Introduction Getting Started Standards and Portability ISO C POSIX (The Portable Operating System Interface) Berkeley Unix SVID (The System V Interface Description) XPG (The X/Open Portability Guide) Using the Library Header Files Macro Definitions of Functions Reserved Names Feature Test Macros Roadmap to the Manual Error Reporting Checking for Errors Error Codes Error Messages Memory Allocation Dynamic Memory Allocation Concepts Dynamic Allocation and C Unconstrained Allocation Basic Storage Allocation Examples of malloc Freeing Memory Allocated with malloc Changing the Size of a Block Allocating Cleared Space Efficiency Considerations for malloc Allocating Aligned Memory Blocks Malloc Tunable Parameters Heap Consistency Checking Storage Allocation Hooks Statistics for Storage Allocation with malloc Summary of malloc-Related Functions Allocation Debugging How to install the tracing functionality Example programs excerpts Some more or less clever ideas Interpreting the traces Obstacks Creating Obstacks Preparing for Using Obstacks Allocation in an Obstack Freeing Objects in an Obstack Obstack Functions and Macros Growing Objects Extra Fast Growing Objects Status of an Obstack Alignment of Data in Obstacks Obstack Chunks Summary of Obstack Functions Automatic Storage with Variable Size alloca Example Advantages of alloca Disadvantages of alloca GNU C Variable-Size Arrays Character Handling Classification of Characters Case Conversion Character class determination for wide characters Notes on using the wide character classes Mapping of wide characters. String and Array Utilities Representation of Strings String and Array Conventions String Length Copying and Concatenation String/Array Comparison Collation Functions Search Functions Finding Tokens in a String Encode Binary Data Argz and Envz Vectors Argz Functions Envz Functions Character Set Handling Introduction to Extended Characters Overview about Character Handling Functions Restartable Multibyte Conversion Functions Selecting the conversion and its properties Representing the state of the conversion Converting Single Characters Converting Multibyte and Wide Character Strings A Complete Multibyte Conversion Example Non-reentrant Conversion Function Non-reentrant Conversion of Single Characters Non-reentrant Conversion of Strings States in Non-reentrant Functions Generic Charset Conversion Generic Character Set Conversion Interface A complete iconv example Some Details about other iconv Implementations The iconv Implementation in the GNU C library Format of `gconv-modules' files Finding the conversion path in iconv iconv module data structures iconv module interfaces Locales and Internationalization What Effects a Locale Has Choosing a Locale Categories of Activities that Locales Affect How Programs Set the Locale Standard Locales Accessing the Locale Information localeconv: It is portable but ... Generic Numeric Formatting Parameters Printing the Currency Symbol Printing the Sign of an Amount of Money Pinpoint Access to Locale Data A dedicated function to format numbers Message Translation X/Open Message Catalog Handling The catgets function family Format of the message catalog files Generate Message Catalogs files How to use the catgets interface Not using symbolic names Using symbolic names How does to this allow to develop The Uniforum approach to Message Translation The gettext family of functions What has to be done to translate a message? How to determine which catalog to be used User influence on gettext Programs to handle message catalogs for gettext Searching and Sorting Defining the Comparison Function Array Search Function Array Sort Function Searching and Sorting Example The hsearch function. The tsearch function. Pattern Matching Wildcard Matching Globbing Calling glob Flags for Globbing More Flags for Globbing Regular Expression Matching POSIX Regular Expression Compilation Flags for POSIX Regular Expressions Matching a Compiled POSIX Regular Expression Match Results with Subexpressions Complications in Subexpression Matching POSIX Regexp Matching Cleanup Shell-Style Word Expansion The Stages of Word Expansion Calling wordexp Flags for Word Expansion wordexp Example Details of Tilde Expansion Details of Variable Substitution Input/Output Overview Input/Output Concepts Streams and File Descriptors File Position File Names Directories File Name