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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.
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.
Configurable limits
When you're trying to determine your system's limits, you can get the values of configurable limits, special read-only variables that store system information.

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.
    - 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.
      - Configurable limits
        When you're trying to determine your system's limits, you can get the values of configurable limits, special read-only variables that store system information.
      - Filesystem limits
        Under the QNX OS, filesystems aren't part of the kernel or core operating system; they're provided by separately loadable processes or libraries.
      - Other system limits
    - 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 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.
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.

Configurable limits

QNX SDP8.0User's GuideUser

When you're trying to determine your system's limits, you can get the values of configurable limits, special read-only variables that store system information.

Note:

QNX OS also supports configuration strings, which are similar to, and frequently used in conjunction with, environment variables. For more information, see the Configuring Your Environment chapter.

You can use the POSIX getconf utility to get the value of a configurable limit or a configuration string. Since getconf is a POSIX utility, scripts that use it instead of hard-coded QNX OS-specific limits can adapt to other POSIX environments.

Some configurable limits are associated with a path; their names start with _PC_. When you get the value of these limits, you must provide the path (see Filesystem limits, below). For example, to get the maximum length of the filename, type:

getconf _PC_NAME_MAX pathname

Other limits are associated with the entire system; their names start with _SC_. You don't have to provide a path when you get their values. For example, to get the maximum number of files that a process can have open, type:

getconf _SC_OPEN_MAX

In general, you can't change the value of the configurable limits—they're called configurable because the system can set them.

The QNX OS libraries provide various functions that you can use in a program to work with configurable limits:

pathconf(): Get the value of a configurable limit that's associated with a path.
sysconf(): Get the value of a limit for the entire system.
setrlimit(): Change the value of certain limits. For example, you can use this function to limit the number of files that a process can open; this limit also depends on the value of the -F option to procnto.

Page updated: August 09, 2024