Onsight Unix Manual

The command man is the most important command in the Unix system: it brings up the online documentation which detail every command available on the system. The most basic syntax for the command is
       man command
This will display the documentation for command using the Unix more command, which displays the file one screen at a time (about ten lines.) To scroll through the documentation you use basic man commands:

key	action
SPACE	display next screen of text
b	skip backward one screen of text
DOWN_ARROW	move down one line
UP_ARROW	move up one line
p	go back to the beginning of the document
/pattern	search for next occurrence of pattern
/	search for next occurrence of last pattern entered
q	quit

Each page of the manual contains the documentation for an item (Unix command, system call, system information) and is called a manpage or title page. And each manpage is divided into several sections. In the usual order of occurrence these are:

Section	Contents
NAME	the name of the command and a brief description of its action
SYNOPSIS	the syntax of the command:    for Unix commands this is the command line form    for C functions this includes all header files needed as well as the function prototype
DESCRIPTION	detailed description of the action of the function, each argument, and the return value of the action
ERRORS	a list of each value that errno might be set as well as the cause of the error
SEE ALSO	other related manpage entries as well as their location in the manpage
HISTORY	A brief account of where the function arose.

The manual is also divided into eight or nine sections. This is very important to keep in mind: some commands may occur in several sections. For example, open occurs as both a Unix command as well as a system call, and these occur in separate sections. A simple call
       man open
will only display the Unix command, since it occurs earlier in the manual then the manpage for the system call. If a command or function has a title in the manpage documentation, this will be listed in paratheses: open(1) or open(2).

Section Number	Description
1	Executable programs which can be executed on the command line.
2	System calls provided by the kernel.
3	Library calls for programmers.
4	Special files for device drivers and network interfaces.
5	File formats and conventions (e.g. /etc/passwd)
6	Game documentation
7	Miscellaneous documentation such as ASCII tables
8	System administration commands for a privileged user
9	Kernel routines

• man [section] title
  • This calls-up the manpage for the title in section (if one is specified) or the first manpage for the title. Recall, that some commands may have several entries in the manual.

• man -k string
  equivalently, apropos string
  • searches the manual page DESCRIPTION section for all occurences of string and prints the description. The string may be embedded in a word.

• man -f   word
  equivalently, whatis word
  • searches the manual page DESCRIPTION section for all occurences of the word word and prints the description

• whatis  word |grep string
  apropos  string |grep string
  • refine the manpage search for string, and return only those lines in which string occurs. This is useful if you want to narrow your search. For example, compare
        apropos  open
        apropos  open  | grep 2

Finally, you too can add entries to the manual pages (there is nothing sacrosanct about them!!!) Have a look at the manual page for man and see if you can figure-out how to call-up a manual page documenting one of your own functions.