NSS(5)			   Linux Programmer's Manual			NSS(5)



NAME
       nss - Name Service Switch configuration file

DESCRIPTION
       Each  call  to  a  function which retrieves data from a system database
       like the password or group database is  handled	by  the	 Name  Service
       Switch  implementation in the GNU C library.  The various services pro-
       vided are implemented by independent modules, each of  which  naturally
       varies widely from the other.

       The  default  implementations  coming  with  the	 GNU  C library are by
       default conservative and do not use unsafe data.	 This  might  be  very
       costly  in  some	 situations,  especially when the databases are large.
       Some modules allow the system administrator to request taking shortcuts
       if  these  are known to be safe.	 It is then the system administrator's
       responsibility to ensure the assumption is correct.

       There are other modules where the implementation changed over time.  If
       an  implementation  used	 to sacrifice speed for memory consumption, it
       might create problems if the preference is switched.

       The /etc/default/nss file contains a number  of	variable  assignments.
       Each  variable controls the behavior of one or more NSS modules.	 White
       spaces are ignored.  Lines beginning with '#' are treated as comments.

       The variables currently recognized are:

       NETID_AUTHORITATIVE = TRUE|FALSE
	      If set to TRUE, the NIS backend for the  initgroups(3)  function
	      will  accept  the	 information  from the netid.byname NIS map as
	      authoritative.  This can speed up the function significantly  if
	      the  group.byname map is large.  The content of the netid.byname
	      map is used as is.  The system administrator has to make sure it
	      is correctly generated.

       SERVICES_AUTHORITATIVE = TRUE|FALSE
	      If  set  to  TRUE,  the NIS backend for the getservbyname(3) and
	      getservbyname_r(3)  functions  will   assume   that   the	  ser-
	      vices.byservicename NIS map exists and is authoritative, partic-
	      ularly that it contains both keys with /proto and without /proto
	      for  both primary service names and service aliases.  The system
	      administrator has to make sure it is correctly generated.

       SETENT_BATCH_READ = TRUE|FALSE
	      If set to TRUE, the NIS backend for  the	setpwent(3)  and  set-
	      grent(3)	functions  will	 read  the entire database at once and
	      then hand out the requests one by one  from  memory  with	 every
	      corresponding  getpwent(3)  or  getgrent(3)  call	 respectively.
	      Otherwise, each getpwent(3) or getgrent(3) call might result  in
	      a network communication with the server to get the next entry.

FILES
       /etc/default/nss

EXAMPLE
       The  default  configuration  corresponds to the following configuration
       file:

       NETID_AUTHORITATIVE=FALSE
       SERVICES_AUTHORITATIVE=FALSE
       SETENT_BATCH_READ=FALSE

SEE ALSO
       nsswitch.conf

COLOPHON
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       latest	 version    of	  this	  page,	   can	   be	  found	    at
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Linux				  2013-02-13				NSS(5)