xref: /freebsd/contrib/bmake/bmake.cat1 (revision d9a42747950146bf03cda7f6e25d219253f8a57a)

BMAKE(1)                FreeBSD General Commands Manual               BMAKE(1)

NAME
     bmake -- maintain program dependencies

SYNOPSIS
     bmake [-BeikNnqrSstWwX] [-C directory] [-D variable] [-d flags]
           [-f makefile] [-I directory] [-J private] [-j max_jobs]
           [-m directory] [-T file] [-V variable] [-v variable]
           [variable=value] [target ...]

DESCRIPTION
     bmake is a program designed to simplify the maintenance of other pro-
     grams.  Its input is a list of specifications as to the files upon which
     programs and other files depend.  If no -f makefile option is given,
     bmake tries to open `makefile' then `Makefile' in order to find the spec-
     ifications.  If the file `.depend' exists, it is read, see mkdep(1).

     This manual page is intended as a reference document only.  For a more
     thorough description of bmake and makefiles, please refer to PMake - A
     Tutorial (from 1993).

     bmake prepends the contents of the MAKEFLAGS environment variable to the
     command line arguments before parsing them.

     The options are as follows:

     -B      Try to be backwards compatible by executing a single shell per
             command and by making the sources of a dependency line in se-
             quence.

     -C directory
             Change to directory before reading the makefiles or doing any-
             thing else.  If multiple -C options are specified, each is inter-
             preted relative to the previous one: -C / -C etc is equivalent to
             -C /etc.

     -D variable
             Define variable to be 1, in the global scope.

     -d [-]flags
             Turn on debugging, and specify which portions of bmake are to
             print debugging information.  Unless the flags are preceded by
             `-', they are added to the MAKEFLAGS environment variable and are
             passed on to any child make processes.  By default, debugging in-
             formation is printed to standard error, but this can be changed
             using the F debugging flag.  The debugging output is always un-
             buffered; in addition, if debugging is enabled but debugging out-
             put is not directed to standard output, the standard output is
             line buffered.  The available flags are:

             A       Print all possible debugging information; equivalent to
                     specifying all of the debugging flags.

             a       Print debugging information about archive searching and
                     caching.

             C       Print debugging information about the current working di-
                     rectory.

             c       Print debugging information about conditional evaluation.

             d       Print debugging information about directory searching and
                     caching.

             e       Print debugging information about failed commands and
                     targets.

             F[+]filename
                     Specify where debugging output is written.  This must be
                     the last flag, because it consumes the remainder of the
                     argument.  If the character immediately after the F flag
                     is `+', the file is opened in append mode; otherwise the
                     file is overwritten.  If the file name is `stdout' or
                     `stderr', debugging output is written to the standard
                     output or standard error output respectively (and the `+'
                     option has no effect).  Otherwise, the output is written
                     to the named file.  If the file name ends with `.%d', the
                     `%d' is replaced by the pid.

             f       Print debugging information about loop evaluation.

             g1      Print the input graph before making anything.

             g2      Print the input graph after making everything, or before
                     exiting on error.

             g3      Print the input graph before exiting on error.

             h       Print debugging information about hash table operations.

             j       Print debugging information about running multiple
                     shells.

             L       Turn on lint checks.  This throws errors for variable as-
                     signments that do not parse correctly, at the time of as-
                     signment, so the file and line number are available.

             l       Print commands in Makefiles regardless of whether or not
                     they are prefixed by `@' or other "quiet" flags.  Also
                     known as "loud" behavior.

             M       Print debugging information about "meta" mode decisions
                     about targets.

             m       Print debugging information about making targets, includ-
                     ing modification dates.

             n       Don't delete the temporary command scripts created when
                     running commands.  These temporary scripts are created in
                     the directory referred to by the TMPDIR environment vari-
                     able, or in /tmp if TMPDIR is unset or set to the empty
                     string.  The temporary scripts are created by mkstemp(3),
                     and have names of the form makeXXXXXX.  NOTE: This can
                     create many files in TMPDIR or /tmp, so use with care.

             p       Print debugging information about makefile parsing.

             s       Print debugging information about suffix-transformation
                     rules.

             t       Print debugging information about target list mainte-
                     nance.

