How do I get more information on how to use a command/application?

There are three main repositories of documentation in UNIX.

  • man - The UNIX Manual
  • info - The UNIX Information System
  • doc - The Documentation Tree

Note: You may also wish to visit our Documentation page.

For information about gcc, the GNU C Compiler, you would use:

man gcc

man displays pages of the UNIX manual (a multivolume documentation project) in a terminal, one page at a time. For a more graphical representation, use:


Xman is an X-Windows application for browsing man pages.

For detailed information about gcc, you would use:

info gcc

info is a hypertext viewer for information files. info files are more verbose and usually more complete than man pages. info pages are becoming the new standard in UNIX documentation.

The Documentation Tree is really just a directory that contains extended documentation for applications and projects. Typically the files in this directory are text files or Postscript files. For more information about gcc, you would go to the doc directory and look for a subdirectory for gcc and then look at the files within that directory:

ls -d gcc*
gcc-2.95.2           gcc-g77-2.95.2       gcc-objc-2.95.2
gcc-c++-2.95.2       gcc-java-2.95.2
gcc-colorgcc-2.95.2  gcc-libgcj-2.95.2
cd gcc-2.95.2
ChangeLog        FSFChangeLog.11  README.ALTOS     README.NS32K
ChangeLog.0      README           README.APOLLO    README.RS6000
ChangeLog.lib    README-bugs      README.C4X       README.TRAD
FSFChangeLog     README-fixinc    README.DWARF     README.X11