1.17. /opt

This directory is reserved for all the software and add-on packages that are not part of the default installation. For example, StarOffice, Kylix, Netscape Communicator and WordPerfect packages are normally found here. To comply with the FSSTND, all third party applications should be installed in this directory. Any package to be installed here must locate its static files (ie. extra fonts, clipart, database files) in a separate /opt/'package-name' directory tree (similar to the way in which Windows will install new software to its own directory tree C:\Windows\Progam Files\"Program Name"), where 'package-name' is a name that describes the software package.

Although most distributions neglect to create the directories /opt/bin, /opt/doc, /opt/include, /opt/info, /opt/lib, and /opt/man they are reserved for local system administrator use. Packages may provide "front-end" files intended to be placed in (by linking or copying) these reserved directories, but must function normally in the absence of these reserved directories. Programs to be invoked by users are located in the directory /opt/'package-name'/bin. If the package includes UNIX manual pages, they are located in /opt/'package-name'/man and the same substructure as /usr/share/man must be used. Package files that are variable must be installed in /var/opt. Host-specific configuration files are installed in /etc/opt.

Under no circumstances are other package files to exist outside the /opt, /var/opt, and /etc/opt hierarchies except for those package files that must reside in specific locations within the filesystem tree in order to function properly. For example, device lock files in /var/lock and devices in /dev. Distributions may install software in /opt but this is not recommended practice.

The use of /opt for add-on software is a well-established practice in the UNIX community. The System V Application Binary Interface [AT&T 1990], based on the System V Interface Definition (Third Edition) and the Intel Binary Compatibility Standard v. 2 (iBCS2) provides for an /opt structure very similar to the one defined here.

Generally, all data required to support a package on a system must be present within /opt/'package-name', including files intended to be copied into /etc/opt/'package-name' and /var/opt/'package-name' as well as reserved directories in /opt. The minor restrictions on distributions using /opt are necessary because conflicts are possible between distribution installed and locally installed software, especially in the case of fixed pathnames found in some binary software.