             V       Force the -V option to print raw values of variables,
                     overriding the default behavior set via
                     .MAKE.EXPAND_VARIABLES.

             v       Print debugging information about variable assignment and
                     expansion.

             x       Run shell commands with -x so the actual commands are
                     printed as they are executed.

     -e      Let environment variables override global variables within make-
             files.

     -f makefile
             Specify a makefile to read instead of the default makefile or
             Makefile.  If makefile is `-', standard input is read.  Multiple
             makefiles may be specified, and are read in the order specified.

     -I directory
             Specify a directory in which to search for makefiles and included
             makefiles.  The system makefile directory (or directories, see
             the -m option) is automatically included as part of this list.

     -i      Ignore non-zero exit of shell commands in the makefile.  Equiva-
             lent to specifying `-' before each command line in the makefile.

     -J private
             This option should not be specified by the user.

             When the -j option is in use in a recursive build, this option is
             passed by a make to child makes to allow all the make processes
             in the build to cooperate to avoid overloading the system.

     -j max_jobs
             Specify the maximum number of jobs that bmake may have running at
             any one time.  The value is saved in .MAKE.JOBS.  Turns compati-
             bility mode off, unless the -B option is also specified.  When
             compatibility mode is off, all commands associated with a target
             are executed in a single shell invocation as opposed to the tra-
             ditional one shell invocation per line.  This can break tradi-
             tional scripts which change directories on each command invoca-
             tion and then expect to start with a fresh environment on the
             next line.  It is more efficient to correct the scripts rather
             than turn backwards compatibility on.

     -k      Continue processing after errors are encountered, but only on
             those targets that do not depend on the target whose creation
             caused the error.

     -m directory
             Specify a directory in which to search for sys.mk and makefiles
             included via the <file>-style include statement.  The -m option
             can be used multiple times to form a search path.  This path
             overrides the default system include path /usr/share/mk.  Fur-
             thermore, the system include path is appended to the search path
             used for "file"-style include statements (see the -I option).
             The system include path can be referenced via the read-only vari-
             able .SYSPATH.

             If a directory name in the -m argument (or the MAKESYSPATH envi-
             ronment variable) starts with the string `.../', bmake searches
             for the specified file or directory named in the remaining part
             of the argument string.  The search starts with the current di-
             rectory and then works upward towards the root of the file sys-
             tem.  If the search is successful, the resulting directory re-
             places the `.../' specification in the -m argument.  This feature
             allows bmake to easily search in the current source tree for cus-
             tomized sys.mk files (e.g., by using `.../mk/sys.mk' as an argu-
             ment).

     -n      Display the commands that would have been executed, but do not
             actually execute them unless the target depends on the .MAKE spe-
             cial source (see below) or the command is prefixed with `+'.

     -N      Display the commands that would have been executed, but do not
             actually execute any of them; useful for debugging top-level
             makefiles without descending into subdirectories.

     -q      Do not execute any commands, instead exit 0 if the specified tar-
             gets are up to date, and 1 otherwise.

     -r      Do not use the built-in rules specified in the system makefile.

     -S      Stop processing if an error is encountered.  This is the default
             behavior and the opposite of -k.

     -s      Do not echo any commands as they are executed.  Equivalent to
             specifying `@' before each command line in the makefile.

     -T tracefile
             When used with the -j flag, append a trace record to tracefile
             for each job started and completed.

     -t      Rather than re-building a target as specified in the makefile,
             create it or update its modification time to make it appear up-
             to-date.

     -V variable
             Print the value of variable.  Do not build any targets.  Multiple
             instances of this option may be specified; the variables are
             printed one per line, with a blank line for each null or unde-
             fined variable.  The value printed is extracted from the global
             scope after all makefiles have been read.

             By default, the raw variable contents (which may include addi-
             tional unexpanded variable references) are shown.  If variable
             contains a `$', it is not interpreted as a variable name but
             rather as an expression.  Its value is expanded before printing.
             The value is also expanded before printing if
             .MAKE.EXPAND_VARIABLES is set to true and the -dV option has not
             been used to override it.

