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By far the most comprehensive, yet somewhat obscure source is the online manual. In fact, the entire UNIX Programmer's Manual is stored online. The trick is first learning how to access it, then learning how to read it. The program you use to access the manual is called man. It considers its arguments (whatever else you type on the command line after the command name) to be things you want help on. For example, if you wanted man to tell you about itself, you would type
vega1% man man
This will show the manual page on the man program itself. Be aware that man will only explain something to you if you can ask for it by name. Unfortunately, there are many occasions when you don't know what UNIX calls the program you need to run. You may use apropos to find out what the system knows about some subject. For example,
vega1% apropos compiler
cc (1v) - C compiler error (1) - categorizes compiler error messages, insert at responsible source file names rpcgen (1) - RPC protocol compiler tic (8v) - terminfo compiler yacc (1) - yet another compiler-compiler: parsing program generator zic (8) - time zone compiler acc (1) - ANSI C compiler f77 (1) - Sun FORTRAN compiler rpcgen (1) - RPC protocol compiler sbinit, sbinit (5) - directives to Sun SourceBrowser and compilers yacc++ (1) - yet another compiler-compiler: parsing program generator clccxref (1) - processes one or more CenterLine-C Compiler source files and produces a cross-reference listing on standard output clcp, cpp (1) - The CenterLine-C++ Preprocessor, based on the GNU C-Compatible Compiler Preprocessor. compile\_et (1) - error table compiler cccp, cpp (1) - The GNU C-Compatible Compiler Preprocessor. g++ (1) - GNU project C++ Compiler (v2.4)
apropos shows you all the various subjects that the online manual knows concerning the topic compilers. The words cc, gcc, acc etc., are items that man knows about. The parenthesized number that follows the command name indicates the section of the manual where the topic can be found. You need to know this because often the same topic appears in more than one section of the manual, and you need to be able to specify which section you are interested in. The various sections and their uses are the following:
Sections of Man Pages | |
---|---|
Section | Contents |
1 | Programs(commands) |
2 | System Calls |
3 | Subroutine Libraries |
4 | Hardware |
5 | Configuration Files |
6 | Games |
7 | Miscellaneous |
8 | ySystem Administration |
Sections can also be divided into subsections. These subsections are denoted by one letter, and indicate which library the routine can be found in (c for compatibility, f for Fortran, m for math, etc.) You may notice that topics may appear it more that one place. To distinguish which page you want to see, you precede the name with the section. Some examples are:
vega1% man 8 zic
vega1% man 8v tic
Note that there is an intro page for each section (1, 2, 3, 3f, 3m, etc.) Thus if you would like to know more about math subroutines, type
vega1% man 3m intro
Commands for viewing the man page are much like those for the pager less (press h for a command summary).