---
name: "rt_sigsuspend"
section: "2"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/sigsuspend"
---

# rt\_sigsuspend(2)

wait for a signal

Part of [sigsuspend(2)](/sigsuspend/2.md).

## NAME

sigsuspend, rt\_sigsuspend - wait for a signal

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <signal.h>
```

**int sigsuspend(const sigset\_t \****mask***);**

Feature Test Macro Requirements for glibc (see [**feature\_test\_macros**(7)](/feature_test_macros/7.md)):

**sigsuspend**():

```
    _POSIX_C_SOURCE
```

## DESCRIPTION

**sigsuspend**() temporarily replaces the signal mask of the calling thread with the mask given by *mask* and then suspends the thread until delivery of a signal whose action is to invoke a signal handler or to terminate a process.

If the signal terminates the process, then **sigsuspend**() does not return. If the signal is caught, then **sigsuspend**() returns after the signal handler returns, and the signal mask is restored to the state before the call to **sigsuspend**().

It is not possible to block **SIGKILL** or **SIGSTOP**; specifying these signals in *mask*, has no effect on the thread's signal mask.

## RETURN VALUE

**sigsuspend**() always returns -1, with *errno* set to indicate the error (normally, **EINTR**).

## ERRORS

- **EFAULT**

  *mask* points to memory which is not a valid part of the process address space.

- **EINTR**

  The call was interrupted by a signal; [**signal**(7)](/signal/7.md).

## STANDARDS

POSIX.1-2024.

## HISTORY

POSIX.1-2001.

### C library/kernel differences

The original Linux system call was named **sigsuspend**(). However, with the addition of real-time signals in Linux 2.2, the fixed-size, 32-bit *sigset\_t* type supported by that system call was no longer fit for purpose. Consequently, a new system call, **rt\_sigsuspend**(), was added to support an enlarged *sigset\_t* type. The new system call takes a second argument, *size\_t sigsetsize*, which specifies the size in bytes of the signal set in *mask*. This argument is currently required to have the value *sizeof(sigset\_t)* (or the error **EINVAL** results). The glibc **sigsuspend**() wrapper function hides these details from us, transparently calling **rt\_sigsuspend**() when the kernel provides it.

## NOTES

Normally, **sigsuspend**() is used in conjunction with [**sigprocmask**(2)](/sigprocmask/2.md) in order to prevent delivery of a signal during the execution of a critical code section. The caller first blocks the signals with [**sigprocmask**(2)](/sigprocmask/2.md). When the critical code has completed, the caller then waits for the signals by calling **sigsuspend**() with the signal mask that was returned by [**sigprocmask**(2)](/sigprocmask/2.md) (in the *oldset* argument).

See [**sigsetops**(3)](/sigsetops/3.md) for details on manipulating signal sets.

## SEE ALSO

[**kill**(2)](/kill/2.md), [**pause**(2)](/pause/2.md), [**sigaction**(2)](/sigaction/2.md), [**signal**(2)](/signal/2.md), [**sigprocmask**(2)](/sigprocmask/2.md), [**sigwaitinfo**(2)](/sigwaitinfo/2.md), [**sigsetops**(3)](/sigsetops/3.md), [**sigwait**(3)](/sigwait/3.md), [**signal**(7)](/signal/7.md)