Some of the differences you will find in migrating to the SunOS 5.x environment from a SunOS 4.x environment are:
Solaris 2.5 software can be installed on SPARC systems only from a local or remote CD-ROM drive or from a network.
Solaris 2.5 software media is distributed in software groups, made up of packages and clusters, which facilitates installation. For the most up-to-date information on Solaris 2.5 packages use pkginfo(1) or swmtool.
Device-naming conventions have changed; disks, for example, are now named as follows:
Note that on some disks (xy, xd) there is no target component; such disks have names like c0d0s0.
The file system directory structure has changed. For example:
The kernel, called unix, and its related modules are stored in the /kernel directory.
The /opt directory is a new directory. It is created during installation for storing or mounting optional software applications.
The /devices directory is a hierarchy of device files, with symbolic links into the /dev directory for compatibility with the SunOS 4.x device naming conventions.
The Remote File Sharing service (RFS) optional software package has been discontinued since Solaris 2.2.
The SunOS 5.x kernel is dynamic; the user no longer rebuilds or edits the kernel configuration file.
The kernel can automatically load necessary drivers for new devices added to the system.
The Solaris 2.5 startup and shutdown procedures have changed:
The init(1M)command uses different scripts for each run level.
The shutdown command does not support any of the options available in SunOS 4.1 systems.
The fastboot(1B) and fasthalt(1b) commands are only available using the SunOS/BSD Source Compatibility Package.
Many commands have changed, as well as the output from commands. Scripts may need to be rewritten. For more information, see Solaris 1.x to 2.x Transition Guide.
NIS+ replaces the NIS, the Network Information Service name service; however, NIS+ uses NIS data, which makes it easier to transition to NIS+.
Administration Tool (admintool), Motif application that allows you to administer your local system, provides management of system database and host information, printers, serial ports, user accounts, and software.
The print management commands have changed. For a detailed list, see Solaris 1.x to 2.x Transition Guide.
Terminals and modems are controlled through the Service Access Facility (SAF) and System Access Controller (SAC); the /etc/ttytab file is gone.