Rationale: Table of Contents

• A. Rationale for Base Definitions
  • A.1 Introduction
    • A.1.1 Scope
      • Scope of POSIX.1-2024
      • POSIX.1 and the ISO C Standard
      • FIPS Requirements
    • A.1.2 Word Usage
    • A.1.3 Conformance
    • A.1.4 Normative References
    • A.1.5 Change History
    • A.1.6 Terminology
    • conformance document
    • implementation-defined
    • may
    • shall
    • should
    • obsolescent
    • legacy
    • system documentation
    • undefined
    • unspecified
    • macro
    • symbolic name
    • symbolic constant
    • A.1.7 Definitions and Concepts
    • A.1.8 Portability
      • A.1.8.1 Codes
      • A.1.8.2 Margin Code Notation
  • A.2 Conformance
    • A.2.1 Implementation Conformance
      • A.2.1.1 Requirements
      • A.2.1.2 Documentation
      • A.2.1.3 POSIX Conformance
      • A.2.1.4 XSI Conformance
      • A.2.1.5 Option Groups
      • Subprofiling Considerations
      • XSI Option Groups
      • A.2.1.6 Options
    • A.2.2 Application Conformance
      • A.2.2.1 Strictly Conforming POSIX Application
      • A.2.2.2 Conforming POSIX Application
      • A.2.2.3 Conforming POSIX Application Using Extensions
      • A.2.2.4 Strictly Conforming XSI Application
      • A.2.2.5 Conforming XSI Application Using Extensions
    • A.2.3 Language-Dependent Services for the C Programming Language
    • A.2.4 Other Language-Related Specifications
  • A.3 Definitions
    • Alias Name
    • Anonymous Memory Object
    • Application
    • Appropriate Privileges
    • Async-Signal-Safe Function
    • Background Job
    • Base Character*
    • Basename
    • Built-In Utility
    • Byte
    • Character
    • Child Process
    • Clock Tick
    • Code Block
    • Command
    • Column Positions
    • Condition Variable
    • Control Operator
    • Controlling Terminal
    • Core Image
    • CPU Time (Execution Time)
    • Decimal-Point Character
    • Declaration Utility
    • Device Number*
    • Direct I/O
    • Directory
    • Directory Entry (or Hard Link)
    • Display
    • Dot
    • Dot-Dot
    • Dot-Po File
    • Empty Directory
    • Epoch
    • FIFO Special File
    • File
    • File Classes
    • File Descriptor
    • File Lock
    • File Mode
    • Filename
    • File System
    • Foreground Job
    • Graphic Character
    • Group Database
    • Group File*
    • Group ID
    • Group Name
    • Hard Link
    • Historical Implementations*
    • Hole
    • Hosted Implementation*
    • Implementation*
    • Incomplete Pathname*
    • Interactive Device
    • Intrinsic Utility
    • Job
    • Job Control
    • Job ID
    • Joinable Thread
    • Kernel*
    • Library Routine*
    • Link
    • Live Process
    • Live Thread
    • Logical Device*
    • Map
    • Memory-Resident
    • Memory Object*
    • Messages Object
    • Mounted File System*
    • Multi-Threaded Library
    • Multi-Threaded Process
    • Multi-Threaded Program
    • Mutex
    • Name
    • Native Implementation*
    • Negative
    • Nice Value
    • Null Pointer
    • Null Terminator
    • OFD-Owned File Lock
    • Open File Description
    • Option-Argument
    • Orphaned Process Group
    • Page
    • Pathname
    • Passwd File*
    • Parent Directory
    • Pattern
    • Pipe
    • Portable Filename
    • Portable Filename Character Set
    • Portable Messages Object Source File (or Dot-Po File)
    • Positional Parameter
