This actually relates to File System Hierarchy Standard. Even if you consider using your own application
, for achieving its better integration based on its customized segregation , it is defined in /opt : Add-on application software packages as
The directories /opt/bin, /opt/doc, /opt/include, /opt/info, /opt/lib,
and /opt/man are reserved for local system administrator(USER) 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 must function normally in the absence of these reserved
Programs to be invoked by users must be located in the directory
/opt//bin or under the /opt/ hierarchy. If the
package includes UNIX manual pages, they must be located in
/opt//share/man or under the /opt/ hierarchy, and
the same substructure as /usr/share/man must be used.
Package files that are variable (change in normal operation) must be
installed in /var/opt. See the section on /var/opt for more
Host-specific configuration files must be installed in /etc/opt. See
the section on /etc for more information.
No other package files may 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 must not modify or
delete software installed by the local system administrator without
the assent of the local system administrator.
Following this format for custom applications is better supported by the Ubuntu /Linux system .Further ..
Rationale or Fundamental Reason behind it
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),
provides for an /opt structure very similar to the one defined here.
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 must be
present within /opt/, including files intended to be copied
into /etc/opt/ and /var/opt/ 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.
The structure of the directories below /opt/ is left up to
the packager of the software, though it is recommended that packages
are installed in /opt// and follow a similar
structure to the guidelines for /opt/package. A valid reason for
diverging from this structure is for support packages which may have
files installed in /opt//lib or /opt//bin