             Note that loop-local and target-local variables, as well as val-
             ues taken temporarily by global variables during makefile pro-
             cessing, are not accessible via this option.  The -dv debug mode
             can be used to see these at the cost of generating substantial
             extraneous output.

     -v variable
             Like -V, but all printed variables are always expanded to their
             complete value.  The last occurrence of -V or -v decides whether
             all variables are expanded or not.

     -W      Treat any warnings during makefile parsing as errors.

     -w      Print entering and leaving directory messages, pre and post pro-
             cessing.

     -X      Don't export variables passed on the command line to the environ-
             ment individually.  Variables passed on the command line are
             still exported via the MAKEFLAGS environment variable.  This op-
             tion may be useful on systems which have a small limit on the
             size of command arguments.

     variable=value
             Set the value of the variable variable to value.  Normally, all
             values passed on the command line are also exported to sub-makes
             in the environment.  The -X flag disables this behavior.  Vari-
             able assignments should follow options for POSIX compatibility
             but no ordering is enforced.

     There are several different types of lines in a makefile: dependency
     specifications, shell commands, variable assignments, include statements,
     conditional directives, for loops, other directives, and comments.

     Lines may be continued from one line to the next by ending them with a
     backslash (`\').  The trailing newline character and initial whitespace
     on the following line are compressed into a single space.

FILE DEPENDENCY SPECIFICATIONS
     Dependency lines consist of one or more targets, an operator, and zero or
     more sources.  This creates a relationship where the targets "depend" on
     the sources and are customarily created from them.  A target is consid-
     ered out of date if it does not exist, or if its modification time is
     less than that of any of its sources.  An out-of-date target is re-cre-
     ated, but not until all sources have been examined and themselves re-cre-
     ated as needed.  Three operators may be used:

     :     Many dependency lines may name this target but only one may have
           attached shell commands.  All sources named in all dependency lines
           are considered together, and if needed the attached shell commands
           are run to create or re-create the target.  If bmake is inter-
           rupted, the target is removed.

     !     The same, but the target is always re-created whether or not it is
           out of date.

     ::    Any dependency line may have attached shell commands, but each one
           is handled independently: its sources are considered and the at-
           tached shell commands are run if the target is out of date with re-
           spect to (only) those sources.  Thus, different groups of the at-
           tached shell commands may be run depending on the circumstances.
           Furthermore, unlike :, for dependency lines with no sources, the
           attached shell commands are always run.  Also unlike :, the target
           is not removed if bmake is interrupted.

     All dependency lines mentioning a particular target must use the same op-
     erator.

     Targets and sources may contain the shell wildcard values `?', `*', `[]',
     and `{}'.  The values `?', `*', and `[]' may only be used as part of the
     final component of the target or source, and only match existing files.
     The value `{}' need not necessarily be used to describe existing files.
     Expansion is in directory order, not alphabetically as done in the shell.

SHELL COMMANDS
     Each target may have associated with it one or more lines of shell com-
     mands, normally used to create the target.  Each of the lines in this
     script must be preceded by a tab.  (For historical reasons, spaces are
     not accepted.)  While targets can occur in many dependency lines if de-
     sired, by default only one of these rules may be followed by a creation
     script.  If the `::' operator is used, however, all rules may include
     scripts, and the respective scripts are executed in the order found.

     Each line is treated as a separate shell command, unless the end of line
     is escaped with a backslash `\', in which case that line and the next are
     combined.  If the first characters of the command are any combination of
     `@', `+', or `-', the command is treated specially.

           @       causes the command not to be echoed before it is executed.

           +       causes the command to be executed even when -n is given.
                   This is similar to the effect of the .MAKE special source,
                   except that the effect can be limited to a single line of a
                   script.

           -       in compatibility mode causes any non-zero exit status of
                   the command line to be ignored.

