Home
QNX Software Development Platform
OS Components
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.
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.
What does a user account do?
A user account associates a textual user name with a numeric user ID and group ID, a login password, a user's full name, a home directory, and a login shell. This data is stored in the /etc/passwd and /etc/shadow files, where it's accessed by login utilities as well as by other applications that need user-account information.

QNX Momentics IDE User's Guide
QNX Software Development Platform
- Quickstart Guide
- System Architecture
  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
- OS Components
  - 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.
  - 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
  - QNX Helpers Developer's Guide
    These libraries provide QNX helpers, including helpers that assist with logging, string conversion, and number and type sizes.
  - SMMUMAN User's Guide
  - SPI Framework Technote
  - 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.
      - What does a user account do?
        A user account associates a textual user name with a numeric user ID and group ID, a login password, a user's full name, a home directory, and a login shell. This data is stored in the /etc/passwd and /etc/shadow files, where it's accessed by login utilities as well as by other applications that need user-account information.
        User accounts vs user IDs: login, lookup, and permissions
        Once you've logged in, the numeric user ID of your running programs and system resources determines your programs' ability to access resources and perform operations, such as sending signals to other processes. Textual names are used only by utilities and applications that need to convert between names and numeric IDs.
        What happens when you log in?
        You typically start a session on the computer by logging in; the configuration of your account determines what happens then.
      - Account database
        The account database consists of the files (listed with the appropriate access permissions) described in this section.
      - Managing your own account
      - Managing other accounts
        As a system administrator, you need to add and remove user accounts and groups, manage passwords, and troubleshoot users' problems. You must be logged in as root to do this, because other users don't have permission to modify /etc/passwd, /etc/shadow, and /etc/group.
      - Troubleshooting
        Here are some problems you might encounter while working with passwords and user 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.
    - 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 OS applications and systems.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation and explains how to obtain technical support.

What does a user account do?

QNX SDP8.0User's GuideUser

A user account associates a textual user name with a numeric user ID and group ID, a login password, a user's full name, a home directory, and a login shell. This data is stored in the /etc/passwd and /etc/shadow files, where it's accessed by login utilities as well as by other applications that need user-account information.

Note: User names and passwords are case-sensitive.

User accounts let:

users log in with a user name and password, starting a session under their user ID and group ID
users create their own login environments
applications determine the user name and account information relating to a user ID and group ID if they're defined in /etc/passwd and /etc/group (e.g., ls -l displays the names—not the IDs—of the user and group who own each file)
utilities and applications accept user names as input as an alternative to numeric user IDs
shells expand ~username paths into actual pathnames, based on users' home directory information stored in their accounts

Groups are used to convey similar permissions to groups of users on the system. Entries in /etc/passwd and /etc/group define group membership, while the group ID of a running program and the group ownership and permission settings of individual files and directories determine the file permission granted to a group member.

When you log in, you're in the group specified in /etc/passwd. You can switch to another of your groups by using the newgrp utility.

Page updated: May 17, 2024