1.\" $NetBSD: nsswitch.conf.5,v 1.14 1999/03/17 20:19:47 garbled Exp $ 2.\" $FreeBSD$ 3.\" 4.\" Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc. 5.\" All rights reserved. 6.\" 7.\" This code is derived from software contributed to The NetBSD Foundation 8.\" by Luke Mewburn. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by Luke Mewburn. 21.\" 4. The name of the author may not be used to endorse or promote products 22.\" derived from this software without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 29.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 30.\" OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 31.\" ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR 32.\" TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE 33.\" USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34.\" 35.Dd January 22, 1998 36.Dt NSSWITCH.CONF 5 37.Os 38.Sh NAME 39.Nm nsswitch.conf 40.Nd name-service switch configuration file 41.Sh DESCRIPTION 42The 43.Nm 44file specifies how the 45.Xr nsdispatch 3 46(name-service switch dispatcher) routines in the C library should operate. 47.Pp 48The configuration file controls how a process looks up various databases 49containing information regarding hosts, users (passwords), groups, etc. 50Each database comes from a source (such as local files, DNS, and 51.Tn NIS ) , 52and the order to look up the sources is specified in 53.Nm . 54.Pp 55Each entry in 56.Nm 57consists of a database name, and a space separated list of sources. 58Each source can have an optional trailing criterion that determines 59whether the next listed source is used, or the search terminates at 60the current source. 61Each criterion consists of one or more status codes, and actions to 62take if that status code occurs. 63.Ss Sources 64The following sources are implemented: 65.Pp 66.Bl -tag -width Source -compact 67.It Sy Source 68.Sy Description 69.It files 70Local files, such as 71.Pa /etc/hosts , 72and 73.Pa /etc/passwd . 74.It dns 75Internet Domain Name System. 76.Dq hosts 77and 78.Sq networks 79use 80.Sy IN 81class entries, all other databases use 82.Sy HS 83class (Hesiod) entries. 84.It nis 85NIS (formerly YP) 86.It compat 87support 88.Sq +/- 89in the 90.Dq passwd 91and 92.Dq group 93databases. 94If this is present, it must be the only source for that entry. 95.El 96.Ss Databases 97The following databases are used by the following C library functions: 98.Pp 99.Bl -tag -width networks -compact 100.It Sy Database 101.Sy "Used by" 102.It group 103.Xr getgrent 3 104.It hosts 105.Xr gethostbyname 3 106.It networks 107.Xr getnetbyname 3 108.It passwd 109.Xr getpwent 3 110.It shells 111.Xr getusershell 3 112.El 113.Ss Status codes 114The following status codes are available: 115.Pp 116.Bl -tag -width tryagain -compact 117.It Sy Status 118.Sy Description 119.It success 120The requested entry was found. 121.It notfound 122The entry is not present at this source. 123.It tryagain 124The source is busy, and may respond to retries. 125.It unavail 126The source is not responding, or entry is corrupt. 127.El 128.Ss Actions 129For each of the status codes, one of two actions is possible: 130.Pp 131.Bl -tag -width continue -compact 132.It Sy Action 133.Sy Description 134.It continue 135Try the next source 136.It return 137Return with the current result 138.El 139.Ss Format of file 140A 141.Tn BNF 142description of the syntax of 143.Nm 144is: 145.Pp 146.Bl -tag -width <criterion> -compact 147.It <entry> 148::= 149<database> ":" [<source> [<criteria>]]* 150.It <criteria> 151::= 152"[" <criterion>+ "]" 153.It <criterion> 154::= 155<status> "=" <action> 156.It <status> 157::= 158"success" | "notfound" | "unavail" | "tryagain" 159.It <action> 160::= 161"return" | "continue" 162.El 163.Pp 164Each entry starts on a new line in the file. 165A 166.Sq # 167delimits a comment to end of line. 168Blank lines are ignored. 169A 170.Sq \e 171at the end of a line escapes the newline, and causes the next line to 172be a continuation of the current line. 173All entries are case-insensitive. 174.Pp 175The default criteria is to return on 176.Dq success , 177and continue on anything else (i.e, 178.Li [success=return notfound=continue unavail=continue tryagain=continue] 179). 180.Ss Compat mode: +/- syntax 181In historical multi-source implementations, the 182.Sq + 183and 184.Sq - 185characters are used to specify the importing of user password and 186group information from 187.Tn NIS . 188Although 189.Nm 190provides alternative methods of accessing distributed sources such as 191.Tn NIS , 192specifying a sole source of 193.Dq compat 194will provide the historical behaviour. 195.Pp 196An alternative source for the information accessed via 197.Sq +/- 198can be used by specifying 199.Dq passwd_compat: source . 200.Dq source 201in this case can be 202.Sq dns , 203.Sq nis , 204or 205any other source except for 206.Sq files 207and 208.Sq compat . 209.Ss Notes 210Historically, many of the databases had enumeration functions, often of 211the form 212.Fn getXXXent . 213These made sense when the databases were in local files, but don't make 214sense or have lesser relevance when there are possibly multiple sources, 215each of an unknown size. 216The interfaces are still provided for compatibility, but the source 217may not be able to provide complete entries, or duplicate entries may 218be retrieved if multiple sources that contain similar information are 219specified. 220.Pp 221To ensure compatibility with previous and current implementations, the 222.Dq compat 223source must appear alone for a given database. 224.Ss Default source lists 225If, for any reason, 226.Nm 227doesn't exist, or it has missing or corrupt entries, 228.Xr nsdispatch 3 229will default to an entry of 230.Dq files 231for the requested database. 232Exceptions are: 233.Pp 234.Bl -tag -width passwd_compat -compact 235.It Sy Database 236.Sy "Default source list" 237.It group 238compat 239.It group_compat 240nis 241.It hosts 242dns files 243.It passwd 244compat 245.It passwd_compat 246nis 247.El 248.Sh FILES 249.Bl -tag -width /etc/nsswitch.conf -compact 250.It Pa /etc/nsswitch.conf 251The file 252.Nm 253resides in 254.Pa /etc . 255.El 256.Sh EXAMPLES 257To lookup hosts in 258.Pa /etc/hosts 259and then from the DNS, and lookup user information from 260.Tn NIS 261then files, use: 262.Pp 263.Bl -tag -width passwd: -compact 264.It hosts: 265files dns 266.It passwd: 267nis [notfound=return] files 268.It group: 269nis [notfound=return] files 270.El 271.Pp 272The criteria 273.Dq [notfound=return] 274sets a policy of "if the user is notfound in nis, don't try files." 275This treats nis as the authoritive source of information, except 276when the server is down. 277.Sh SEE ALSO 278.Xr nsdispatch 3 , 279.Xr resolv.conf 5 , 280.Xr named 8 , 281.Xr ypbind 8 282.Sh HISTORY 283The 284.Nm 285file format first appeared in 286.Fx 4.1 . 287It was imported from the 288.Nx 289Project, where it appeared first in 290.Nx 1.4 . 291.Sh AUTHORS 292Luke Mewburn 293.Aq lukem@netbsd.org 294wrote this freely distributable name-service switch implementation, 295using ideas from the 296.Tn ULTRIX 297.Xr svc.conf 5 298and 299.Tn Solaris 300.Xr nsswitch.conf 4 301manual pages. 302