    • Positive
    • Process
    • Process Lifetime
    • Process Termination
    • Process-Owned File Lock
    • Pseudo-Terminal
    • Radix Character (or Decimal-Point Character)
    • Record Lock
    • Regular Built-In Utility (or Regular Built-In)
    • Regular File
    • Root Directory
    • Root File System*
    • Root of a File System*
    • Signal
    • Single-Threaded Process
    • Single-Threaded Program
    • Source Code
    • Sparse File
    • Special Built-In Utility (or Special Built-In)
    • Standard Error
    • Standard Input
    • Standard Output
    • Stream
    • Superuser*
    • Supplementary Group ID
    • Suspended Job
    • Symbolic Constant
    • Symbolic Link
    • Synchronized I/O Data Integrity Completion
    • Synchronously-Generated Signal
    • System Call*
    • System Console
    • System Databases
    • System Process
    • System Reboot
    • Synchronized I/O Data (and File) Integrity Completion
    • Text Domain
    • Text File
    • Thread
    • Thread ID
    • Thread Lifetime
    • Thread Termination
    • Thread-Safe
    • Thread-Specific Data Key
    • User Database
    • User ID
    • User Name
    • Virtual Processor*
    • White Space
    • XSI
    • Zombie Process
    • Zombie Thread
  • A.4 General Concepts
    • A.4.1 Case Insensitive Comparisons
    • A.4.2 Concurrent Execution
    • A.4.3 Default Initialization
    • A.4.4 Directory Operations
    • A.4.5 Directory Protection
    • A.4.6 Extended Security Controls
    • A.4.7 File Access Permissions
    • A.4.8 File Hierarchy
    • A.4.9 Filenames
    • A.4.10 Filename Portability
    • A.4.11 File System Cache
    • A.4.12 File Times Update
    • A.4.13 Host and Network Byte Order
    • A.4.14 Measurement of Execution Time
    • A.4.15 Memory Ordering and Synchronization
      • A.4.15.1 Memory Ordering
      • A.4.15.2 Memory Synchronization
    • A.4.16 Pathname Resolution
    • A.4.17 Process ID Reuse
    • A.4.18 Scheduling Policy
    • A.4.19 Seconds Since the Epoch
    • A.4.20 Semaphore
    • A.4.21 Special Device Drivers
    • A.4.22 Thread-Safety
    • A.4.23 Treatment of Error Conditions for Mathematical Functions
    • A.4.24 Treatment of NaN Arguments for Mathematical Functions
    • A.4.25 Utility
    • A.4.26 Variable Assignment
  • A.5 File Format Notation
  • A.6 Character Set
    • A.6.1 Portable Character Set
    • A.6.2 Character Encoding
    • A.6.3 C Language Wide-Character Codes
    • A.6.4 Character Set Description File
      • A.6.4.1 State-Dependent Character Encodings
  • A.7 Locale
    • A.7.1 General
    • A.7.2 POSIX Locale
    • A.7.3 Locale Definition
      • A.7.3.1 LC_CTYPE
      • A.7.3.2 LC_COLLATE
      • A.7.3.3 LC_MONETARY
      • A.7.3.4 LC_NUMERIC
      • A.7.3.5 LC_TIME
      • A.7.3.6 LC_MESSAGES
    • A.7.4 Locale Definition Grammar
      • A.7.4.1 Locale Lexical Conventions
      • A.7.4.2 Locale Grammar
    • A.7.5 Locale Definition Example
  • A.8 Environment Variables
    • A.8.1 Environment Variable Definition
    • A.8.2 Internationalization Variables
    • A.8.3 Other Environment Variables
      • COLUMNS, LINES
      • LOGNAME
      • PATH
      • SHELL
      • TZ
  • A.9 Regular Expressions
    • A.9.1 Regular Expression Definitions
    • A.9.2 Regular Expression General Requirements
    • A.9.3 Basic Regular Expressions
      • A.9.3.1 BREs Matching a Single Character or Collating Element
