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@menu
* Introduction:: Purpose of the GNU C Library.
* Error Reporting:: How library functions report errors.
* Memory Allocation:: Allocating memory dynamically and
manipulating it via pointers.
* Character Handling:: Character testing and conversion functions.
* String and Array Utilities:: Utilities for copying and comparing strings
and arrays.
* Extended Characters:: Support for extended character sets.
* Locales:: The country and language can affect the
behavior of library functions.
* Message Translation:: How to make the program speak the user's
language.
* Searching and Sorting:: General searching and sorting functions.
* Pattern Matching:: Matching shell ``globs'' and regular
expressions.
* I/O Overview:: Introduction to the I/O facilities.
* I/O on Streams:: Hign-level, portable I/O facilities.
* Low-Level I/O:: Low-level, less portable I/O.
* File System Interface:: Functions for manipulating files.
* Pipes and FIFOs:: A simple interprocess communication
mechanism.
* Sockets:: A more complicated IPC mechanism, with
networking support.
* Low-Level Terminal Interface:: How to change the characteristics of a
terminal device.
* Mathematics:: Math functions, useful constants, random
numbers.
* Arithmetic:: Low level arithmetic functions.
* Date and Time:: Functions for getting the date and time and
formatting them nicely.
* Non-Local Exits:: Jumping out of nested function calls.
* Signal Handling:: How to send, block, and handle signals.
* Process Startup:: Writing the beginning and end of your
program.
* Processes:: How to create processes and run other
programs.
* Job Control:: All about process groups and sessions.
* Name Service Switch:: Accessing system databases.
* Users and Groups:: How users are identified and classified.
* System Information:: Getting information about the hardware and
operating system.
* System Configuration:: Parameters describing operating system
limits.
Add-ons
* POSIX Threads:: The standard threads library.
Appendices
* Language Features:: C language features provided by the library.
* Library Summary:: A summary showing the syntax, header file,
and derivation of each library feature.
* Installation:: How to install the GNU C library.
* Maintenance:: How to enhance and port the GNU C Library.
* Contributors:: Who wrote what parts of the GNU C library.
* Copying:: The GNU Library General Public License says
how you can copy and share the GNU C Library.
Indices
* Concept Index:: Index of concepts and names.
* Type Index:: Index of types and type qualifiers.
* Function Index:: Index of functions and function-like macros.
* Variable Index:: Index of variables and variable-like macros.
* File Index:: Index of programs and files.
--- The Detailed Node Listing ---
Introduction
* Getting Started:: What this manual is for and how to use it.
* Standards and Portability:: Standards and sources upon which the GNU
C library is based.
* Using the Library:: Some practical uses for the library.
* Roadmap to the Manual:: Overview of the remaining chapters in
this manual.
Error Reporting
* Checking for Errors:: How errors are reported by library functions.
* Error Codes:: Error code macros; all of these expand
into integer constant values.
* Error Messages:: Mapping error codes onto error messages.
Memory Allocation
* Memory Concepts:: An introduction to concepts and terminology.
* Dynamic Allocation and C:: How to get different kinds of allocation in C.
* Unconstrained Allocation:: The @code{malloc} facility allows fully general
dynamic allocation.
* Allocation Debugging:: Finding memory leaks and not freed memory.
* Obstacks:: Obstacks are less general than malloc
but more efficient and convenient.
* Variable Size Automatic:: Allocation of variable-sized blocks
of automatic storage that are freed when the
calling function returns.
* Relocating Allocator:: Waste less memory, if you can tolerate
automatic relocation of the blocks you get.
Character Handling
* Classification of Characters:: Testing whether characters are
letters, digits, punctuation, etc.
* Case Conversion:: Case mapping, and the like.
String and Array Utilities
* Representation of Strings:: Introduction to basic concepts.
* String/Array Conventions:: Whether to use a string function or an
arbitrary array function.
* String Length:: Determining the length of a string.
* Copying and Concatenation:: Functions to copy the contents of strings
and arrays.
* String/Array Comparison:: Functions for byte-wise and character-wise
comparison.
* Collation Functions:: Functions for collating strings.
* Search Functions:: Searching for a specific element or substring.
* Finding Tokens in a String:: Splitting a string into tokens by looking
for delimiters.
* Encode Binary Data:: Encoding and Decoding of Binary Data.
* Argz and Envz Vectors:: Null-separated string vectors.
Extended Characters
* Extended Char Intro:: Multibyte codes versus wide characters.
* Locales and Extended Chars:: The locale selects the character codes.
