dh_installnss - enable NSS services

       Gioele Barabucci <gioele@svario.it>

perl v5.36.0                                       2022-11-01                                   DH_INSTALLNSS(1)

Non-standardNSSdatabases
       Directives in a package.nss file can reference a non-standard NSS database only if that database has been
       first declared with a "database-add" or "database-require" directive in the same file.

       Non-standard NSS databases are all databases that are not defined in /etc/nsswitch.conf as shipped by the
       package base-files.

       If a directive references an undeclared non-standard NSS database (e.g.,  "somedb"),  dh_installnss  will
       exit with the error message "Unknown NSS database 'somedb'".

       A  non-standard  NSS  database  can be declared by at most one installed package.  In other words, if the
       directives in the nss files of two packages A and B reference the same non-standard NSS database "somedb"
       and both packages can be installed at the  same  time,  one  of  the  following  two  solutions  must  be
       implemented:

       1.  Package A supplies the "somedb database-add" directive, package B Pre-Depends on A and uses a "somedb
           database-require" directive.

       2.  The shared package C supplies the "somedb database-add" directive, both package A and B Pre-Depend on
           C and use a "somedb database-require" directive.

dh_installnss is a debhelper program that is responsible for injecting NSS (Name Service Switch) services
       into /etc/nsswitch.conf.

       An example debian/nss file could look like this:

           hosts before=dns mdns4
           hosts before=mdns4 mdns4_minimal [NOTFOUND=return]
           hosts remove-only mdns    # In case the user manually added it

       After   the  installation  of  this  package,  the  original  configuration  of  the  hosts  database  in
       /etc/nsswitch.conf will change from:

           hosts:    files dns

       to:

           hosts:    files mdns4_minimal [NOTFOUND=return] mdns4 dns

       debian/package.nss
           Lists  the services to inject into /etc/nsswitch.conf when a package is configured and to remove when
           a package is removed or purged.

           Each line in that file (a directive) should be of the form

           dbpositionserviceactioncondition

           where the fields contain the following pieces of information:

           db  The NSS database in which the service will be added.  Usually "hosts".

           position
               Where to add the NSS service.

               Possible values are "first", "last", "before=service", "after=service", plus the pseudo-positions
               "remove-only", "database-add" and "database-require".

               The pseudo-position "remove-only" is used to mark services that are not going to be added  during
               the installation of the package, but that will be removed during its deinstallation (e.g., legacy
               services).

               The pseudo-position "database-add" is used to request the addition of a non-standard NSS database
               to  /etc/nsswitch.conf  during  the  installation  of  the  package  and  its  removal during the
               deinstallation of the package.  When "database-add" is used, all other fields  in  the  directive
               should be left empty.

               The  pseudo-position  "database-require" is used to announce that one or more services in the nss
               file will be installed under  a  non-standard  NSS  database  added  by  another  package.   When
               "database-require" is used, all other fields in the directive should be left empty.

           service
               The name of the NSS service to add.

           action
               Optional action specification "[STATE=ACTION]".

           condition
               Optional set of conditions to better define when a service should (or should not) be installed.

               Only one kind of condition is currently defined: "skip-if-present=service,service,...".

           Additionally, text between a "#" character and the end of line is ignored.

       dh_installnss - enable NSS services

debhelper(7)

       This program is a debhelper addon.

dh_installnss [debhelperoptions]