      • A.9.3.2 BRE Ordinary Characters
      • A.9.3.3 BRE Special Characters
      • A.9.3.4 Periods in BREs
      • A.9.3.5 RE Bracket Expression
      • A.9.3.6 BREs Matching Multiple Characters
      • A.9.3.7 BRE Precedence
      • A.9.3.8 BRE Expression Anchoring
    • A.9.4 Extended Regular Expressions
      • A.9.4.1 EREs Matching a Single Character or Collating Element
      • A.9.4.2 ERE Ordinary Characters
      • A.9.4.3 ERE Special Characters
      • A.9.4.4 Periods in EREs
      • A.9.4.5 ERE Bracket Expression
      • A.9.4.6 EREs Matching Multiple Characters
      • A.9.4.7 ERE Alternation
      • A.9.4.8 ERE Precedence
      • A.9.4.9 ERE Expression Anchoring
    • A.9.5 Regular Expression Grammar
      • A.9.5.1 BRE/ERE Grammar Lexical Conventions
      • A.9.5.2 RE and Bracket Expression Grammar
      • A.9.5.3 ERE Grammar
  • A.10 Directory Structure and Devices
    • A.10.1 Directory Structure and Files
    • A.10.2 Output Devices and Terminal Types
  • A.11 General Terminal Interface
    • A.11.1 Interface Characteristics
      • A.11.1.1 Opening a Terminal Device File
      • A.11.1.2 Process Groups
      • A.11.1.3 The Controlling Terminal
      • A.11.1.4 Terminal Access Control
      • A.11.1.5 Input Processing and Reading Data
      • A.11.1.6 Canonical Mode Input Processing
      • A.11.1.7 Non-Canonical Mode Input Processing
      • A.11.1.8 Writing Data and Output Processing
      • A.11.1.9 Special Characters
      • A.11.1.10 Modem Disconnect
      • A.11.1.11 Closing a Terminal Device File
    • A.11.2 Parameters that Can be Set
      • A.11.2.1 The termios Structure
      • A.11.2.2 Input Modes
      • A.11.2.3 Output Modes
      • A.11.2.4 Control Modes
      • A.11.2.5 Local Modes
      • A.11.2.6 Special Control Characters
  • A.12 Utility Conventions
    • A.12.1 Utility Argument Syntax
    • A.12.2 Utility Syntax Guidelines
  • A.13 Namespace and Future Directions
  • A.14 Headers
    • A.14.1 Format of Entries
    • A.14.2 Removed Headers in Issue 8
• B. Rationale for System Interfaces
  • B.1 Introduction
    • B.1.1 Change History
      • Changes from Issue 7 to Issue 8 (POSIX.1-2024)
      • New Features in Issue 8
      • Obsolescent Functions in Issue 8
      • Removed Functions in Issue 8
    • B.1.2 Relationship to Other Formal Standards
    • B.1.3 Format of Entries
  • B.2 General Information
    • B.2.1 Use and Implementation of Interfaces
      • B.2.1.1 Use and Implementation of Functions
      • B.2.1.2 Use and Implementation of Macros
    • B.2.2 The Compilation Environment
      • B.2.2.1 POSIX.1 Symbols
      • The _POSIX_C_SOURCE Feature Test Macro
      • The _XOPEN_SOURCE Feature Test Macro
      • The __STDC_WANT_LIB_EXT1__ Feature Test Macro
      • B.2.2.2 The Name Space
    • B.2.3 Error Numbers
      • Alternative Solutions for Per-Thread errno
      • Disallowing Return of the [EINTR] Error Code
      • B.2.3.1 Additional Error Numbers
    • B.2.4 Signal Concepts
      • Signal Names
      • B.2.4.1 Signal Generation and Delivery
      • B.2.4.2 Realtime Signal Generation and Delivery
      • B.2.4.3 Signal Actions
      • B.2.4.4 Signal Effects on Other Functions
    • B.2.5 Standard I/O Streams
      • B.2.5.1 Interaction of File Descriptors and Standard I/O Streams
      • B.2.5.2 Stream Orientation and Encoding Rules
    • B.2.6 File Descriptor Allocation
