SunOS 4.x applications must be available on a Solaris 2.x system to use the binary compatibility packages. SunOS 4.x applications can be installed or mounted onto the Solaris 2.x system.
To install these applications, copy the executables in their original a.out format to the corresponding locations on the Solaris 2.x system. Applications can be copied using cp(1), rcp(1), tar(1), cpio(1), and so on. See the man Pages(1): User Commands in the Solaris 7 Reference Manual Collection for information on these commands.
In most cases, you should be able to install a 4.x application from the original distribution medium. Install scripts may require that /usr/ucb precede /usr/bin in the PATH variable to perform correctly.
It is also possible to mount SunOS 4.x directories on a Solaris 2.x system and execute binaries contained in them using the Binary Compatibility Package.
If the corresponding location does not already exist, or if there is a conflict with Solaris 2.x files, you may have to create directories, rename files, or resolve name conflicts individually.
All a.out shared object libraries required on the SunOS 4.x release, except for the SunOS and the Open Windows libraries, must be moved to Solaris 2.x or mounted. These libraries can be copied to the /usr/4lib directory. These libraries must retain the same major and minor version numbers they had in the SunOS 4.x release.
Environment variable LD_LIBRARY_PATH
Directories specified at link-time with the -L dir option to ld(1)ld(1)
Default directories: /usr/4lib:/usr/lib:/usr/local/lib
The /usr/4lib directory did not exist in SunOS 4.x. It is provided as a location for SunOS 4.x a.out libraries. This directory has been added to the default search rules so that compatibility package users can store their SunOS 4.x libraries there and be assured that the run-time linker will find them.