156 lines
4.1 KiB
Groff
156 lines
4.1 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" From: @(#)getservent.3 8.3 (Berkeley) 1/12/94
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.\" $FreeBSD$
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.\"
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.Dd July 9, 1995
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.Dt GETSERVENT 3
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.Os
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.Sh NAME
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.Nm getservent ,
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.Nm getservbyport ,
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.Nm getservbyname ,
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.Nm setservent ,
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.Nm endservent
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.Nd get service entry
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In netdb.h
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.Ft struct servent *
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.Fn getservent
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.Ft struct servent *
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.Fn getservbyname "const char *name" "const char *proto"
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.Ft struct servent *
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.Fn getservbyport "int port" "const char *proto"
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.Ft void
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.Fn setservent "int stayopen"
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.Ft void
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.Fn endservent void
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.Sh DESCRIPTION
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The
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.Fn getservent ,
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.Fn getservbyname ,
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and
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.Fn getservbyport
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functions
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each return a pointer to an object with the
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following structure
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containing the broken-out
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fields of a line in the network services data base,
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.Pa /etc/services .
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.Bd -literal -offset indent
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struct servent {
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char *s_name; /* official name of service */
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char **s_aliases; /* alias list */
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int s_port; /* port service resides at */
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char *s_proto; /* protocol to use */
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};
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.Ed
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.Pp
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The members of this structure are:
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.Bl -tag -width s_aliases
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.It Fa s_name
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The official name of the service.
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.It Fa s_aliases
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A zero terminated list of alternate names for the service.
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.It Fa s_port
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The port number at which the service resides.
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Port numbers are returned in network byte order.
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.It Fa s_proto
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The name of the protocol to use when contacting the
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service.
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.El
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.Pp
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The
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.Fn getservent
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function
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reads the next line of the file, opening the file if necessary.
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.Pp
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The
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.Fn setservent
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function
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opens and rewinds the file.
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If the
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.Fa stayopen
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flag is non-zero,
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the net data base will not be closed after each call to
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.Fn getservbyname
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or
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.Fn getservbyport .
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.Pp
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The
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.Fn endservent
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function
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closes the file.
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.Pp
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The
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.Fn getservbyname
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and
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.Fn getservbyport
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functions
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sequentially search from the beginning
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of the file until a matching
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protocol name or
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port number (which must be specified in
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network byte order) is found,
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or until
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.Dv EOF
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is encountered.
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If a protocol name is also supplied (non-
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.Dv NULL ) ,
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searches must also match the protocol.
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.Sh FILES
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.Bl -tag -width /etc/services -compact
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.It Pa /etc/services
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.El
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.Sh DIAGNOSTICS
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Null pointer
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(0) returned on
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.Dv EOF
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or error.
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.Sh SEE ALSO
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.Xr getprotoent 3 ,
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.Xr services 5
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.Sh HISTORY
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The
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.Fn getservent ,
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.Fn getservbyport ,
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.Fn getservbyname ,
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.Fn setservent ,
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and
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.Fn endservent
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functions appeared in
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.Bx 4.2 .
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.Sh BUGS
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These functions use a thread-specific data storage;
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if the data is needed for future use, it should be
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copied before any subsequent calls overwrite it.
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Expecting port numbers to fit in a 32 bit
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quantity is probably naive.
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