4.13 For More Information

4.13.1 Manual Pages

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 various arguments. These manuals can be viewed with the man command. Use of the man command is simple:

% man command

command is the name of the command you wish to learn about. For example, to learn more about ls command type:

% man ls

The online manual is divided up into numbered sections:

1. User commands.

2. System calls and error numbers.

3. Functions in the C libraries.

4. Device drivers.

5. File formats.

6. Games and other diversions.

7. Miscellaneous information.

8. System maintenance and operation commands.

9. Kernel developers.

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. In this case, you can tell the man command which one you want by specifying the section:

% man 1 chmod

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

This is fine if you know the name of the command and just wish to know how to use it, but what if you cannot recall the command name? You can use man to search for keywords in the command descriptions by using the -k switch:

% man -k mail

With this command you will be presented with a list of commands that have the keyword “mail” in their descriptions. This is actually functionally equivalent to using the apropos command.

So, you are looking at all those fancy commands in /usr/bin but do not have the faintest idea what most of them actually do? Type:

% cd /usr/bin
% man -f *

or

% cd /usr/bin
% whatis *

which does the same thing.

4.13.2 GNU Info Files

FreeBSD includes many applications and utilities produced by the Free Software Foundation (FSF). In addition to manual pages, these programs come with more extensive hypertext documents called info files which can be viewed with the info command or, if you installed emacs, the info mode of emacs.

To use the info(1) command, type:

% info

For a brief introduction, type h. For a quick command reference, type ?.