Resolution File Name Errors Portability of File Names Input/Output on Streams Streams Standard Streams Opening Streams Closing Streams Simple Output by Characters or Lines Character Input Line-Oriented Input Unreading What Unreading Means Using ungetc To Do Unreading Block Input/Output Formatted Output Formatted Output Basics Output Conversion Syntax Table of Output Conversions Integer Conversions Floating-Point Conversions Other Output Conversions Formatted Output Functions Dynamically Allocating Formatted Output Variable Arguments Output Functions Parsing a Template String Example of Parsing a Template String Customizing printf Registering New Conversions Conversion Specifier Options Defining the Output Handler printf Extension Example Predefined printf Handlers Formatted Input Formatted Input Basics Input Conversion Syntax Table of Input Conversions Numeric Input Conversions String Input Conversions Dynamically Allocating String Conversions Other Input Conversions Formatted Input Functions Variable Arguments Input Functions End-Of-File and Errors Text and Binary Streams File Positioning Portable File-Position Functions Stream Buffering Buffering Concepts Flushing Buffers Controlling Which Kind of Buffering Other Kinds of Streams String Streams Obstack Streams Programming Your Own Custom Streams Custom Streams and Cookies Custom Stream Hook Functions Formatted Messages Printing Formatted Messages Adding Severity Classes How to use fmtmsg and addseverity Low-Level Input/Output Opening and Closing Files Change the size of a file Input and Output Primitives Setting the File Position of a Descriptor Descriptors and Streams Dangers of Mixing Streams and Descriptors Linked Channels Independent Channels Cleaning Streams Fast Scatter-Gather I/O Memory-mapped I/O Waiting for Input or Output Synchronizing I/O operations Perform I/O Operations in Parallel Asynchronous Read and Write Operations Getting the Status of AIO Operations Getting into a Consistent State Cancelation of AIO Operations How to optimize the AIO implementation Control Operations on Files Duplicating Descriptors File Descriptor Flags File Status Flags File Access Modes Open-time Flags I/O Operating Modes Getting and Setting File Status Flags File Locks Interrupt-Driven Input Generic I/O Control operations File System Interface Working Directory Accessing Directories Format of a Directory Entry Opening a Directory Stream Reading and Closing a Directory Stream Simple Program to List a Directory Random Access in a Directory Stream Scanning the Content of a Directory Simple Program to List a Directory, Mark II Working on Directory Trees Hard Links Symbolic Links Deleting Files Renaming Files Creating Directories File Attributes What the File Attribute Values Mean Reading the Attributes of a File Testing the Type of a File File Owner The Mode Bits for Access Permission How Your Access to a File is Decided Assigning File Permissions Testing Permission to Access a File File Times File Size Making Special Files Temporary Files Pipes and FIFOs Creating a Pipe Pipe to a Subprocess FIFO Special Files Atomicity of Pipe I/O Sockets Socket Concepts Communication Styles Socket Addresses Address Formats Setting the Address of a Socket Reading the Address of a Socket Interface Naming The Local Namespace Local Namespace Concepts Details of Local Namespace Example of Local-Namespace Sockets The Internet Namespace Internet Socket Address Formats Host Addresses Internet Host Addresses Host Address Data Type Host Address Functions Host Names Internet Ports The Services Database Byte Order Conversion Protocols Database Internet Socket Example Other Namespaces Opening and Closing Sockets Creating a Socket Closing a Socket Socket Pairs Using Sockets with Connections Making a Connection Listening for Connections Accepting Connections Who is Connected to Me? Transferring Data Sending Data Receiving Data Socket Data Options Byte Stream Socket Example Byte Stream Connection Server Example Out-of-Band Data Datagram Socket Operations Sending Datagrams Receiving Datagrams Datagram Socket Example Example of Reading Datagrams The inetd Daemon inetd Servers Configuring inetd Socket Options Socket Option Functions Socket-Level Options Networks Database Low-Level Terminal Interface Identifying Terminals I/O Queues Two Styles of Input: Canonical or Not Terminal Modes Terminal Mode Data