{{{kmk}}} is the {{{make}}} program in [wiki:kBuild kBuild], e.g. it is what you invoke from the commandline or editor to perform the actual build. {{{kmk}}} is based on the latest [wiki:'GNU make'] release, currently 3.81, but provides a bunch of additional features required by the [wiki:kBuild kBuild] makefile scripts.

Why not use vanilla [wiki:'GNU make']? There are several reasons:
 * When [wiki:kBuild kBuild] was reborn using [wiki:'GNU make'] (an earlier incarnation of the project was based on FreeBSD make) the 3.81 release was about 2 years ahead. [wiki:kBuild kBuild] relies on many features introduced after 3.80. Requiring 3.81 to be installed still isn't a viable option.
 * Be able to add new features without having trouble getting them accepted or having to wait 3-4 years until the next [wiki:'GNU make'] version is released and makes it out to all the corners of the world.
 * Be able to fix bugs fast, same reasoning as above.
 * Not having to require a specific, perhaps even unreleased, [wiki:'GNU make'] version.
 * Not having to deal with missing features and bugs specific to various [wiki:'GNU make'] versions and ports.
 * Finally, because we can. :-)

The current {{{kmk}}} code contains the following changes from [wiki:'GNU make']:
 * It has some extra predefined variables: 
   * {{{KMK}}} (similar to {{{MAKE}}})
   * {{{KMK_VERSION}}}
   * {{{KMK_FEATURES}}}
   * {{{KBUILD_VERSION}}}
   * {{{KBUILD_VERSION_MAJOR}}}
   * {{{KBUILD_VERSION_MINOR}}}
   * {{{KBUILD_VERSION_PATCH}}}
   * {{{PATH_KBUILD}}}
   * {{{PATH_KBUILD_BIN}}}
 * It has a few new builtin functions:
   * {{{abspathex}}}
   * {{{compcmds}}}
   * {{{compvar}}}
   * {{{int-add}}}
   * {{{int-sub}}}
   * {{{int-mul}}}
   * {{{int-div}}}
   * {{{int-mod}}}
   * {{{int-not}}}
   * {{{int-and}}}
   * {{{int-or}}}
   * {{{int-xor}}}
   * {{{int-eq}}}
   * {{{int-ne}}}
   * {{{int-gt}}}
   * {{{int-ge}}}
   * {{{int-lt}}}
   * {{{int-le}}}
   * {{{rsort}}}
   * {{{stack-push}}}
   * {{{stack-pop}}}
   * {{{stack-popv}}}
   * {{{stack-top}}}
   * {{{toupper}}}
   * {{{tolower}}}
   * {{{xargs}}}
   * {{{eq}}} ("experimental" GNU make code)
   * {{{not}}} ("experimental" GNU make code)
   * {{{kb-src-tool}}} (kBuild internal)
   * {{{kb-obj-base}}} (kBuild internal)
   * {{{kb-obj-suff}}} (kBuild internal)
   * {{{kb-src-prop}}} (kBuild internal)
   * {{{kb-src-one}}} (kBuild internal)
 * Explicit multi-target rules, e.i. explicit make rules that output more than one file.
 * Prepend assignment operator, {{{<=}}}.
 * It contains bugfixes for several bugs in the Windows and OS/2 ports, most importantly path case mixups, broken shell invocation, and abspath.
 * It has several performance improvements with respect to the kind of work [wiki:kBuild kBuild] puts make thru. Most notably, keeping name and value lengths for variables and thereby skipping a lot of {{{strlen()}}} and being able to use {{{memcpy()}}} instead of {{{strcpy()}}}, and the variable append/prepend optimization ({{{+=}}} and {{{<=}}}). The latter was a major issue with the way [wiki:kBuild kBuild] is scripted.
 * A bunch of builtin utilities which will be invoked without spawning new process or shell. Most of these are taken from BSD.
   * kmk_builtin_append
   * kmk_builtin_cp
   * kmk_builtin_cat
   * kmk_builtin_echo
   * kmk_builtin_install
   * kmk_builtin_ln
   * kmk_builtin_mkdir
   * kmk_builtin_mv
   * kmk_builtin_rm (clean just wouldn't work without this)
   * kmk_builtin_rmdir
   * kmk_builtin_printf
 * A new argument {{{--priority <1..5>}}} which sets the priority of the [wiki:kmk] process. 1 is idle time, 3 is normal, and 5 is highest priority.
 * The special {{{.NOTPARALLEL}}} [wiki:goals goal] has been extended to be able to take a list of [wiki:goals] that must be executed without any parallel building going on. If no list is given, it will work like in vanilla [wiki:'GNU make'] which means the entire makefile will be executed without any parallel building. This extension is required to make the {{{-jN}}} argument useful in [wiki:kBuild].