     When bmake is run in jobs mode with -j max_jobs, the entire script for
     the target is fed to a single instance of the shell.  In compatibility
     (non-jobs) mode, each command is run in a separate process.  If the com-
     mand contains any shell meta characters (`#=|^(){};&<>*?[]:$`\\n'), it is
     passed to the shell; otherwise bmake attempts direct execution.  If a
     line starts with `-' and the shell has ErrCtl enabled, failure of the
     command line is ignored as in compatibility mode.  Otherwise `-' affects
     the entire job; the script stops at the first command line that fails,
     but the target is not deemed to have failed.

     Makefiles should be written so that the mode of bmake operation does not
     change their behavior.  For example, any command which uses "cd" or
     "chdir" without the intention of changing the directory for subsequent
     commands should be put in parentheses so it executes in a subshell.  To
     force the use of a single shell, escape the line breaks so as to make the
     whole script one command.  For example:

           avoid-chdir-side-effects:
                   @echo "Building $@ in $$(pwd)"
                   @(cd ${.CURDIR} && ${MAKE} $@)
                   @echo "Back in $$(pwd)"

           ensure-one-shell-regardless-of-mode:
                   @echo "Building $@ in $$(pwd)"; \
                   (cd ${.CURDIR} && ${MAKE} $@); \
                   echo "Back in $$(pwd)"

     Since bmake changes the current working directory to `.OBJDIR' before ex-
     ecuting any targets, each child process starts with that as its current
     working directory.

VARIABLE ASSIGNMENTS
     Variables in make behave much like macros in the C preprocessor.

     Variable assignments have the form `NAME op value', where:

           NAME    is a single-word variable name, consisting, by tradition,
                   of all upper-case letters,

           op      is one of the variable assignment operators described be-
                   low, and

           value   is interpreted according to the variable assignment opera-
                   tor.

     Whitespace around NAME, op and value is discarded.

   Variable assignment operators
     The five operators that assign values to variables are:

     =       Assign the value to the variable.  Any previous value is over-
             written.

     +=      Append the value to the current value of the variable, separating
             them by a single space.

     ?=      Assign the value to the variable if it is not already defined.

     :=      Expand the value, then assign it to the variable.

             NOTE: References to undefined variables are not expanded.  This
             can cause problems when variable modifiers are used.

     !=      Expand the value and pass it to the shell for execution, then as-
             sign the output from the child's standard output to the variable.
             Any newlines in the result are replaced with spaces.

   Expansion of variables
     In most contexts where variables are expanded, `$$' expands to a single
     dollar sign.  In other contexts (most variable modifiers, string literals
     in conditions), `\$' expands to a single dollar sign.

     References to variables have the form ${name[:modifiers]} or
     $(name[:modifiers]).  If the variable name consists of only a single
     character and the expression contains no modifiers, the surrounding curly
     braces or parentheses are not required.  This shorter form is not recom-
     mended.

     If the variable name contains a dollar, the name itself is expanded
     first.  This allows almost arbitrary variable names, however names con-
     taining dollar, braces, parentheses or whitespace are really best
     avoided.

     If the result of expanding a nested variable expression contains a dollar
     sign (`$'), the result is subject to further expansion.

     Variable substitution occurs at four distinct times, depending on where
     the variable is being used.

     1.   Variables in dependency lines are expanded as the line is read.

     2.   Variables in conditionals are expanded individually, but only as far
          as necessary to determine the result of the conditional.

     3.   Variables in shell commands are expanded when the shell command is
          executed.

     4.   .for loop index variables are expanded on each loop iteration.  Note
          that other variables are not expanded when composing the body of a
          loop, so the following example code:

                .for i in 1 2 3
                a+=     ${i}
                j=      ${i}
                b+=     ${j}
                .endfor

                all:
                        @echo ${a}
                        @echo ${b}

          prints:

                1 2 3
                3 3 3

          After the loop is executed:

                a       contains `${:U1} ${:U2} ${:U3}', which expands to `1 2
                        3'.

                j       contains `${:U3}', which expands to `3'.

                b       contains `${j} ${j} ${j}', which expands to `${:U3}
                        ${:U3} ${:U3}' and further to `3 3 3'.

   Variable classes
     The four different classes of variables (in order of increasing prece-
     dence) are:

     Environment variables
             Variables defined as part of bmake's environment.