Types Terminal Mode Functions Setting Terminal Modes Properly Input Modes Output Modes Control Modes Local Modes Line Speed Special Characters Characters for Input Editing Characters that Cause Signals Special Characters for Flow Control Other Special Characters Noncanonical Input Line Control Functions Noncanonical Mode Example Pseudo-Terminals Allocating Pseudo-Terminals Opening a Pseudo-Terminal Pair Mathematics Predefined Mathematical Constants Trigonometric Functions Inverse Trigonometric Functions Exponentiation and Logarithms Hyperbolic Functions Special Functions Pseudo-Random Numbers ISO C Random Number Functions BSD Random Number Functions SVID Random Number Function Is Fast Code or Small Code preferred? Arithmetic Functions Floating Point Numbers Floating-Point Number Classification Functions Errors in Floating-Point Calculations FP Exceptions Infinity and NaN Examining the FPU status word Error Reporting by Mathematical Functions Rounding Modes Floating-Point Control Functions Arithmetic Functions Absolute Value Normalization Functions Rounding Functions Remainder Functions Setting and modifying single bits of FP values Floating-Point Comparison Functions Miscellaneous FP arithmetic functions Complex Numbers Projections, Conjugates, and Decomposing of Complex Numbers Integer Division Parsing of Numbers Parsing of Integers Parsing of Floats Old-fashioned System V number-to-string functions Date and Time Processor Time Basic CPU Time Inquiry Detailed Elapsed CPU Time Inquiry Calendar Time Simple Calendar Time High-Resolution Calendar Broken-down Time Formatting Date and Time Convert textual time and date information back Interpret string according to given format A user-friendlier way to parse times and dates Specifying the Time Zone with TZ Functions and Variables for Time Zones Time Functions Example Precision Time Setting an Alarm Sleeping Resource Usage Limiting Resource Usage Process Priority Non-Local Exits Introduction to Non-Local Exits Details of Non-Local Exits Non-Local Exits and Signals Signal Handling Basic Concepts of Signals Some Kinds of Signals Concepts of Signal Generation How Signals Are Delivered Standard Signals Program Error Signals Termination Signals Alarm Signals Asynchronous I/O Signals Job Control Signals Operation Error Signals Miscellaneous Signals Signal Messages Specifying Signal Actions Basic Signal Handling Advanced Signal Handling Interaction of signal and sigaction sigaction Function Example Flags for sigaction Initial Signal Actions Defining Signal Handlers Signal Handlers that Return Handlers That Terminate the Process Nonlocal Control Transfer in Handlers Signals Arriving While a Handler Runs Signals Close Together Merge into One Signal Handling and Nonreentrant Functions Atomic Data Access and Signal Handling Problems with Non-Atomic Access Atomic Types Atomic Usage Patterns Primitives Interrupted by Signals Generating Signals Signaling Yourself Signaling Another Process Permission for using kill Using kill for Communication Blocking Signals Why Blocking Signals is Useful Signal Sets Process Signal Mask Blocking to Test for Delivery of a Signal Blocking Signals for a Handler Checking for Pending Signals Remembering a Signal to Act On Later Waiting for a Signal Using pause Problems with pause Using sigsuspend Using a Separate Signal Stack BSD Signal Handling BSD Function to Establish a Handler BSD Functions for Blocking Signals Process Startup and Termination Program Arguments Program Argument Syntax Conventions Parsing Program Arguments Parsing program options using getopt Using the getopt function Example of Parsing Arguments with getopt Parsing Long Options with getopt_long Example of Parsing Long Options with getopt_long Parsing Program Options with Argp The argp_parse Function Argp Global Variables Specifying Argp Parsers Specifying Options in an Argp Parser Flags for Argp Options Argp Parser Functions Special Keys for Argp Parser Functions Functions For Use in Argp Parsers Argp Parsing State Combining Multiple Argp Parsers Flags for argp_parse Customizing Argp Help Output Special Keys for Argp Help Filter Functions The argp_help Function Flags for the argp_help Function Argp Examples A Minimal Program Using Argp A Program Using Argp with Only Default Options A Program Using Argp with User Options A Program Using Multiple Combined Argp Parsers Argp User