make quick reference guide
    
    
    Command flags
    -------------
    -b              Compatibility mode for old makefiles.
    -e              Environment variables override assignments.
    -f <file>       Use <file> for makefile.
    -i              Ignore all errors.
    -k              Keep going even after detecting an error.
    -n              Don't actually execute.
    -p              Print complete set of macro definitions and target
                    descriptions.
    -q              Query and return 0 if up-to-date.
    -r              Remove built-in rules.
    -s              Do not echo commands.
    -t              Just touch targets.
    VAR=value       Set the value of variable VAR.
    
    Makefile Search Order
    ---------------------
    ./makefile
    ./Makefile
    ./s.makefile
    ./s.Makefile
    
    Dependency operators
    --------------------
    :       Set dependency for target to source.  Can accumulate over
            multiple lines.
    
    Preprocess characters
    ---------------------
    -       Ignore errors for this shell line.
    @       Do not print this line.
    
    Variable definitions
    --------------------
    <var> = <value>         Set <var> to <value>.
    
    Predefined local variables
    --------------------------
    $@              Name of the target.
    $?              List of sources that were out of date.
    $*              File portion of the current dependent being processed.
    $<              Implied source file for this target (if none
                    provided).
    $%              The path to an archive file.
    $@F             File portion of target file.
    $<F             File portion of all sources for this target.
    $*F             File portion of current file being processed.
    $%F             File portion of archive file.
    $@D             Directory portion of target file.
    $<D             Directory portion of all sources for this target.
    $*D             Directory portion of the current file being processed.
    $%D             Directory portion of archive file.
    
    Predefined variables
    --------------------
    MAKE            Set to name by which pmake was invoked.
    MAKEFLAGS       Set to flags passed to make as well as options in the
                    environment variable MAKEFLAGS.
    
    Environment variables
    ---------------------
    SHELL           Shell that make should use.
    MAKEFLAGS       Set to flags to be used by make.
    
    Variable expansion
    ------------------
    $(<var>[:<str1>=[<str2>]])      Substitutes <str1> at the end of a
                    word are replaced with <str2>.
    
    Special make commands
    ----------------------
    include <file>          Include <file> from current directory.
    
    Target attributes       <target> : <attribute>
    -----------------
    .DEFAULT        Performed if make can't figure out how to make a
                    particular target.
    .IGNORE         Ignore errors from target's commands.
    .PRECIOUS       Do not delete target if pmake is interrupted.
    .SILENT         Do not echo script.
    .SUFFIXES       Defines the suffixes that make should recognize.
    
    Special targets
    ---------------
    
    Files of interest
    -----------------
    /usr/include/make/commondefs
    /usr/include/make/commonrules
    /usr/include/make/defs