The most comprehensive documentation on FreeBSD is in the form of manual pages. Nearly every program on the system comes with a short reference manual explaining the basic operation and available arguments. These manuals can be viewed using man:

% man command

where command is the name of the command to learn about. For example, to learn more about ls(1), type:

% man ls

Manual pages are divided into sections which represent the type of topic. In FreeBSD, the following sections are available:

In some cases, the same topic may appear in more than one section of the online manual. For example, there is a chmod user command and a chmod() system call. To tell man(1) which section to display, specify the section number:

% man 1 chmod

This will display the manual page for the user command chmod(1). References to a particular section of the online manual are traditionally placed in parenthesis in written documentation, so chmod(1) refers to the user command and chmod(2) refers to the system call.

If the name of the manual page is unknown, use man -k to search for keywords in the manual page descriptions:

% man -k mail

This command displays a list of commands that have the keyword “mail” in their descriptions. This is equivalent to using apropos(1).

To read the descriptions for all of the commands in /usr/bin, type:

% cd /usr/bin
% man -f * | more

or

% cd /usr/bin
% whatis * |more

% info