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.\"     @(#)intro.3	8.1 (Berkeley) 6/5/93
.\" $FreeBSD$
.\"
.Dd March 22, 2017
.Dt INTRO 3
.Os
.Sh NAME
.Nm intro
.Nd introduction to the C libraries
.Sh DESCRIPTION
This section provides an overview of the C
library functions, their error returns and other
common definitions and concepts.
Most of these functions are available from the C library,
.Em libc .
Other libraries, such as the math library,
.Em libm ,
must be indicated at compile time with the
.Fl l
option of the compiler.
.Pp
The various libraries (followed by the loader flag):
.Bl -tag -width "libc (-lc)"
.It Em libc Pq Fl l Ns Ar c
Standard C library functions.
When using the C compiler
.Xr cc 1 ,
it is not necessary
to supply the loader flag
.Fl l Ns Ar c
for these functions.
There are several `libraries' or groups of functions included inside of
.Em libc
: the standard
.Tn I/O
routines,
database routines,
bit operators,
string operators,
character tests and character operators,
des encryption routines,
storage allocation, time functions, signal handling and more.
.It Em libcurses Pq Fl l Ns Ar curses Fl l Ns Ar termcap
Terminal independent screen management routines
for two dimensional non-bitmap display terminals.
(See
.Xr ncurses 3 . )
.It Em libcompat Pq Fl l Ns Ar compat
Functions which are obsolete but are available for compatibility with
.Bx 4.3 .
In particular,
a number of system call interfaces provided in previous releases of
.Bx
have been included for source code compatibility.
Use of these routines should, for the most part, be avoided.
The manual page entry for each compatibility routine
indicates the proper interface to use.
.It Em libkvm Pq Fl l Ns Ar kvm
Functions used to access kernel memory are in this library.
They can be used
against both a running system and a crash dump.
(See
.Xr kvm 3 . )
.It Em libl Pq Fl l Ns Ar l
The library for
.Xr lex 1 .
.It Em libm Pq Fl l Ns Ar m
The math library,
.Em libm .
The math library is loaded as needed by the Pascal compiler,
but not by the C compiler which requires the
.Fl l Ns Ar m
flag.
(See
.Xr math 3 . )
.It Em libmp Pq Fl l Ns Ar mp
.It Em libtermcap Pq Fl l Ns Ar termcap
The terminal independent operation library package.
(See
.Xr termcap 3 . )
.It Em liby Pq Fl l Ns Ar y
The library for
.Xr yacc 1 .
.El
.Sh FILES
.Bl -tag -width /usr/lib/libm_p.a -compact
.It Pa /usr/lib/libc.a
the C library
.It Pa /usr/lib/libc_p.a
the C library compiled for profiling
.It Pa /usr/lib/libm.a
the math library
.It Pa /usr/lib/libm_p.a
the math library compiled for profiling
.El
.Sh SEE ALSO
.Xr cc 1 ,
.Xr ld 1 ,
.Xr nm 1 ,
.Xr intro 2 ,
.Xr math 3 ,
.Xr stdio 3
.Sh HISTORY
An
.Nm
manual appeared in
.At v7 .