This is a NSS module which can read user information from files
in the same format as /etc/passwd and /etc/group stored in an
alternate location (/lib by default).
As of version 2.19.0, the module supports also files mimicking
other files from /etc, and which file types are supported can
be selected at build time:
/etc/rpc/etc/protocols/etc/hosts/etc/networks/etc/services/etc/shadow/etc/gshadow
Essentially, it is a tweaked copy of the sources for the NSS
files module included with glibc2
(or eglibc in versions prior to 2.19.0).
List the module the /etc/nsswitch.conf configuration file.
For example:
passwd: files altfiles
group: files altfiles
# Other entries follow...
This will try to read files from /etc first, and under
/lib (using the altfiles module). Modifications will be
stored in the files under /etc (e.g. when using passwd
to change an user passwords).
The usual ./configure && make && make install dance will
work. The configure script allows to change the install
path and the path to the alternative data files:
./configure --prefix=/installdir/path --datadir=/var
To select which file types will be supported, use the
--with-types=FOO flag:
./configure --with-types=pwd,grp,hosts
The example above would build an altfiles NSS module that
will read user information from /var/passwd and /var/group,
which is to be installed under /installdir/path/lib.
To ease the task of packagers, the DESTDIR variable can
be passed to make:
make install DESTDIR=/tmp/fakerootdir
Version numbers follow the numbering of the eglibc releases,
adding a local revision number: <eglibc version>.<revision>.
For example version 2.13.0 would contain the source files
from eglibc 2.13, and the base modifications to make it the
altfiles module; version 2.15.3 would contain the source
files from eglibc 2.15, and the base modifications plus three
patches.
Starting from version 2.19.0, version numbers follow glibc2 versions, as eglibc is no longer developed because its changes were merged back into glibc2.
Git tags do also follow this versioning.
As eglibc and glibc are distributed under the terms of the
LGPL 2.1, the same applies to the extra bits needed to make
nss_altfiles work.
See the COPYING file in the source directory for the full text of the license.