Home
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
Utilities & Libraries
C Library Reference
U

QNX Momentics IDE User's Guide
This User's Guide describes version 8.0 of the Integrated Development Environment (IDE) that's part of the QNX Tool Suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
- Quickstart Guide
- System Architecture
  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
- OS Components & Operations
- Graphics
- Programming
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX OS system and developers who want to create a QNX OS resource manager free from vulnerabilities.
- Utilities & Libraries
  - C Library Reference
    - What's in a Function Description?
    - Manifests
    - Character Sets
    - A
    - B
    - C
    - D
    - E
    - F
    - G
    - H
    - I
    - J
    - K
    - L
    - M
    - N
    - O
    - P
    - Q
    - R
    - S
    - T
    - U
      - ualarm()
        Schedule an alarm
      - umask()
        Set the file-mode creation mask for the process
      - umount()
        Unmount a filesystem
      - UNALIGNED_PUT16()
        Write a misaligned 16-bit value safely
      - UNALIGNED_PUT32()
        Write a misaligned 32-bit value safely
      - UNALIGNED_PUT64()
        Write a misaligned 64-bit value safely
      - UNALIGNED_RET16()
        Access a misaligned 16-bit value safely
      - UNALIGNED_RET32()
        Access a misaligned 32-bit value safely
      - UNALIGNED_RET64()
        Access a misaligned 64-bit value safely
      - uname()
        Get information about the operating system
      - ungetc()
        Push a character back onto an input stream
      - ungetwc()
        Push a wide character back onto an input stream
      - _unregister_ioctl_handler()
        Unregister an I/O control handler
      - unlink()
        Remove a link to a file
      - unlinkat()
        Remove a link to a file at a given location
      - unlockpt()
        Unlock a pseudo-terminal master/slave pair
      - unsetenv()
        Remove an environment variable
      - usleep()
        Suspend a thread for a given number of microseconds
      - utime()
        Set the modification time for a file or directory
      - utimensat()
        Set the access and modification times for a file
      - utimes()
        Set a file's access and modification times
      - utmp
        Entry in a user-information file
      - utmpname()
        Specify a different user information file
    - V
    - W
    - X
    - Y
    - Z
    - Full Safety Information
    - Glossary
  - Devctl and Ioctl Commands
  - JSON Library Reference
  - PAM Reference
  - QNX Helpers Developer's Guide
    These libraries provide QNX helpers, including helpers that assist with logging, string conversion, and number and type sizes.
  - SPI Framework Technote
  - QNX Cryptography Library
    The QNX Cryptography Library (qcrypto) is a flexible cryptography framework that allows you to choose which cryptography provider responds to requests on a per-process basis.
  - QNX devcrypto Service
  - Utilities Reference
  - WPA Control Interface Reference
    This document provides a reference for the Wi-Fi Protected Access (WPA) control interface, which provides a C API for the WPA/IEEE 802.11i protocols in Wi-Fi client stations. Application developers who want to control WPA operations and get associated status and event data should read this reference.
- Migrating to QNX OS 8.0
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX OS in the Amazon cloud environment.
QNX Toolkit for Visual Studio Code
This User's Guide describes the QNX^® Toolkit for Visual Studio Code. The guide introduces you to the QNX Toolkit by explaining the QNX development environment and how to build, run, and debug your QNX^® Operating System (OS) applications and systems.
QNX Hypervisor User's Guide
This User's Guide explains the QNX hypervisor architecture and provides instructions for installing and running a QNX Hypervisor system, changing system components and configuration, and using hypervisor features such as virtual devices (vdevs).
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation, explains how to obtain technical support, and provides some information about licensing.

U

QNX SDP8.0C Library ReferenceAPIDeveloper

The functions, macros, and data structures in the C library are described here in alphabetical order.

A ¦ B ¦ C ¦ D ¦ E ¦ F ¦ G ¦ H ¦ I ¦ J ¦ K ¦ L ¦ M ¦ N ¦ O ¦ P ¦ Q ¦ R ¦ S ¦ T ¦ U ¦ V ¦ W ¦ X ¦ Y ¦ Z

The following are described elsewhere:


For information about:	See:
UDP	FreeBSD documentation (https://man.freebsd.org/cgi/man.cgi?query=udp&sektion=4&manpath=FreeBSD+13.5-RELEASE+and+Ports)
UNIX	FreeBSD documentation (https://man.freebsd.org/cgi/man.cgi?query=unix&sektion=4&manpath=FreeBSD+13.5-RELEASE+and+Ports)

This chapter describes the API components whose names begin with U.

Page updated: August 11, 2025