* Multibyte Char Intro:: How multibyte codes are represented.
* Wide Char Intro:: How wide characters are represented.
* Wide String Conversion:: Converting wide strings to multibyte code
and vice versa.
* Length of Char:: how many bytes make up one multibyte char.
* Converting One Char:: Converting a string character by character.
* Example of Conversion:: Example showing why converting
one character at a time may be useful.
* Shift State:: Multibyte codes with "shift characters".
Locales
* Effects of Locale:: Actions affected by the choice of
locale.
* Choosing Locale:: How the user specifies a locale.
* Locale Categories:: Different purposes for which you can
select a locale.
* Setting the Locale:: How a program specifies the locale
with library functions.
* Standard Locales:: Locale names available on all systems.
* Numeric Formatting:: How to format numbers according to the
chosen locale.
Message Translation
* Message catalogs a la X/Open:: The @code{catgets} family of functions.
* The Uniforum approach:: The @code{gettext} family of functions.
Searching and Sorting
* Comparison Functions:: Defining how to compare two objects.
Since the sort and search facilities
are general, you have to specify the
ordering.
* Array Search Function:: The @code{bsearch} function.
* Array Sort Function:: The @code{qsort} function.
* Search/Sort Example:: An example program.
* Hash Search Function:: The @code{hsearch} function.
* Tree Search Function:: The @code{tsearch} function.
Pattern Matching
* Wildcard Matching:: Matching a wildcard pattern against a single string.
* Globbing:: Finding the files that match a wildcard pattern.
* Regular Expressions:: Matching regular expressions against strings.
* Word Expansion:: Expanding shell variables, nested commands,
arithmetic, and wildcards.
This is what the shell does with shell commands.
I/O Overview
* I/O Concepts:: Some basic information and terminology.
* File Names:: How to refer to a file.
I/O on Streams
* Streams:: About the data type representing a stream.
* Standard Streams:: Streams to the standard input and output
devices are created for you.
* Opening Streams:: How to create a stream to talk to a file.
* Closing Streams:: Close a stream when you are finished with it.
* Simple Output:: Unformatted output by characters and lines.
* Character Input:: Unformatted input by characters and words.
* Line Input:: Reading a line or a record from a stream.
* Unreading:: Peeking ahead/pushing back input just read.
* Block Input/Output:: Input and output operations on blocks of data.
* Formatted Output:: @code{printf} and related functions.
* Customizing Printf:: You can define new conversion specifiers for
@code{printf} and friends.
* Formatted Input:: @code{scanf} and related functions.
* EOF and Errors:: How you can tell if an I/O error happens.
* Binary Streams:: Some systems distinguish between text files
and binary files.
* File Positioning:: About random-access streams.
* Portable Positioning:: Random access on peculiar ISO C systems.
* Stream Buffering:: How to control buffering of streams.
* Other Kinds of Streams:: Streams that do not necessarily correspond
to an open file.
* Formatted Messages:: Print strictly formatted messages.
Low-Level I/O
* Opening and Closing Files:: How to open and close file
descriptors.
* Truncating Files:: Change the size of a file.
* I/O Primitives:: Reading and writing data.
* File Position Primitive:: Setting a descriptor's file
position.
* Descriptors and Streams:: Converting descriptor to stream
or vice-versa.
* Stream/Descriptor Precautions:: Precautions needed if you use both
descriptors and streams.
* Waiting for I/O:: How to check for input or output
on multiple file descriptors.
* Synchronizing I/O:: Making sure all I/O actions completed.
* Asynchronous I/O:: Perform I/O in parallel.
* Control Operations:: Various other operations on file
descriptors.
* Duplicating Descriptors:: Fcntl commands for duplicating
file descriptors.
* Descriptor Flags:: Fcntl commands for manipulating
flags associated with file
descriptors.
* File Status Flags:: Fcntl commands for manipulating
flags associated with open files.
* File Locks:: Fcntl commands for implementing
file locking.
* Interrupt Input:: Getting an asynchronous signal when
input arrives.
File System Interface
* Working Directory:: This is used to resolve relative
file names.
* Accessing Directories:: Finding out what files a directory
contains.
* Working on Directory Trees:: Apply actions to all files or a selectable
subset of a directory hierarchy.
* Hard Links:: Adding alternate names to a file.
* Symbolic Links:: A file that ``points to'' a file name.
* Deleting Files:: How to delete a file, and what that means.
* Renaming Files:: Changing a file's name.
* Creating Directories:: A system call just for creating a directory.
* File Attributes:: Attributes of individual files.
