---
name: "pthread_sigqueue"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/pthread_sigqueue"
---

# pthread\_sigqueue(3)

queue a signal to a specified thread

## NAME

**pthread\_sigqueue** – queue a signal to a specified thread

## LIBRARY

POSIX Threads Library (libpthread, -lpthread)

## SYNOPSIS

**#include \<pthread.h\>**

**#include \<signal.h\>**

*int*\

**pthread\_sigqueue**(*pthread\_t thread*, *int sig*, *const union sigval value*);

## DESCRIPTION

The **pthread\_queue**() function queues a signal, specified by *sig*, to a thread, specified by *thread*. If *sig* is 0, error checking is performed, but no signal is actually sent. The *value* is queued together with the signal, and becomes available in *siginfo\_t* data passed to the signal handler.

The **pthread\_sigqueue** function is similar to [sigqueue(2)](/sigqueue/2.md), but targets a thread in the current process instead of a process. See [sigqueue(2)](/sigqueue/2.md) for details about signal queueing and delivery selection.

## RETURN VALUES

If successful, **pthread\_sigqueue**() returns 0. Otherwise, an error number is returned.

## ERRORS

The **pthread\_sigqueue**() function will fail if:

- \[EAGAIN\]

  No resources are available to queue the signal. The current process has already queued {SIGQUEUE\_MAX} signals that are still pending, or a system-wide resource limit has been exceeded.

- \[ESRCH\]

  *thread* is an invalid thread ID.

- \[EINVAL\]

  *sig* is an invalid or unsupported signal number.

## SEE ALSO

[sigqueue(2)](/sigqueue/2.md)

## STANDARDS

The **pthread\_sigqueue**() function is a FreeBSD extension. An identical function with the same semantic is available in other operating systems.