✨ NAME ✨

ioctl_tty — ioctls for terminals and serial lines. that's it, that's the whole vibe. 💖

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📚 LIBRARY 📚

Standard C library (libc, -lc). the classic. the icon. 🫶

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🌸 SYNOPSIS 🌸

#include <asm/termbits.h>  /* Definition of constants */
#include <sys/ioctl.h>

int ioctl(int fd, int op, ...);

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🦋 DESCRIPTION 🦋

so the ioctl(2) call, when you point it at terminals and serial ports, will accept a truly unhinged number of possible operation arguments. like, so many. the menu is huge.

Most of them want a third argument, and the type of that argument varies depending on which op you picked — this page calls it argp or arg because naming things is hard. 💀

bestie, real talk: use of ioctl() makes for nonportable programs. Use the POSIX interface described in termios(7) whenever possible. not me being dramatic, that's just the truth of it. 🙈

Get and set terminal attributes

the "get the settings / set the settings" crew. all of these have their own pages:

• TCGETS(2const)
• TCSETS(2const)
• TCSETSW(2const)
• TCSETSF(2const)

the twos, which are the same energy but different:

• TCGETS2(2const)
• TCSETS2(2const)
• TCSETSW2(2const)
• TCSETSF2(2const)

and the A-squad, the legacy little guys:

• TCGETA(2const)
• TCSETA(2const)
• TCSETAW(2const)
• TCSETAF(2const)

Locking the termios structure

keep your hands off my settings, periodt. 🔒

• TIOCGLCKTRMIOS(2const)
• TIOCSLCKTRMIOS(2const)

Get and set window size

because how big is the window, truly. 📐

• TIOCGWINSZ(2const)
• TIOCSWINSZ(2const)

Sending a break

sent a break, hope they text back. 😭

• TCSBRK(2const)
• TCSBRKP(2const)
• TIOCSBRK(2const)
• TIOCCBRK(2const)

Software flow control

• TCXONC(2const)

Buffer count and flushing

how much is in the buffer, and also get rid of it. two completely different moods, both iconic.

• FIONREAD(2const)
• TIOCINQ(2const)
• TIOCOUTQ(2const)
• TCFLSH(2const)
• TIOCSERGETLSR(2const)

Faking input

she's lying but make it syscall 💅

• TIOCSTI(2const)

Redirecting console output

• TIOCCONS(2const)

Controlling terminal

who's your controlling terminal? main character energy only. 👑

• TIOCSCTTY(2const)
• TIOCNOTTY(2const)

Process group and session ID

• TIOCGPGRP(2const)
• TIOCSPGRP(2const)
• TIOCGSID(2const)

Exclusive mode

no sharing. none. it's giving only child. 🌟

• TIOCEXCL(2const)
• TIOCGEXCL(2const)
• TIOCNXCL(2const)

Line discipline

• TIOCGETD(2const)
• TIOCSETD(2const)

Pseudoterminal ioctls

the pty girlies know ✨

• TIOCPKT(2const)
• TIOCGPKT(2const)
• TIOCSPTLCK(2const)
• TIOCGPTLCK(2const)
• TIOCGPTPEER(2const)

Modem control

• TIOCMGET(2const)
• TIOCMSET(2const)
• TIOCMBIC(2const)
• TIOCMBIS(2const)
• TIOCMIWAIT(2const)
• TIOCGICOUNT(2const)

Marking a line as local

• TIOCGSOFTCAR(2const)
• TIOCSSOFTCAR(2const)

Linux-specific

For the TIOCLINUX(2const) ioctl, see ioctl_console(2). it lives over there, go say hi 🐧

Kernel debugging

• TIOCTTYGSTRUCT(2const)

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🎀 RETURN VALUE 🎀

• on glow-up (success): 0 is returned ✨
• on flop (error): -1 is returned, and errno is set to indicate the error 💀

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🌈 SEE ALSO 🌈

ioctl(2), ldattach(8), ioctl_console(2), termios(7), pty(7)

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and that's the whole page, bestie, no cap 🫶 this was Linux man-pages 6.20, dated 2026-07-02, and honestly? she ate. mwah 💋