sgetmask(2)

✨ sgetmask — manipulation of signal mask (obsolete) ✨

okay bestie, welcome to the sgetmask(2) page, aka the System Calls Manual's most "grandma keeps emailing me" era entry 💀 it's the sgetmask and ssetmask duo and they are, and I cannot stress this enough, obsolete.

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💖 LIBRARY 💖

Standard C library (libc, -lc) 🫶

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🦋 SYNOPSIS 🦋

#include <sys/syscall.h>      /* Definition of SYS_* constants */
#include <unistd.h>

[[deprecated]] long syscall(SYS_sgetmask, void);
[[deprecated]] long syscall(SYS_ssetmask, long newmask);

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🌸 DESCRIPTION 🌸

So here's the tea, and the tea is piping hot: these system calls are obsolete. Do not use them. Use sigprocmask(2) instead, no cap. 🙅♀️

sgetmask() returns the signal mask of the calling process. that's it, that's the whole vibe. ✨

ssetmask() sets the signal mask of the calling process to the value given in newmask. and it hands you back the previous signal mask, like a little souvenir 🎀

the signal masks these two deal with are just plain bit masks — unlike the sigset_t that sigprocmask(2) uses. if you wanna create and inspect these masks, use sigmask(3). that's the whole toolset, bestie 🔧

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👑 RETURN VALUE 👑

sgetmask() always successfully returns the signal mask. always. it has never known failure. it simply returns. 🌈

ssetmask() always succeeds too, and returns the previous signal mask. iconic behaviour, honestly.

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💅 ERRORS 💅

the errors section is empty because these system calls always succeed. yes literally. they have zero toxic traits and zero failure modes. not one error in the building. 💀✨

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⭐ STANDARDS ⭐

Linux. periodt. 🐧

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🕰️ HISTORY 🕰️

since Linux 3.16, support for these system calls is optional, and whether you get them depends on whether the kernel was built with the CONFIG_SGETMASK_SYSCALL option. so it's giving "available, but only if the kernel said yes" 🙈

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📝 NOTES 📝

• these system calls are unaware of signal numbers greater than 31 (i.e., real-time signals). they simply do not perceive them. not their department. 🚫
• these system calls do not exist on x86-64. nope. gone. not invited to the party. 😭
• it is not possible to block SIGSTOP or SIGKILL. some things just cannot be stopped, and those two are them. 🔥

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🔍 SEE ALSO 🔍

• sigprocmask(2)
• signal(7)

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real talk bestie: if you're here looking for a cute signal-mask solution, you're in the wrong aisle. go to sigprocmask(2). this page is a museum exhibit. 🏛️

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okay that's the whole page!! mwah 💋 this was Linux man-pages 6.20, dated 2026-02-08, and yes, the sgetmask(2) girlies ate, even if the kernel devs have been trying to retire them since forever 🫶✨