     Global variables
             Variables defined in the makefile or in included makefiles.

     Command line variables
             Variables defined as part of the command line.

     Local variables
             Variables that are defined specific to a certain target.

     Local variables can be set on a dependency line, unless
     .MAKE.TARGET_LOCAL_VARIABLES is set to `false'.  The rest of the line
     (which already has had global variables expanded) is the variable value.
     For example:

           COMPILER_WRAPPERS= ccache distcc icecc

           ${OBJS}: .MAKE.META.CMP_FILTER=${COMPILER_WRAPPERS:S,^,N,}

     Only the targets `${OBJS}' are impacted by that filter (in "meta" mode)
     and simply enabling/disabling any of the compiler wrappers does not ren-
     der all of those targets out-of-date.

     NOTE: target-local variable assignments behave differently in that;

           +=      Only appends to a previous local assignment for the same
                   target and variable.

           :=      Is redundant with respect to global variables, which have
                   already been expanded.

     The seven built-in local variables are:

           .ALLSRC   The list of all sources for this target; also known as
                     `>'.

           .ARCHIVE  The name of the archive file; also known as `!'.

           .IMPSRC   In suffix-transformation rules, the name/path of the
                     source from which the target is to be transformed (the
                     "implied" source); also known as `<'.  It is not defined
                     in explicit rules.

           .MEMBER   The name of the archive member; also known as `%'.

           .OODATE   The list of sources for this target that were deemed out-
                     of-date; also known as `?'.

           .PREFIX   The file prefix of the target, containing only the file
                     portion, no suffix or preceding directory components;
                     also known as `*'.  The suffix must be one of the known
                     suffixes declared with .SUFFIXES, or it is not recog-
                     nized.

           .TARGET   The name of the target; also known as `@'.  For compati-
                     bility with other makes this is an alias for .ARCHIVE in
                     archive member rules.

     The shorter forms (`>', `!', `<', `%', `?', `*', and `@') are permitted
     for backward compatibility with historical makefiles and legacy POSIX
     make and are not recommended.

     Variants of these variables with the punctuation followed immediately by
     `D' or `F', e.g. `$(@D)', are legacy forms equivalent to using the `:H'
     and `:T' modifiers.  These forms are accepted for compatibility with AT&T
     System V UNIX makefiles and POSIX but are not recommended.

     Four of the local variables may be used in sources on dependency lines
     because they expand to the proper value for each target on the line.
     These variables are `.TARGET', `.PREFIX', `.ARCHIVE', and `.MEMBER'.

   Additional built-in variables
     In addition, bmake sets or knows about the following variables:

     .ALLTARGETS
             The list of all targets encountered in the makefiles.  If evalu-
             ated during makefile parsing, lists only those targets encoun-
             tered thus far.

     .CURDIR
             A path to the directory where bmake was executed.  Refer to the
             description of `PWD' for more details.

     .ERROR_CMD
             Is used in error handling, see MAKE_PRINT_VAR_ON_ERROR.

     .ERROR_CWD
             Is used in error handling, see MAKE_PRINT_VAR_ON_ERROR.

     .ERROR_META_FILE
             Is used in error handling in "meta" mode, see
             MAKE_PRINT_VAR_ON_ERROR.

     .ERROR_TARGET
             Is used in error handling, see MAKE_PRINT_VAR_ON_ERROR.

     .INCLUDEDFROMDIR
             The directory of the file this makefile was included from.

     .INCLUDEDFROMFILE
             The filename of the file this makefile was included from.

     MACHINE
             The machine hardware name, see uname(1).

     MACHINE_ARCH
             The machine processor architecture name, see uname(1).

     MAKE    The name that bmake was executed with (argv[0]).

     .MAKE   The same as MAKE, for compatibility.  The preferred variable to
             use is the environment variable MAKE because it is more compati-
             ble with other make variants and cannot be confused with the spe-
             cial target with the same name.

     .MAKE.DEPENDFILE
             Names the makefile (default `.depend') from which generated de-
             pendencies are read.

     .MAKE.DIE_QUIETLY
             If set to `true', do not print error information at the end.

