1nss(5)                        File Formats Manual                       nss(5)
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NAME

6       nss - Name Service Switch configuration file
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DESCRIPTION

10       Each  call  to  a  function which retrieves data from a system database
11       like the password or group database is  handled  by  the  Name  Service
12       Switch  implementation in the GNU C library.  The various services pro‐
13       vided are implemented by independent modules, each of  which  naturally
14       varies widely from the other.
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16       The  default  implementations  coming  with  the  GNU  C library are by
17       default conservative and do not use unsafe data.  This  might  be  very
18       costly  in  some  situations,  especially when the databases are large.
19       Some modules allow the system administrator to request taking shortcuts
20       if  these  are known to be safe.  It is then the system administrator's
21       responsibility to ensure the assumption is correct.
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23       There are other modules where the implementation changed over time.  If
24       an  implementation  used  to  sacrifize speed for memory consumption it
25       might create problems if the preference is switched.
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27       The /etc/default/nss file contains a number  of  variable  assignments.
28       Each  variable controls the behavior of one or more NSS modules.  White
29       spaces are ignored.  Lines beginning with `#' are treated as comments.
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31       The variables currently recognized are:
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33       NETID_AUTHORITATIVE = TRUE|FALSE
34              If set to TRUE, the NIS backend for the  initgroups(3)  function
35              will  accept  the  information  from the netid.byname NIS map as
36              authoritative.  This can speed up the function significantly  if
37              the  group.byname map is large.  The content of the netid.byname
38              map is used as is.  The system administrator has to make sure it
39              is correctly generated.
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42       SERVICES_AUTHORITATIVE = TRUE|FALSE
43              If  set  to  TRUE,  the NIS backend for the getservbyname(3) and
44              getservbyname_r(3) function will  assume  services.byservicename
45              NIS  map  exists and is authoritative, particularly that it con‐
46              tains both keys with /proto and without /proto for both  primary
47              service names and service aliases.  The system administrator has
48              to make sure it is correctly generated.
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51       SETENT_BATCH_READ = TRUE|FALSE
52              If set to TRUE, the NIS backend for  the  setpwent(3)  and  set‐
53              grent(3)  functions  will  read  the entire database at once and
54              then hand out the requests one by one  from  memory  with  every
55              corresponding  getpwent(3)  or  getgrent(3)  call  respectively.
56              Otherwise each getpwent(3) or getgrent(3) call might result into
57              a network communication with the server to get the next entry.
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EXAMPLE

62       The  default  configuration  corresponds to the following configuration
63       file:
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65       NETID_AUTHORITATIVE=FALSE
66       SERVICES_AUTHORITATIVE=FALSE
67       SETENT_BATCH_READ=FALSE
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FILES

72       /etc/default/nss
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AUTHOR

76       Ulrich Drepper <drepper@redhat.com>
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SEE ALSO

80       nsswitch.conf
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84nss                                May 2006                             nss(5)
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