sys_sigprocmask(9)

💅 sys_sigprocmask(9) — the Kernel API Manual, section 9, bestie ✨

Okay so bestie, pull up a chair, because this one is literally the "look at your blocked signals and/or change them" syscall 💖. It lives in the Kernel API Manual, section 9, and no cap, it's giving classic signal-mask energy.

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🌸 NAME 🌸

sys_sigprocmask — examine and change blocked signals 🎀

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✨ SYNOPSIS ✨

long sys_sigprocmask (int how , old_sigset_t __user * nset ,
old_sigset_t __user * oset );

Yes queen, three arguments, all spelled out exactly like that — how, nset, oset 💅

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🦋 ARGUMENTS 🦋

• how — tells the kernel whether we're adding signals, removing signals, or setting the whole mask outright. Basically the vibe of the operation 🔥
• nset — the signals to add or remove — but only if it's non-null, bestie 🙈
• oset — the previous value of the signal mask, handed back to you if it's non-null 💖

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👑 DESCRIPTION 👑

So here's the tea 🍓: some platforms have their own version of this bad boy with special arguments, and others only support sys_rt_sigprocmask. That's it, that's the whole description — no extra lore, I'm not gonna invent any 😭

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🌈 SEE ALSO 🌈

The kernel file ./kernel/signal.c is the main character here, and it comes with a whole friend group of signal/jobctl/trap icons ✨:

• task_set_jobctl_pending(9)
• task_clear_jobctl_trapping(9)
• task_clear_jobctl_pending(9)
• task_participate_group_stop(9)
• ptrace_trap_notify(9)
• force_sig_seccomp(9)
• do_notify_parent_cldstop(9)
• do_signal_stop(9)
• do_jobctl_trap(9)
• do_freezer_trap(9)
• signal_delivered(9)
• sys_restart_syscall(9)
• set_current_blocked(9)
• sys_rt_sigprocmask(9)
• sys_rt_sigpending(9)
• copy_siginfo_to_external32(9)
• do_sigtimedwait(9)
• sys_rt_sigtimedwait(9)
• sys_kill(9)
• sys_pidfd_send_signal(9)
• sys_tgkill(9)
• sys_tkill(9)
• sys_rt_sigqueueinfo(9)
• sys_sigpending(9)
• sys_rt_sigaction(9)
• sys_rt_sigsuspend(9)

All 27 of them, exactly as listed, no skipping, no cap 🫶

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Heads up, bestie: the man page doesn't promise anything beyond what's written above — so don't go reading extra behaviour into it, mwah 💜

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And that's a wrap, babes 🎀 — this page came straight out of ./kernel and it's dated October 2026, so go forth and signal-mask responsibly, iykyk 💅✨🦋