1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" From: @(#)getservent.3 8.3 (Berkeley) 1/12/94 29.\" 30.Dd December 7, 2020 31.Dt GETSERVENT 3 32.Os 33.Sh NAME 34.Nm getservent , 35.Nm getservbyport , 36.Nm getservbyname , 37.Nm setservent , 38.Nm endservent 39.Nd get service entry 40.Sh LIBRARY 41.Lb libc 42.Sh SYNOPSIS 43.In netdb.h 44.Ft struct servent * 45.Fn getservent 46.Ft struct servent * 47.Fn getservbyname "const char *name" "const char *proto" 48.Ft struct servent * 49.Fn getservbyport "int port" "const char *proto" 50.Ft void 51.Fn setservent "int stayopen" 52.Ft void 53.Fn endservent void 54.Sh DESCRIPTION 55The 56.Fn getservent , 57.Fn getservbyname , 58and 59.Fn getservbyport 60functions 61each return a pointer to an object with the 62following structure 63containing the broken-out 64fields of a line in the network services data base, 65.Pa /etc/services . 66.Bd -literal -offset indent 67struct servent { 68 char *s_name; /* official name of service */ 69 char **s_aliases; /* alias list */ 70 int s_port; /* port service resides at */ 71 char *s_proto; /* protocol to use */ 72}; 73.Ed 74.Pp 75The members of this structure are: 76.Bl -tag -width s_aliases 77.It Fa s_name 78The official name of the service. 79.It Fa s_aliases 80A zero terminated list of alternate names for the service. 81.It Fa s_port 82The port number at which the service resides. 83Port numbers are returned in network byte order. 84.It Fa s_proto 85The name of the protocol to use when contacting the 86service. 87.El 88.Pp 89The 90.Fn getservent 91function 92reads the next line of the file, opening the file if necessary. 93.Pp 94The 95.Fn setservent 96function 97opens and rewinds the file. 98If the 99.Fa stayopen 100flag is non-zero, 101the net data base will not be closed after each call to 102.Fn getservbyname 103or 104.Fn getservbyport . 105.Pp 106The 107.Fn endservent 108function 109closes the file. 110.Pp 111The 112.Fn getservbyname 113and 114.Fn getservbyport 115functions 116sequentially search from the beginning 117of the file until a matching 118protocol name or 119port number (which must be specified in 120network byte order) is found, 121or until 122.Dv EOF 123is encountered. 124If a protocol name is also supplied (non- 125.Dv NULL ) , 126searches must also match the protocol. 127.Sh FILES 128.Bl -tag -width /etc/services -compact 129.It Pa /etc/services 130.It Pa /var/db/services.db 131.El 132.Sh DIAGNOSTICS 133Null pointer returned on 134.Dv EOF 135or error. 136.Sh SEE ALSO 137.Xr getprotoent 3 , 138.Xr services 5 , 139.Xr services_mkdb 8 140.Sh HISTORY 141The 142.Fn getservent , 143.Fn getservbyport , 144.Fn getservbyname , 145.Fn setservent , 146and 147.Fn endservent 148functions appeared in 149.Bx 4.2 . 150.Sh BUGS 151These functions use a thread-specific data storage; 152if the data is needed for future use, it should be 153copied before any subsequent calls overwrite it. 154Expecting port numbers to fit in a 32 bit 155quantity is probably naive. 156