Man Pages

nss(5) - phpMan nss(5) - phpMan

Command: man perldoc info search(apropos)  


nss(5)                                                                  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 han-
       dled by the Name Service Switch implementation in the GNU C library.  The various services provided are  imple-
       mented 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 sys-
       tem administrator's responsibility to ensure the assumption is correct.

       There are other modules where the implementation changed over time.  If an  implementation  used  to  sacrifize
       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) function will assume
              services.byservicename NIS map exists and is authoritative, particularly 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  setgrent(3)  functions  will  read  the  entire
              database  at  once  and then hand out the requests one by one from memory with every corresponding getp-
              went(3) or getgrent(3) call respectively.  Otherwise each getpwent(3) or getgrent(3) call  might  result
              into a network communication with the server to get the next entry.



EXAMPLE
       The default configuration corresponds to the following configuration file:

       NETID_AUTHORITATIVE=FALSE
       SERVICES_AUTHORITATIVE=FALSE
       SETENT_BATCH_READ=FALSE



FILES
       /etc/default/nss


AUTHOR
       Ulrich Drepper <drepperATredhat.com>


SEE ALSO
       nsswitch.conf



nss                                May 2006                             nss(5)