The man is divided into several sections. The first three are the most commonly used.
% man man
To view a manual page for a command or library function, just type man followed by the command:
% man toupperSometimes the same name is used for a command and a function. In this case you can get the correct man page by specifying the part of the manual in which it is contained. For example, to get the man page for the system call write, which appears in section 2 of the manual, I'd type:
% man 2 writeSome of the manual sections are:
1 Commands: Those commands that are typed in at the Unix shell prompt. 2 System calls: Those functions which must be performed by the kernel. 3 Library calls: Library functions (ex. man pages for C library functions) (note: for languages other than C, man pages may or may not exist for their libraries)
The man page is opened in a program named less. You can quit by typing 'q', and move down a page by typing the space bar, or use the arrow keys. For more information on using less, read its man page.
To learn more about man, read its man page:
% man man
It may not be completely obvious how to read a man page, so lets look at an example. The man page for toupper look something like this:
TOUPPER(3) Linux Programmer's Manual TOUPPER(3) NAME toupper, tolower - convert letter to upper or lower case SYNOPSIS #include <ctype.h> int toupper (int c); int tolower (int c); DESCRIPTION toupper() converts the letter c to upper case, if possible. tolower() converts the letter c to lower case, if possible. If c is not an unsigned char value, or EOF, the behaviour of these functions is undefined. RETURN VALUE The value returned is that of the converted letter, or c if the conversion was not possible. CONFORMING TO ANSI C, BSD 4.3 BUGS The details of what constitutes an uppercase or lowercase letter depend on the current locale. For example, the default "C" locale does not know about umlauts, so no con version is done for them. In some non - English locales, there are lowercase letters with no corresponding uppercase equivalent; the German sharp s is one example. SEE ALSO isalpha(3), setlocale(3), locale(7) GNU 1993-04-04 TOUPPER(3)
The first line, TOUPPER(3), tells me that the man page for toupper is in section 3 of the manual.
The NAME, DESCRIPTION, and RETURN VALUE, parts give me short and long versions of what the function does, what its parameter values are, and what it returns.
NAME toupper, tolower - convert letter to upper or lower case DESCRIPTION toupper() converts the letter c to upper case, if possible. RETURN VALUE The value returned is that of the converted letter, or c if the conversion was not possible.The SYNOPSIS part tells me if I need to include any header files to use this and if I need to explicitly link in any libraries, and gives me the full function prototype:
SYNOPSIS #include < ctype.h > int toupper (int c);The SEE ALSO part lists other related functions.
% xmanAnd then choose "Manual Page" button and the "Sections" button from there to choose man pages from the different sections of the manual.
% apropos "current working directory" get_current_dir_name (3) - Get current working directory getcwd (3) - Get current working directory getwd (3) - Get current working directoryThen I can read some of the man pages for the results to see which one of these I want.