NIS supports password configuration files in both the SunOS 4 (Solaris 1) password format and the Solaris 2 password and shadow file formats.
The mode of operation is determined by the existence of the file $PWDIR/shadow, where
is the Makefile macro set in the /var/yp/Makefile file. If the shadow file exists, NIS operates
in the Solaris 2 mode. If this file does not exist, NIS operates in the SunOS
In the SunOS 4 mode, all password information is kept in the passwd file. In the Solaris 2 mode, password information is kept in the shadow file and the user account information is kept in the passwd file.
If the make macro
is set to the /etc directory, NIS can operate only in
the Solaris 2 mode because of the Solaris 2 passwd processing
requirements. However, if
PWDIR points to any directory
other than /etc, the user has the option of keeping passwd configuration files in either the SunOS 4 format or in the
Solaris 2 format. The rpc.yppasswdd daemon understands
both password formats. The Solaris 2 format is recommended.