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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 provided 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  prob‐
       lems 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 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 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

EXAMPLES
       The default configuration corresponds to the following configuration file:

           NETID_AUTHORITATIVE=FALSE
           SERVICES_AUTHORITATIVE=FALSE
           SETENT_BATCH_READ=FALSE

SEE ALSO
       nsswitch.conf

Linux                                                                          2020-06-09                                                                         NSS(5)