     .MAKE.EXPAND_VARIABLES
             A boolean that controls the default behavior of the -V option.
             If true, variable values printed with -V are fully expanded; if
             false, the raw variable contents (which may include additional
             unexpanded variable references) are shown.

     .MAKE.EXPORTED
             The list of variables exported by bmake.

     MAKEFILE
             The top-level makefile that is currently read, as given in the
             command line.

     .MAKEFLAGS
             The environment variable `MAKEFLAGS' may contain anything that
             may be specified on bmake's command line.  Anything specified on
             bmake's command line is appended to the .MAKEFLAGS variable,
             which is then added to the environment for all programs that
             bmake executes.

     .MAKE.GID
             The numeric group ID of the user running bmake.  It is read-only.

     .MAKE.JOB.PREFIX
             If bmake is run with -j, the output for each target is prefixed
             with a token
                   --- target ---
             the first part of which can be controlled via .MAKE.JOB.PREFIX.
             If .MAKE.JOB.PREFIX is empty, no token is printed.  For example,
             setting .MAKE.JOB.PREFIX to
             `${.newline}---${.MAKE:T}[${.MAKE.PID}]' would produce tokens
             like
                   ---make[1234] target ---
             making it easier to track the degree of parallelism being
             achieved.

     .MAKE.JOBS
             The argument to the -j option.

     .MAKE.LEVEL
             The recursion depth of bmake.  The top-level instance of bmake
             has level 0, and each child make has its parent level plus 1.
             This allows tests like: .if ${.MAKE.LEVEL} == 0 to protect things
             which should only be evaluated in the top-level instance of
             bmake.

     .MAKE.LEVEL.ENV
             The name of the environment variable that stores the level of
             nested calls to bmake.

     .MAKE.MAKEFILE_PREFERENCE
             The ordered list of makefile names (default `makefile',
             `Makefile') that bmake looks for.

     .MAKE.MAKEFILES
             The list of makefiles read by bmake, which is useful for tracking
             dependencies.  Each makefile is recorded only once, regardless of
             the number of times read.

     .MAKE.META.BAILIWICK
             In "meta" mode, provides a list of prefixes which match the di-
             rectories controlled by bmake.  If a file that was generated out-
             side of .OBJDIR but within said bailiwick is missing, the current
             target is considered out-of-date.

     .MAKE.META.CMP_FILTER
             In "meta" mode, it can (very rarely!) be useful to filter command
             lines before comparison.  This variable can be set to a set of
             modifiers that are applied to each line of the old and new com-
             mand that differ, if the filtered commands still differ, the tar-
             get is considered out-of-date.

     .MAKE.META.CREATED
             In "meta" mode, this variable contains a list of all the meta
             files updated.  If not empty, it can be used to trigger process-
             ing of .MAKE.META.FILES.

     .MAKE.META.FILES
             In "meta" mode, this variable contains a list of all the meta
             files used (updated or not).  This list can be used to process
             the meta files to extract dependency information.

     .MAKE.META.IGNORE_FILTER
             Provides a list of variable modifiers to apply to each pathname.
             Ignore if the expansion is an empty string.

     .MAKE.META.IGNORE_PATHS
             Provides a list of path prefixes that should be ignored; because
             the contents are expected to change over time.  The default list
             includes: `/dev /etc /proc /tmp /var/run /var/tmp'

     .MAKE.META.IGNORE_PATTERNS
             Provides a list of patterns to match against pathnames.  Ignore
             any that match.

     .MAKE.META.PREFIX
             Defines the message printed for each meta file updated in "meta
             verbose" mode.  The default value is:
                   Building ${.TARGET:H:tA}/${.TARGET:T}

     .MAKE.MODE
             Processed after reading all makefiles.  Affects the mode that
             bmake runs in.  It can contain these keywords:

             compat  Like -B, puts bmake into "compat" mode.

             meta    Puts bmake into "meta" mode, where meta files are created
                     for each target to capture the command run, the output
                     generated, and if filemon(4) is available, the system
                     calls which are of interest to bmake.  The captured out-
                     put can be useful when diagnosing errors.

