Filesystem Hierarchy Standard

Tree 3.8.1

/opt is reserved for the installation of add-on application software packages.

A package to be installed in /opt shall locate its static files in a separate /opt/<package> directory tree, where <package> is a name that describes the software package.

Programs to be invoked by users shall be located in the directory /opt/<package>/bin. If the package includes UNIX manual pages, they shall be located in /opt/<package>/man and the same substructure as /usr/share/man shall be used.

The directories /opt/bin, /opt/doc, /opt/include, /opt/info, /opt/lib, and /opt/man 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 by the local system administrator, but shall function normally in the absence of these reserved directories.

Package files that are variable (change in normal operation) should be installed in /var/opt. See the section on /var/opt for more information.

Host-specific configuration files should be installed in /etc/opt. See the section on /etc for more information.

No other package files should 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 must be placed in /var/lock and devices must be located in /dev.

Distributions may install software in /opt, but should not modify or delete software installed by the local system administrator without the assent of the local system administrator.

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The Intel Binary Compatibility Standard v. 2 (iBCS2) also provides a similar structure for /opt.

Generally, all data required to support a package on a system should be present within /opt/<package>, including files intended to be copied into /etc/opt/<package> and /var/opt/<package> 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.

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