* Making Special Files:: How to create special files.
* Temporary Files:: Naming and creating temporary files.
Pipes and FIFOs
* Creating a Pipe:: Making a pipe with the @code{pipe} function.
* Pipe to a Subprocess:: Using a pipe to communicate with a
child process.
* FIFO Special Files:: Making a FIFO special file.
* Pipe Atomicity:: When pipe (or FIFO) I/O is atomic.
Sockets
* Socket Concepts:: Basic concepts you need to know about.
* Communication Styles::Stream communication, datagrams, and other styles.
* Socket Addresses:: How socket names (``addresses'') work.
* Interface Naming:: Identifying specific network interfaces.
* Local Namespace:: Details about the local namespace.
* Internet Namespace:: Details about the Internet namespace.
* Misc Namespaces:: Other namespaces not documented fully here.
* Open/Close Sockets:: Creating sockets and destroying them.
* Connections:: Operations on sockets with connection state.
* Datagrams:: Operations on datagram sockets.
* Inetd:: Inetd is a daemon that starts servers on request.
The most convenient way to write a server
is to make it work with Inetd.
* Socket Options:: Miscellaneous low-level socket options.
* Networks Database:: Accessing the database of network names.
Low-Level Terminal Interface
* Is It a Terminal:: How to determine if a file is a terminal
device, and what its name is.
* I/O Queues:: About flow control and typeahead.
* Canonical or Not:: Two basic styles of input processing.
* Terminal Modes:: How to examine and modify flags controlling
details of terminal I/O: echoing,
signals, editing.
* Line Control:: Sending break sequences, clearing
terminal buffers @dots{}
* Noncanon Example:: How to read single characters without echo.
* Pseudo-Terminals:: How to open a pseudo-terminal.
Mathematics
* Mathematical Constants:: Precise numeric values for often-used
constants.
* Trig Functions:: Sine, cosine, tangent, and friends.
* Inverse Trig Functions:: Arcsine, arccosine, etc.
* Exponents and Logarithms:: Also pow and sqrt.
* Hyperbolic Functions:: sinh, cosh, tanh, etc.
* Special Functions:: Bessel, gamma, erf.
* Pseudo-Random Numbers:: Functions for generating pseudo-random
numbers.
* FP Function Optimizations:: Fast code or small code.
Arithmetic
* Floating Point Numbers:: Basic concepts. IEEE 754.
* Floating Point Classes:: The five kinds of floating-point number.
* Floating Point Errors:: When something goes wrong in a calculation.
* Rounding:: Controlling how results are rounded.
* Control Functions:: Saving and restoring the FPU's state.
* Arithmetic Functions:: Fundamental operations provided by the library.
* Complex Numbers:: The types. Writing complex constants.
* Operations on Complex:: Projection, conjugation, decomposition.
* Integer Division:: Integer division with guaranteed rounding.
* Parsing of Numbers:: Converting strings to numbers.
* System V Number Conversion:: An archaic way to convert numbers to strings.
Date and Time
* Processor Time:: Measures processor time used by a program.
* Calendar Time:: Manipulation of ``real'' dates and times.
* Setting an Alarm:: Sending a signal after a specified time.
* Sleeping:: Waiting for a period of time.
* Resource Usage:: Measuring various resources used.
* Limits on Resources:: Specifying limits on resource usage.
* Priority:: Reading or setting process run priority.
Non-Local Exits
* Intro: Non-Local Intro. When and how to use these facilities.
* Details: Non-Local Details. Functions for nonlocal exits.
* Non-Local Exits and Signals:: Portability issues.
Signal Handling
* Concepts of Signals:: Introduction to the signal facilities.
* Standard Signals:: Particular kinds of signals with
standard names and meanings.
* Signal Actions:: Specifying what happens when a
particular signal is delivered.
* Defining Handlers:: How to write a signal handler function.
* Interrupted Primitives:: Signal handlers affect use of @code{open},
@code{read}, @code{write} and other functions.
* Generating Signals:: How to send a signal to a process.
* Blocking Signals:: Making the system hold signals temporarily.
* Waiting for a Signal:: Suspending your program until a signal
arrives.
* Signal Stack:: Using a Separate Signal Stack.
* BSD Signal Handling:: Additional functions for backward
compatibility with BSD.
Process Startup
* Program Arguments:: Parsing your program's command-line arguments.
* Environment Variables:: How to access parameters inherited from
a parent process.
* Program Termination:: How to cause a process to terminate and
return status information to its parent.
Processes
* Running a Command:: The easy way to run another program.
