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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.
OS Components & Operations
User's Guide
The QNX OS User's Guide is intended for all users of a QNX OS system, from system administrators to end users.
Working with Files
In a QNX OS system, almost everything is a file; devices, data, and even services are all typically represented as files. This lets you work with local and remote resources easily from the command line, or through any program that works with files.
Filenames and pathnames
To access any file or directory, you must specify a pathname, a symbolic name that tells a program where to find a file within the directory hierarchy based at root (/).
Dot and dot-dot directories
Most directories contain two special links, . (dot) and .. (dot dot).

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
  - Boot Optimization Guide
    The Boot Optimization Guide describes techniques you can use to reduce the time from your board's initial power on until you have a fully functional QNX system running on the board.
  - Building Embedded Systems
    The Building Embedded Systems guide is intended for developers who are developing or building BSPs for QNX OS embedded systems.
  - Customizing a BSP
    While QNX provides Board Support Packages (BSPs) for many common platforms and their individual variants, in some cases, you need a BSP for a board that QNX does not provide. If this is the case, you can modify a QNX BSP or develop your own.
  - Device Publishers Developer's Guide
  - High Availability Framework Developer's Guide
  - High-Performance Networking Stack (io-sock) User's Guide
    This guide contains instructions for implementing and using the QNX OS High-Performance Networking Stack and its manager, io-sock.
  - PCI Server User's Guide
  - Performance Tuning User's Guide
  - SMMUMAN User's Guide
  - System Analysis Toolkit (SAT) User's Guide
  - Technotes
  - User's Guide
    The QNX OS User's Guide is intended for all users of a QNX OS system, from system administrators to end users.
    - Getting to Know the OS
      Welcome to the QNX OS!
    - Logging In, Logging Out, and Shutting Down
      QNX OS is a multiuser operating system; it lets multiple users log in and use the system simultaneously, and it protects them from each other through a system of resource ownership and permissions.
    - Managing User Accounts
      This chapter explains how user accounts work, how users can change their password by using the passwd utility, and how system administrators can use the passwd utility and edit account database files to create and maintain users' accounts.
    - Using the Command Line
      Like QNX 4, Unix, and DOS, the QNX OS is based on a command-line interface that you might want or need to use instead of the GUI.
    - Working with Files
      In a QNX OS system, almost everything is a file; devices, data, and even services are all typically represented as files. This lets you work with local and remote resources easily from the command line, or through any program that works with files.
      - Types of files
        QNX OS supports various types of files. The file type gives you a hint about what type of data the file contains and how you should expect the file to behave.
      - Filenames and pathnames
        To access any file or directory, you must specify a pathname, a symbolic name that tells a program where to find a file within the directory hierarchy based at root (/).
        Absolute and relative pathnames
        Dot and dot-dot directories
        Most directories contain two special links, . (dot) and .. (dot dot).
        No drive letters
        Unlike Microsoft Windows, which represents drives as letters that precede pathnames (e.g., C:\), QNX OS represents disk drives as regular directories within the pathname space. Directories that access another filesystem, such as one on a second hard disk partition, are called mountpoints.
        Pathnames that begin with a dot
        When you list the contents of a directory, the ls utility usually hides files and directories whose names begin with a period. Programs precede configuration files and directories with a period to hide them from view. The files (not surprisingly) are called hidden files.
        Extensions
        Filename extensions (.something at the end of a filename) tell programs and users what type of data a file contains.
        Pathname-space mapping
        You may have noticed that we've talked about files and directories appearing in their parent directories, rather than just saying that the parent directories contain these files. This is because in QNX OS, the pathname space is virtual, dictated not just by the filesystem that resides on media mounted at root, but rather by the paths and pathname aliases registered by the process manager.
        Filename rules
        QNX OS supports a variety of filesystems, each of which has different capabilities and rules for valid filenames.
      - Where everything is stored
        The QNX OS operating system doesn't prescribe a specific layout of the filesystem hierarchy, and a system designer is generally free to structure files in a way that fits the goals of the system.
      - File ownership and permissions
        Each file and directory belongs to a specific user ID and group ID, and has a set of permissions (also referred to as modes) associated with it.
      - Filename extensions
        This table lists some common filename extensions used in a QNX OS system.
      - Troubleshooting
        Here are a few problems that you might have with files.
    - Using Editors
      An editor is a utility designed to view and modify files.
    - Configuring Your Environment
      The Building Embedded Systems guide describes what happens when you boot your system, and what you can do to customize it. This chapter describes how you can customize the environment that you get when you log in, and then describes some of the setup you might need to do.
    - Writing Shell Scripts
      Shell scripting, at its most basic, is taking a series of commands you might type at a command line and putting them into a file, so you can reproduce them again at a later date, or run them repeatedly without having to type them over again.
    - Working with Filesystems
      The QNX OS provides a variety of filesystems, so that you can easily access DOS, Linux, as well as native Power-Safe disks.
    - TCP/IP Networking
      The term TCP/IP implies two distinct protocols: TCP and IP. Since these protocols have been used so commonly together, TCP/IP has become a standard terminology in today's Internet. Essentially, TCP/IP refers to network communications where the TCP transport is used to deliver data across IP networks.
    - Backing Up Data
      No matter how reliable your hardware and electrical supply are, or how sure you are that you'll never accidentally erase all your work, it's just common sense to keep backups of your files. Backup strategies differ in ease of use, speed, robustness, and cost.
    - Securing Your System
      Now that more and more computers and other devices are hooked up to insecure networks, security has become a very important issue. The word security can have many meanings, but in a computer context, it generally means preventing unauthorized people from making your computer do things that you don't want it to do.
    - Fine-Tuning Your System
      This chapter describes how you can improve your system's performance.
    - Understanding System Limits
      Resources on a system tend to be finite (alas!), and some are more limited than others. This chapter describes some of the limits on a QNX OS system.
    - Examples
      This appendix includes samples of some of the files described in this guide.
    - Glossary
- 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
- 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.

Dot and dot-dot directories

QNX SDP8.0User's GuideUser

Most directories contain two special links, . (dot) and .. (dot dot).

. (dot): The current directory.
.. (dot dot): The directory that this directory appears in.

So, for example, you could list the contents of the directory above your current working directory by typing:

ls ..

If your current directory is /home/fred/my_apps/favs, you could list the contents of the root directory by typing:

ls ../../../..

but the absolute path (/) is much shorter, and you don't have to figure out how many dot dots you need.

Page updated: March 05, 2025