---
name: "pthread_condattr_getclock"
section: "3p"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/pthread_condattr_getclock/3p"
---

# pthread\_condattr\_getclock(3p)

get and set the clock selection condition variable attribute

## PROLOG

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

## NAME

pthread\_condattr\_getclock, pthread\_condattr\_setclock — get and set the clock selection condition variable attribute

## SYNOPSIS

```
#include <pthread.h>
```

int pthread\_condattr\_getclock(const pthread\_condattr\_t \*restrict *attr*,\
     clockid\_t \*restrict *clock\_id*); int pthread\_condattr\_setclock(pthread\_condattr\_t \**attr*,\
     clockid\_t *clock\_id*);

## DESCRIPTION

The *pthread\_condattr\_getclock*() function shall obtain the value of the *clock* attribute from the attributes object referenced by *attr*.

The *pthread\_condattr\_setclock*() function shall set the *clock* attribute in an initialized attributes object referenced by *attr*. If *pthread\_condattr\_setclock*() is called with a *clock\_id* argument that refers to a CPU-time clock, the call shall fail.

The *clock* attribute is the clock ID of the clock that shall be used to measure the timeout service of *pthread\_cond\_timedwait*(). The default value of the *clock* attribute shall refer to the system clock.

The behavior is undefined if the value specified by the *attr* argument to *pthread\_condattr\_getclock*() or *pthread\_condattr\_setclock*() does not refer to an initialized condition variable attributes object.

## RETURN VALUE

If successful, the *pthread\_condattr\_getclock*() function shall return zero and store the value of the clock attribute of *attr* into the object referenced by the *clock\_id* argument. Otherwise, an error number shall be returned to indicate the error.

If successful, the *pthread\_condattr\_setclock*() function shall return zero; otherwise, an error number shall be returned to indicate the error.

## ERRORS

The *pthread\_condattr\_setclock*() function may fail if:

- **EINVAL**

  The value specified by *clock\_id* does not refer to a known clock, or is a CPU-time clock.

These functions shall not return an error code of **\[EINTR\]**.

*The following sections are informative.*

## EXAMPLES

None.

## APPLICATION USAGE

None.

## RATIONALE

If an implementation detects that the value specified by the *attr* argument to *pthread\_condattr\_getclock*() or *pthread\_condattr\_setclock*() does not refer to an initialized condition variable attributes object, it is recommended that the function should fail and report an **\[EINVAL\]** error.

## FUTURE DIRECTIONS

None.

## SEE ALSO

*pthread\_cond\_destroy()*, *pthread\_cond\_timedwait()*, *pthread\_condattr\_destroy()*, *pthread\_condattr\_getpshared()*, *pthread\_create()*, *pthread\_mutex\_destroy()*

The Base Definitions volume of POSIX.1‐2017, ***\<pthread.h\>***

## COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting\_bugs.html .