    • B.2.7 XSI Interprocess Communication
      • B.2.7.1 IPC General Description
    • B.2.8 Realtime
      • Advisory Information
      • Message Passing
      • Semaphores
      • B.2.8.1 Realtime Signals
      • Realtime Signals Extension
      • B.2.8.2 Asynchronous I/O
      • Overview
      • Models
      • Requirements
      • Standardization Issues
      • B.2.8.3 Memory Management
      • Memory Locking Functions
      • Mapped Files Functions
      • Shared Memory Functions
      • Typed Memory Functions
      • B.2.8.4 Process Scheduling
      • Sporadic Server Scheduling Policy
      • B.2.8.5 Clocks and Timers
      • Rationale for the Monotonic Clock
      • Execution Time Monitoring
      • Rationale Relating to Timeouts
    • B.2.9 Threads
      • Thread Creation Attributes
      • Thread Implementation Models
      • Thread-Specific Data
      • Barriers
      • Spin Locks
      • Robust Mutexes
      • Supported Threads Functions
      • Threads Extensions
      • B.2.9.1 Thread-Safety
      • B.2.9.2 Thread IDs
      • B.2.9.3 Thread Mutexes
      • B.2.9.4 Thread Scheduling
      • Scheduling Contention Scope
      • Scheduling Allocation Domain
      • Scheduling Documentation
      • Scheduling Contention Scope Attribute
      • Mixed Scopes
      • Dynamic Thread Scheduling Parameters Access
      • Mutex Initialization Scheduling Attributes
      • Change the Priority Ceiling of a Mutex
      • B.2.9.5 Thread Cancellation
      • Specifying the Operation to Cancel
      • A Special Signal Versus a Special Interface
      • Races Between Cancellation and Resuming Execution
      • Interaction of Cancellation with Asynchronous Signals
      • Thread Cancellation Overview
      • B.2.9.6 Thread Read-Write Locks
      • Background
      • Queuing of Waiting Threads
      • Comparison to fcntl() Locks
      • History of Resolution Issues
      • B.2.9.7 Thread Interactions with File Operations
      • B.2.9.8 Use of Application-Managed Thread Stacks
      • B.2.9.9 Synchronization Object Copies and Alternative Mappings
    • B.2.10 Sockets
      • B.2.10.1 Address Families
      • B.2.10.2 Addressing
      • B.2.10.3 Protocols
      • B.2.10.4 Routing
      • B.2.10.5 Interfaces
      • B.2.10.6 Socket Types
      • B.2.10.7 Socket I/O Mode
      • B.2.10.8 Socket Owner
      • B.2.10.9 Socket Queue Limits
      • B.2.10.10 Pending Error
      • B.2.10.11 Socket Receive Queue
      • B.2.10.12 Socket Out-of-Band Data State
      • B.2.10.13 Connection Indication Queue
      • B.2.10.14 Signals
      • B.2.10.15 Asynchronous Errors
      • B.2.10.16 Use of Options
      • B.2.10.17 Use of Sockets for Local UNIX Connections
      • B.2.10.18 Use of Sockets over Internet Protocols
      • B.2.10.19 Use of Sockets over Internet Protocols Based on IPv4
      • B.2.10.20 Use of Sockets over Internet Protocols Based on IPv6
    • B.2.11 Data Types
      • B.2.11.1 Defined Types
      • B.2.11.2 The char Type
    • B.2.12 Status Information
  • B.3 System Interfaces
    • B.3.1 System Interfaces Removed in this Version
      • B.3.1.1 STREAMS Option
      • B.3.1.2 Tracing Option
      • B.3.1.3 _longjmp() and _setjmp()
      • B.3.1.4 _tolower() and _toupper()
      • B.3.1.5 ftw()
      • B.3.1.6 getitimer() and setitimer()
      • B.3.1.7 gets()
      • B.3.1.8 gettimeofday()
      • B.3.1.9 isascii() and toascii()
