update the README

README

@@ -9,147 +9,11 @@ I wrote ccache because I wanted to get a bit more speed out of a
 compiler cache and I wanted to remove some of the limitations of the
 shell-script version.
 
-Installation
+Please see the manual page and documentation at
-------------
+http://ccache.samba.org/
 
-There are two ways to use ccache. You can either prefix your compile
-commands with "ccache" or you can create a symbolic link between
-ccache and the names of your compilers. The first method is most
-convenient if you just want to try out ccache or wish to use it for
-some specific projects. The second method is most useful for when you
-wish to use ccache for all your compiles.
-
-To install for usage by the first method just copy ccache to somewhere
-in your path. 
-
-To install for the second method do something like this:
-
-  cp ccache /usr/local/bin/
-  ln -s /usr/local/bin/ccache /usr/local/bin/gcc
-  ln -s /usr/local/bin/ccache /usr/local/bin/cc
-
-This will work as long as /usr/local/bin comes before the path to gcc
-(which is usually in /usr/bin). After installing you may wish to run
-"which gcc" to make sure that the correct link is being used.
-
-Setting cache limits
---------------------
-
-Run "ccache -h" to see a list of options. The main ones you may wish
-to look at are "ccache -M" and "ccache -F" for setting the cache size
-limits.
-
-You can use "ccache -s" to look at the cache hit/miss statistics.
-
-Configuration
--------------
-
-Configuration of ccache is done via a number of environment variables
-and via ccache commands. In most cases you won't need any of these as
-the defaults will be fine.
-
-   CCACHE_DIR
-
-   the CCACHE_DIR environment variable specifies where ccache will
-   keep its cached compiler output. The default is "$HOME/.ccache". 
-
-
-   CCACHE_LOGFILE
-
-   If you set the CCACHE_LOGFILE environment variable then ccache will
-   write some log information on cache hits and misses in that
-   file. This is useful for tracking down problems.
-
-
-   CCACHE_PATH
-
-   You can optionally set CCACHE_PATH to a colon separated path where ccache will
-   look for the real compilers. If you don't do this then ccache will
-   look for the first executable in the normal PATH that isn't a link
-   to ccache itself.
-
-
-   CCACHE_DISABLE
-
-   If you set the environment variable CCACHE_DISABLE then ccache will
-   just call the real compiler, bypassing the cache completely.
-
-
-Differences
 -----------
 
-The biggest differences between Erik's compilercache script and ccache
-are:
-
-- ccache is written in C, which makes it a bit faster (calling out to
-  external programs is mostly what slowed down the scripts).
-
-- ccache can automatically find the real compiler
-
-- ccache keeps statistics on hits/misses
-
-- ccache can do automatic cache management
-
-- ccache can cache compiler output that includes warnings. In many
-  cases this gives ccache a much higher cache hit rate.
-
-- ccache can handle argument lists with spaces
-
-- compilercache does much smarter token unification using a C
-  lexer. This means that reformatting of source code is much more
-  likely to result in a cache miss with ccache than with
-  compilercache. I may add this in future, although it is perhaps
-  debatable whether the much slower parsing is worth it.
-
-Note however that ccache is a very new piece of code (as of March
-2002) whereas Erik's scripts have had a *lot* more testing. 
-
-The overall speedup compared to compilercache is quite dramatic. For
-compiling rsync I get:
-
-  normal build 20.74 seconds
-
-  compilercache uncached 28.9 seconds
-  compilercache cached 10.5 seconds
-
-  ccache uncached 24.6 seconds
-  ccache cached 4.6 seconds
-
-Cleaning size management
-------------------------
-
-By default ccache has no limit on the cache size. You can set a limit
-using the "ccache -M" and "ccache -F" options, which set the size and
-number of files limits.
-
-When these limits are reached ccache will reduce the cache to 20%
-below the numbers you specified in order to avoid doing the cache
-clean operation too often.
-
-How it works
-------------
-
-The basic idea is to detect when you are compiling exactly the same
-code a 2nd time and use the previously compiled output. You detect
-that it is the same code by forming a hash of:
-
-  - the pre-processor output from running the compiler with -E
-  - the command line options
-  - the real compilers size and modification time
-  - any stderr output generated by the compiler
-
-These are hashed using md4 (a strong hash) and a cache file is formed
-based on that hash result. When the same compilation is done a second
-time ccache is able to supply the correct compiler output (including
-all warnings etc) from the cache.
-
-ccache has been carefully written to always produce exactly the same
-compiler output that you would get without the cache. If you ever
-discover a case where ccache changes the output of your compiler then
-please let me know.
-
-===================
 Andrew Tridgell
 http://samba.org/~tridge/
 bugs@ccache.samba.org
-March 2002