1 .\" $NetBSD: nsswitch.conf.5,v 1.14 1999/03/17 20:19:47 garbled Exp $
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41 .Nd name-service switch configuration file
45 file specifies how the
47 (name-service switch dispatcher) routines in the C library should operate.
49 The configuration file controls how a process looks up various databases
50 containing information regarding hosts, users (passwords), groups, etc.
51 Each database comes from a source (such as local files, DNS,
53 and cache), and the order to look up the sources is specified in
58 consists of a database name, and a space separated list of sources.
59 Each source can have an optional trailing criterion that determines
60 whether the next listed source is used, or the search terminates at
62 Each criterion consists of one or more status codes, and actions to
63 take if that status code occurs.
65 The following sources are implemented as part of the base system:
67 .Bl -tag -width Source -compact
78 Internet Domain Name System.
84 class entries, all other databases use
86 class (Hesiod) entries.
97 If this is present, it must be the only source for that entry.
104 Additional sources might be provided by third party software.
106 The following databases are used by the following C library functions:
108 .Bl -tag -width networks -compact
120 .Xr gethostbyaddr 3 ,
121 .Xr gethostbyaddr_r 3 ,
122 .Xr gethostbyname 3 ,
123 .Xr gethostbyname2 3 ,
124 .Xr gethostbyname_r 3 ,
125 .Xr getipnodebyaddr 3 ,
126 .Xr getipnodebyname 3
129 .Xr getnetbyaddr_r 3 ,
145 .Xr getrpcbynumber 3 ,
148 .Xr getprotobyname 3 ,
149 .Xr getprotobynumber 3 ,
153 .Xr getnetgrent_r 3 ,
159 The following status codes are available:
161 .Bl -tag -width tryagain -compact
165 The requested entry was found.
167 The entry is not present at this source.
169 The source is busy, and may respond to retries.
171 The source is not responding, or entry is corrupt.
174 For each of the status codes, one of two actions is possible:
176 .Bl -tag -width continue -compact
182 Return with the current result
187 description of the syntax of
191 .Bl -tag -width <criterion> -compact
194 <database> ":" [<source> [<criteria>]]*
200 <status> "=" <action>
203 "success" | "notfound" | "unavail" | "tryagain"
206 "return" | "continue"
209 Each entry starts on a new line in the file.
212 delimits a comment to end of line.
213 Blank lines are ignored.
216 at the end of a line escapes the newline, and causes the next line to
217 be a continuation of the current line.
218 All entries are case-insensitive.
220 The default criteria is to return on
222 and continue on anything else (i.e,
223 .Li "[success=return notfound=continue unavail=continue tryagain=continue]" ) .
225 You can enable caching for the particular database by specifying
227 as the first source in the
230 You should also enable caching for this database in
232 If for the particular query
234 source returns success, no further sources are queried.
235 On the other hand, if there are no previously cached data, the
236 query result will be placed into the cache right after
237 all other sources are processed.
242 daemon to be running.
243 .Ss Compat mode: +/- syntax
244 In historical multi-source implementations, the
248 characters are used to specify the importing of user password and
249 group information from
253 provides alternative methods of accessing distributed sources such as
255 specifying a sole source of
257 will provide the historical behaviour.
259 An alternative source for the information accessed via
261 can be used by specifying
262 .Dq passwd_compat: source .
268 any other source except for
273 Historically, many of the databases had enumeration functions, often of
276 These made sense when the databases were in local files, but do not make
277 sense or have lesser relevance when there are possibly multiple sources,
278 each of an unknown size.
279 The interfaces are still provided for compatibility, but the source
280 may not be able to provide complete entries, or duplicate entries may
281 be retrieved if multiple sources that contain similar information are
284 To ensure compatibility with previous and current implementations, the
286 source must appear alone for a given database.
287 .Ss Default source lists
290 does not exist, or it has missing or corrupt entries,
292 will default to an entry of
294 for the requested database.
297 .Bl -tag -width services_compat -compact
299 .Sy "Default source list"
316 .Bl -tag -width /etc/nsswitch.conf -compact
317 .It Pa /etc/nsswitch.conf
324 To lookup hosts in cache, then in
326 and then from the DNS, and lookup user information from
330 .Bl -tag -width passwd: -compact
334 nis [notfound=return] files
336 nis [notfound=return] files
340 .Dq [notfound=return]
341 sets a policy of "if the user is notfound in nis, do not try files."
342 This treats nis as the authoritative source of information, except
343 when the server is down.
347 file is parsed by each program only once.
348 Subsequent changes will not be applied until the program
351 If system got compiled with
359 provides stubs for compatibility with NSS modules
365 However, these stubs only support the use of the
379 file format first appeared in
381 It was imported from the
383 Project, where it appeared first in
386 .An Luke Mewburn Aq Mt lukem@netbsd.org
387 wrote this freely distributable name-service switch implementation,