In addition to man and pinfo, page developers may also include documentation in the application's RPM package. This documentation is installed on package installation and is conventionally stored in the /usr/share/doc/<packagename> directory. It contains any other relevant information that the developers want to share but that is not available in the man page of that package. You may find PDF, HTML, or TXT file-based documentation, license agreements, sample configuration files, and so on inside these directories.

Besides the preceding sources of documentation, if you have a GUI installed, then gnome-help or Khelpcenter are other sources of documentation available on the system. The online community of CentOS 7 also contains vast resources of documentation and help. Each Linux distribution has its own user-driven forums and Wiki sections.

The CentOS documentation is available at https://www.centos.org/docs/, but is being merged with the RHEL documentation at http://access.redhat.com, as CentOS has limited resources by comparison.

Some useful commands that give descriptions of other commands are as follows:

•  Whatis: This command displays a short description of binaries available in the Linux system. Its database is updated daily in CentOS 7 with the help of another command, makewhatis.
•  Whereis: This command locates the binary, source, and manual pages of the given command.
•  Which: This command takes one or more command names as argument, and returns the absolute path of the given command name.