Customization Parsing of Suboptions Parsing of Suboptions Example Environment Variables Environment Access Standard Environment Variables Program Termination Normal Termination Exit Status Cleanups on Exit Aborting a Program Termination Internals Processes Running a Command Process Creation Concepts Process Identification Creating a Process Executing a File Process Completion Process Completion Status BSD Process Wait Functions Process Creation Example Job Control Concepts of Job Control Job Control is Optional Controlling Terminal of a Process Access to the Controlling Terminal Orphaned Process Groups Implementing a Job Control Shell Data Structures for the Shell Initializing the Shell Launching Jobs Foreground and Background Stopped and Terminated Jobs Continuing Stopped Jobs The Missing Pieces Functions for Job Control Identifying the Controlling Terminal Process Group Functions Functions for Controlling Terminal Access System Databases and Name Service Switch NSS Basics The NSS Configuration File Services in the NSS configuration File Actions in the NSS configuration Notes on the NSS Configuration File NSS Module Internals The Naming Scheme of the NSS Modules The Interface of the Function in NSS Modules Extending NSS Adding another Service to NSS Internals of the NSS Module Functions Users and Groups User and Group IDs The Persona of a Process Why Change the Persona of a Process? How an Application Can Change Persona Reading the Persona of a Process Setting the User ID Setting the Group IDs Enabling and Disabling Setuid Access Setuid Program Example Tips for Writing Setuid Programs Identifying Who Logged In The User Accounting Database Manipulating the User Accounting Database XPG User Accounting Database Functions Logging In and Out User Database The Data Structure that Describes a User Looking Up One User Scanning the List of All Users Writing a User Entry Group Database The Data Structure for a Group Looking Up One Group Scanning the List of All Groups User and Group Database Example Netgroup Database Netgroup Data Looking up one Netgroup Testing for Netgroup Membership System Information Host Identification Hardware/Software Type Identification Which filesystems are mounted and/or available? System Configuration Parameters General Capacity Limits Overall System Options Which Version of POSIX is Supported Using sysconf Definition of sysconf Constants for sysconf Parameters Examples of sysconf Minimum Values for General Capacity Limits Limits on File System Capacity Optional Features in File Support Minimum Values for File System Limits Using pathconf Utility Program Capacity Limits Minimum Values for Utility Limits String-Valued Parameters DES Encryption and Password Handling Legal Problems Reading Passwords Encrypting Passwords DES Encryption POSIX Threads Basic Thread Operations Thread Attributes Cancellation Cleanup Handlers Mutexes Condition Variables POSIX Semaphores Thread-Specific Data Threads and Signal Handling Miscellaneous Thread Functions C Language Facilities in the Library Explicitly Checking Internal Consistency Variadic Functions Why Variadic Functions are Used How Variadic Functions are Defined and Used Syntax for Variable Arguments Receiving the Argument Values How Many Arguments Were Supplied Calling Variadic Functions Argument Access Macros Example of a Variadic Function Old-Style Variadic Functions Null Pointer Constant Important Data Types Data Type Measurements Computing the Width of an Integer Data Type Range of an Integer Type Floating Type Macros Floating Point Representation Concepts Floating Point Parameters IEEE Floating Point Structure Field Offset Measurement Summary of Library Facilities Installing the GNU C Library Configuring and compiling GNU Libc Installing the C Library Recommended Tools for Compilation Supported Configurations Specific advice for Linux systems Reporting Bugs Library Maintenance Adding New Functions Porting the GNU C Library Layout of the `sysdeps' Directory Hierarchy Porting the GNU C Library to Unix Systems Contributors to the GNU C Library GNU LIBRARY GENERAL PUBLIC LICENSE Preamble TERMS AND CONDITIONS FOR COPYING,
DISTRIBUTION AND MODIFICATION How to Apply These Terms to Your New Libraries Concept Index Type Index Function and Macro Index Variable and Constant Macro Index Program and File Index

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