             curdirOk=bf
                     By default, bmake does not create .meta files in
                     `.CURDIR'.  This can be overridden by setting bf to a
                     value which represents true.

             missing-meta=bf
                     If bf is true, a missing .meta file makes the target out-
                     of-date.

             missing-filemon=bf
                     If bf is true, missing filemon data makes the target out-
                     of-date.

             nofilemon
                     Do not use filemon(4).

             env     For debugging, it can be useful to include the environ-
                     ment in the .meta file.

             verbose
                     If in "meta" mode, print a clue about the target being
                     built.  This is useful if the build is otherwise running
                     silently.  The message printed is the expanded value of
                     .MAKE.META.PREFIX.

             ignore-cmd
                     Some makefiles have commands which are simply not stable.
                     This keyword causes them to be ignored for determining
                     whether a target is out of date in "meta" mode.  See also
                     .NOMETA_CMP.

             silent=bf
                     If bf is true, when a .meta file is created, mark the
                     target .SILENT.

             randomize-targets
                     In both compat and parallel mode, do not make the targets
                     in the usual order, but instead randomize their order.
                     This mode can be used to detect undeclared dependencies
                     between files.

     MAKEOBJDIR
             Used to create files in a separate directory, see .OBJDIR.

     MAKE_OBJDIR_CHECK_WRITABLE
             Used to force a separate directory for the created files, even if
             that directory is not writable, see .OBJDIR.

     MAKEOBJDIRPREFIX
             Used to create files in a separate directory, see .OBJDIR.

     .MAKE.OS
             The name of the operating system, see uname(1).  It is read-only.

     .MAKEOVERRIDES
             This variable is used to record the names of variables assigned
             to on the command line, so that they may be exported as part of
             `MAKEFLAGS'.  This behavior can be disabled by assigning an empty
             value to `.MAKEOVERRIDES' within a makefile.  Extra variables can
             be exported from a makefile by appending their names to
             `.MAKEOVERRIDES'.  `MAKEFLAGS' is re-exported whenever
             `.MAKEOVERRIDES' is modified.

     .MAKE.PATH_FILEMON
             If bmake was built with filemon(4) support, this is set to the
             path of the device node.  This allows makefiles to test for this
             support.

     .MAKE.PID
             The process ID of bmake.  It is read-only.

     .MAKE.PPID
             The parent process ID of bmake.  It is read-only.

     MAKE_PRINT_VAR_ON_ERROR
             When bmake stops due to an error, it sets `.ERROR_TARGET' to the
             name of the target that failed, `.ERROR_CMD' to the commands of
             the failed target, and in "meta" mode, it also sets `.ERROR_CWD'
             to the getcwd(3), and `.ERROR_META_FILE' to the path of the meta
             file (if any) describing the failed target.  It then prints its
             name and the value of `.CURDIR' as well as the value of any vari-
             ables named in `MAKE_PRINT_VAR_ON_ERROR'.

     .MAKE.SAVE_DOLLARS
             If true, `$$' are preserved when doing `:=' assignments.  The de-
             fault is false, for backwards compatibility.  Set to true for
             compatability with other makes.  If set to false, `$$' becomes
             `$' per normal evaluation rules.

     .MAKE.TARGET_LOCAL_VARIABLES
             If set to `false', apparent variable assignments in dependency
             lines are treated as normal sources.

     .MAKE.UID
             The numeric ID of the user running bmake.  It is read-only.

     .newline
             This variable is simply assigned a newline character as its
             value.  It is read-only.  This allows expansions using the :@
             modifier to put a newline between iterations of the loop rather
             than a space.  For example, in case of an error, bmake prints the
             variable names and their values using:
                   ${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}

     .OBJDIR
             A path to the directory where the targets are built.  Its value
             is determined by trying to chdir(2) to the following directories
             in order and using the first match:

             1.   ${MAKEOBJDIRPREFIX}${.CURDIR}

                  (Only if `MAKEOBJDIRPREFIX' is set in the environment or on
                  the command line.)

             2.   ${MAKEOBJDIR}

                  (Only if `MAKEOBJDIR' is set in the environment or on the
                  command line.)