      • B.3.1.10 pthread_getconcurrency() and pthread_setconcurrency()
      • B.3.1.11 rand_r()
      • B.3.1.12 setpgrp()
      • B.3.1.13 sighold(), sigpause(), and sigrelse()
      • B.3.1.14 sigignore(), siginterrupt(), and sigset()
      • B.3.1.15 tempnam()
      • B.3.1.16 ulimit()
      • B.3.1.17 utime()
    • B.3.2 System Interfaces Removed in the Previous Version
    • B.3.3 Examples for Spawn
      • Example Library Implementation of Spawn
      • I/O Redirection with Spawn
      • Spawning a Process Under a New User ID
    • Footnotes
• C. Rationale for Shell and Utilities
  • C.1 Introduction
    • C.1.1 Change History
      • Changes from Issue 7 to Issue 8 (POSIX.1-2024)
      • New Features in Issue 8
      • Removed Utilities in Issue 8
    • C.1.2 Relationship to Other Documents
      • C.1.2.1 System Interfaces
      • File Read, Write, and Creation
      • File Removal
      • C.1.2.2 Concepts Derived from the ISO C Standard
    • C.1.3 Utility Limits
    • C.1.4 Grammar Conventions
    • C.1.5 Utility Description Defaults
      • NAME
      • SYNOPSIS
      • DESCRIPTION
      • OPTIONS
      • OPERANDS
      • STDIN
      • INPUT FILES
      • ENVIRONMENT VARIABLES
      • ASYNCHRONOUS EVENTS
      • STDOUT
      • STDERR
      • OUTPUT FILES
      • EXTENDED DESCRIPTION
      • EXIT STATUS
      • CONSEQUENCES OF ERRORS
      • APPLICATION USAGE
      • EXAMPLES
      • RATIONALE
      • FUTURE DIRECTIONS
      • SEE ALSO
      • CHANGE HISTORY
    • C.1.6 Considerations for Utilities in Support of Files of Arbitrary Size
    • C.1.7 Built-In Utilities
    • C.1.8 Intrinsic Utilities
  • C.2 Shell Command Language
    • C.2.1 Shell Introduction
    • C.2.2 Quoting
      • C.2.2.1 Escape Character (Backslash)
      • C.2.2.2 Single-Quotes
      • C.2.2.3 Double-Quotes
      • C.2.2.4 Dollar-Single-Quotes
    • C.2.3 Token Recognition
      • C.2.3.1 Alias Substitution
    • C.2.4 Reserved Words
    • C.2.5 Parameters and Variables
      • C.2.5.1 Positional Parameters
      • C.2.5.2 Special Parameters
      • C.2.5.3 Shell Variables
    • C.2.6 Word Expansions
      • C.2.6.1 Tilde Expansion
      • C.2.6.2 Parameter Expansion
      • C.2.6.3 Command Substitution
      • C.2.6.4 Arithmetic Expansion
      • C.2.6.5 Field Splitting
      • C.2.6.6 Pathname Expansion
      • C.2.6.7 Quote Removal
    • C.2.7 Redirection
      • C.2.7.1 Redirecting Input
      • C.2.7.2 Redirecting Output
      • C.2.7.3 Appending Redirected Output
      • C.2.7.4 Here-Document
      • C.2.7.5 Duplicating an Input File Descriptor
      • C.2.7.6 Duplicating an Output File Descriptor
      • C.2.7.7 Open File Descriptors for Reading and Writing
    • C.2.8 Exit Status and Errors
      • C.2.8.1 Consequences of Shell Errors
      • C.2.8.2 Exit Status for Commands
    • C.2.9 Shell Commands
      • C.2.9.1 Simple Commands
      • Order of Processing
      • Variable Assignments
      • Commands with no Command Name
      • Command Search and Execution
      • Standard File Descriptors
      • Non-built-in Utility Execution
      • Examples
      • C.2.9.2 Pipelines
      • Exit Status
      • C.2.9.3 Lists
      • Asynchronous AND-OR Lists
      • Sequential AND-OR Lists
      • AND Lists
      • OR Lists
      • C.2.9.4 Compound Commands
      • Grouping Commands
      • For Loop
      • Case Conditional Construct
      • If Conditional Construct
      • While Loop