* Process Creation Concepts:: An overview of the hard way to do it.
* Process Identification:: How to get the process ID of a process.
* Creating a Process:: How to fork a child process.
* Executing a File:: How to make a process execute another program.
* Process Completion:: How to tell when a child process has completed.
* Process Completion Status:: How to interpret the status value
returned from a child process.
* BSD Wait Functions:: More functions, for backward compatibility.
* Process Creation Example:: A complete example program.
Job Control
* Concepts of Job Control:: Jobs can be controlled by a shell.
* Job Control is Optional:: Not all POSIX systems support job control.
* Controlling Terminal:: How a process gets its controlling terminal.
* Access to the Terminal:: How processes share the controlling terminal.
* Orphaned Process Groups:: Jobs left after the user logs out.
* Implementing a Shell:: What a shell must do to implement job control.
* Functions for Job Control:: Functions to control process groups.
Name Service Switch
* NSS Basics:: What is this NSS good for.
* NSS Configuration File:: Configuring NSS.
* NSS Module Internals:: How does it work internally.
* Extending NSS:: What to do to add services or databases.
Users and Groups
* User and Group IDs:: Each user has a unique numeric ID;
likewise for groups.
* Process Persona:: The user IDs and group IDs of a process.
* Why Change Persona:: Why a program might need to change
its user and/or group IDs.
* How Change Persona:: Changing the user and group IDs.
* Reading Persona:: How to examine the user and group IDs.
* Setting User ID:: Functions for setting the user ID.
* Setting Groups:: Functions for setting the group IDs.
* Enable/Disable Setuid:: Turning setuid access on and off.
* Setuid Program Example:: The pertinent parts of one sample program.
* Tips for Setuid:: How to avoid granting unlimited access.
* Who Logged In:: Getting the name of the user who logged in,
or of the real user ID of the current process.
* User Accounting Database:: Keeping information about users and various
actions in databases.
* User Database:: Functions and data structures for
accessing the user database.
* Group Database:: Functions and data structures for
accessing the group database.
* Database Example:: Example program showing the use of database
inquiry functions.
* Netgroup Database:: Functions for accessing the netgroup database.
System Information
* Host Identification:: Determining the name of the machine.
* Hardware/Software Type ID:: Determining the hardware type of the
machine and what operating system it is
running.
* Filesystem handling:: Which is mounted and/or available?
System Configuration
* General Limits:: Constants and functions that describe
various process-related limits that have
one uniform value for any given machine.
* System Options:: Optional POSIX features.
* Version Supported:: Version numbers of POSIX.1 and POSIX.2.
* Sysconf:: Getting specific configuration values
of general limits and system options.
* Minimums:: Minimum values for general limits.
* Limits for Files:: Size limitations that pertain to individual files.
These can vary between file systems
or even from file to file.
* Options for Files:: Optional features that some files may support.
* File Minimums:: Minimum values for file limits.
* Pathconf:: Getting the limit values for a particular file.
* Utility Limits:: Capacity limits of some POSIX.2 utility programs.
* Utility Minimums:: Minimum allowable values of those limits.
* String Parameters:: Getting the default search path.
POSIX Threads
* Basic Thread Operations:: Creating, terminating, and waiting for threads.
* Thread Attributes:: Tuning thread scheduling.
* Cancellation:: Stopping a thread before it's done.
* Cleanup Handlers:: Deallocating resources when a thread is
cancelled.
* Mutexes:: One way to synchronize threads.
* Condition Variables:: Another way.
* POSIX Semaphores:: And a third way.
* Thread-Specific Data:: Variables with different values in
different threads.
* Threads and Signal Handling:: Why you should avoid mixing the two, and
how to do it if you must.
* Miscellaneous Thread Functions:: A grab bag of utility routines.
Language Features
* Consistency Checking:: Using @code{assert} to abort if
something ``impossible'' happens.
* Variadic Functions:: Defining functions with varying numbers
of args.
* Null Pointer Constant:: The macro @code{NULL}.
* Important Data Types:: Data types for object sizes.
* Data Type Measurements:: Parameters of data type representations.
Installation
* Tools for Installation:: We recommend using these tools to build.
* Supported Configurations:: What systems the GNU C library runs on.
* Tips for Installation:: Useful hints for the installation.
* Reporting Bugs:: How to report bugs (if you want to
get them fixed) and other troubles
you may have with the GNU C library.
Maintenance
* Source Layout:: How to add new functions or header files
to the GNU C library.
* Porting:: How to port the GNU C library to
a new machine or operating system.
@end menu
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