.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)

.\"

.\" %%%LICENSE_START(VERBATIM)

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.\" Since the Linux kernel and libraries are constantly changing, this

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.\" References consulted:

.\"     Linux libc source code

.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)

.\"     386BSD man pages

.\" Modified Sat Jul 24 19:19:11 1993 by Rik Faith (faith@cs.unc.edu)

.\" Modified Wed Oct 18 20:23:54 1995 by Martin Schulze <joey@infodrom.north.de>

.\" Modified Mon Apr 22 01:50:54 1996 by Martin Schulze <joey@infodrom.north.de>

.\" 2001-07-25 added a clause about NULL proto (Martin Michlmayr or David N. Welton)

.\"

.TH GETSERVENT 3  2017-09-15 "GNU" "Linux Programmer's Manual"

.SH NAME

getservent, getservbyname, getservbyport, setservent, endservent \-

get service entry

.SH SYNOPSIS

.nf

.B #include <netdb.h>

.PP

.B struct servent *getservent(void);

.PP

.BI "struct servent *getservbyname(const char *" name ", const char *" proto );

.PP

.BI "struct servent *getservbyport(int " port ", const char *" proto );

.PP

.BI "void setservent(int " stayopen );

.PP

.B void endservent(void);

.fi

.SH DESCRIPTION

The

.BR getservent ()

function reads the next entry from the services database (see

.BR services (5))

and returns a

.I servent

structure containing

the broken-out fields from the entry.

A connection is opened to the database if necessary.

.PP

The

.BR getservbyname ()

function returns a

.I servent

structure

for the entry from the database

that matches the service

.I name

using protocol

.IR proto .

If

.I proto

is NULL, any protocol will be matched.

A connection is opened to the database if necessary.

.PP

The

.BR getservbyport ()

function returns a

.I servent

structure

for the entry from the database

that matches the port

.I port

(given in network byte order)

using protocol

.IR proto .

If

.I proto

is NULL, any protocol will be matched.

A connection is opened to the database if necessary.

.PP

The

.BR setservent ()

function opens a connection to the database,

and sets the next entry to the first entry.

If

.I stayopen

is nonzero,

then the connection to the database

will not be closed between calls to one of the

.BR getserv* ()

functions.

.PP

The

.BR endservent ()

function closes the connection to the database.

.PP

The

.I servent

structure is defined in

.I <netdb.h>

as follows:

.PP

.in +4n

.EX

struct servent {

    char  *s_name;       /* official service name */

    char **s_aliases;    /* alias list */

    int    s_port;       /* port number */

    char  *s_proto;      /* protocol to use */

}

.EE

.in

.PP

The members of the

.I servent

structure are:

.TP

.I s_name

The official name of the service.

.TP

.I s_aliases

A NULL-terminated list of alternative names for the service.

.TP

.I s_port

The port number for the service given in network byte order.

.TP

.I s_proto

The name of the protocol to use with this service.

.SH RETURN VALUE

The

.BR getservent (),

.BR getservbyname ()

and

.BR getservbyport ()

functions return a pointer to a

statically allocated

.I servent

structure, or NULL if an

error occurs or the end of the file is reached.

.SH FILES

.TP

.I /etc/services

services database file

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lbw15 lb lbw25

l l l.

Interface	Attribute	Value

T{

.BR getservent ()

T}	Thread safety	T{

MT-Unsafe race:servent

.br

race:serventbuf locale

T}

T{

.BR getservbyname ()

T}	Thread safety	T{

MT-Unsafe race:servbyname

.br

locale

T}

T{

.BR getservbyport ()

T}	Thread safety	T{

MT-Unsafe race:servbyport

.br

locale

T}

T{

.BR setservent (),

.br

.BR endservent ()

T}	Thread safety	T{

MT-Unsafe race:servent

.br

locale

T}

.TE

.sp 1

In the above table,

.I servent

in

.I race:servent

signifies that if any of the functions

.BR setservent (),

.BR getservent (),

or

.BR endservent ()

are used in parallel in different threads of a program,

then data races could occur.

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008, 4.3BSD.

.SH SEE ALSO

.BR getnetent (3),

.BR getprotoent (3),

.BR getservent_r (3),

.BR services (5)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.