      • Until Loop
      • C.2.9.5 Function Definition Command
    • C.2.10 Shell Grammar
      • C.2.10.1 Shell Grammar Lexical Conventions
      • C.2.10.2 Shell Grammar Rules
    • C.2.11 Job Control
    • C.2.12 Signals and Error Handling
    • C.2.13 Shell Execution Environment
    • C.2.14 Pattern Matching Notation
      • C.2.14.1 Patterns Matching a Single Character
      • C.2.14.2 Patterns Matching Multiple Characters
      • Examples
      • C.2.14.3 Patterns Used for Filename Expansion
    • C.2.15 Special Built-In Utilities
  • C.3 Utilities
    • C.3.1 Utilities Removed in this Version
    • C.3.2 Utilities Removed in the Previous Version
    • C.3.3 Exclusion of Utilities
• D. Portability Considerations (Informative)
  • D.1 User Requirements
    • D.1.1 Configuration Interrogation
    • D.1.2 Process Management
    • D.1.3 Access to Data
    • D.1.4 Access to the Environment
    • D.1.5 Access to Determinism and Performance Enhancements
    • D.1.6 Operating System-Dependent Profile
    • D.1.7 I/O Interaction
    • D.1.8 Internationalization Interaction
    • D.1.9 C-Language Extensions
    • D.1.10 Command Language
    • D.1.11 Interactive Facilities
    • D.1.12 Accomplish Multiple Tasks Simultaneously
    • D.1.13 Complex Data Manipulation
    • D.1.14 File Hierarchy Manipulation
    • D.1.15 Locale Configuration
    • D.1.16 Inter-User Communication
    • D.1.17 System Environment
    • D.1.18 Printing
    • D.1.19 Software Development
  • D.2 Portability Capabilities
    • D.2.1 Configuration Interrogation
      • Unsatisfied Requirements
    • D.2.2 Process Management
    • D.2.3 Access to Data
    • D.2.4 Access to the Environment
      • Unsatisfied Requirements
    • D.2.5 Bounded (Realtime) Response
    • D.2.6 Operating System-Dependent Profile
      • Unsatisfied Requirements
    • D.2.7 I/O Interaction
      • Unsatisfied Requirements
    • D.2.8 Internationalization Interaction
      • Unsatisfied Requirements
    • D.2.9 C-Language Extensions
      • Unsatisfied Requirements
    • D.2.10 Command Language
      • Unsatisfied Requirements
    • D.2.11 Interactive Facilities
      • Unsatisfied Requirements
    • D.2.12 Accomplish Multiple Tasks Simultaneously
      • Unsatisfied Requirements
    • D.2.13 Complex Data Manipulation
      • Unsatisfied Requirements
    • D.2.14 File Hierarchy Manipulation
      • Unsatisfied Requirements
    • D.2.15 Locale Configuration
      • Unsatisfied Requirements
    • D.2.16 Inter-User Communication
      • Unsatisfied Requirements
    • D.2.17 System Environment
      • Unsatisfied Requirements
    • D.2.18 Printing
      • Unsatisfied Requirements
    • D.2.19 Software Development
      • Unsatisfied Requirements
    • D.2.20 Future Growth
  • D.3 Profiling Considerations
    • D.3.1 Configuration Options
    • D.3.2 Configuration Options (Shell and Utilities)
    • D.3.3 Configurable Limits
    • D.3.4 Configuration Options (System Interfaces)
    • D.3.5 Configurable Limits
    • D.3.6 Optional Behavior
    • Footnotes
• E. Subprofiling Considerations (Informative)
  • E.1 Subprofiling Option Groups
    • Footnotes

   

  return to top of page
  

  ---

  UNIX® is a registered Trademark of The Open Group.
  POSIX™ is a Trademark of The IEEE.
  Copyright © 2001-2024 The IEEE and The Open Group, All Rights Reserved
  [ Main Index | XBD | XSH | XCU | XRAT ]

  ---