             3.   ${.CURDIR}/obj.${MACHINE}

             4.   ${.CURDIR}/obj

             5.   /usr/obj/${.CURDIR}

             6.   ${.CURDIR}

             Variable expansion is performed on the value before it is used,
             so expressions such as ${.CURDIR:S,^/usr/src,/var/obj,} may be
             used.  This is especially useful with `MAKEOBJDIR'.

             `.OBJDIR' may be modified in the makefile via the special target
             `.OBJDIR'.  In all cases, bmake changes to the specified direc-
             tory if it exists, and sets `.OBJDIR' and `PWD' to that directory
             before executing any targets.

             Except in the case of an explicit `.OBJDIR' target, bmake checks
             that the specified directory is writable and ignores it if not.
             This check can be skipped by setting the environment variable
             `MAKE_OBJDIR_CHECK_WRITABLE' to "no".

     .PARSEDIR
             The directory name of the current makefile being parsed.

     .PARSEFILE
             The basename of the current makefile being parsed.  This variable
             and `.PARSEDIR' are both set only while the makefiles are being
             parsed.  To retain their current values, assign them to a vari-
             able using assignment with expansion `:='.

     .PATH   The space-separated list of directories that bmake searches for
             files.  To update this search list, use the special target
             `.PATH' rather than modifying the variable directly.

     %POSIX  Is set in POSIX mode, see the special `.POSIX' target.

     PWD     Alternate path to the current directory.  bmake normally sets
             `.CURDIR' to the canonical path given by getcwd(3).  However, if
             the environment variable `PWD' is set and gives a path to the
             current directory, bmake sets `.CURDIR' to the value of `PWD' in-
             stead.  This behavior is disabled if `MAKEOBJDIRPREFIX' is set or
             `MAKEOBJDIR' contains a variable transform.  `PWD' is set to the
             value of `.OBJDIR' for all programs which bmake executes.

     .SHELL  The pathname of the shell used to run target scripts.  It is
             read-only.

     .SUFFIXES
             The list of known suffixes.  It is read-only.

     .SYSPATH
             The space-separated list of directories that bmake searches for
             makefiles, referred to as the system include path.  To update
             this search list, use the special target `.SYSPATH' rather than
             modifying the variable which is read-only.

     .TARGETS
             The list of targets explicitly specified on the command line, if
             any.

     VPATH   The colon-separated (":") list of directories that bmake searches
             for files.  This variable is supported for compatibility with old
             make programs only, use `.PATH' instead.

   Variable modifiers
     The general format of a variable expansion is:

           ${variable[:modifier[:...]]}

     Each modifier begins with a colon.  To escape a colon, precede it with a
     backslash `\'.

     A list of indirect modifiers can be specified via a variable, as follows:

           modifier_variable = modifier[:...]

           ${variable:${modifier_variable}[:...]}

     In this case, the first modifier in the modifier_variable does not start
     with a colon, since that colon already occurs in the referencing vari-
     able.  If any of the modifiers in the modifier_variable contains a dollar
     sign (`$'), these must be doubled to avoid early expansion.

     Some modifiers interpret the expression value as a single string, others
     treat the expression value as a whitespace-separated list of words.  When
     splitting a string into words, whitespace can be escaped using double
     quotes, single quotes and backslashes, like in the shell.  The quotes and
     backslashes are retained in the words.

     The supported modifiers are:

     :E   Replaces each word with its suffix.

     :H   Replaces each word with its dirname.

     :Mpattern
          Selects only those words that match pattern.  The standard shell
          wildcard characters (`*', `?', and `[]') may be used.  The wildcard
          characters may be escaped with a backslash (`\').  As a consequence
          of the way values are split into words, matched, and then joined,
          the construct `${VAR:M*}' removes all leading and trailing white-
          space and normalizes the inter-word spacing to a single space.

     :Npattern
          This is the opposite of `:M', selecting all words which do not match
          pattern.

     :O   Orders the words lexicographically.

     :On  Orders the words numerically.  A number followed by one of `k', `M'
          or `G' is multiplied by the appropriate factor, which is 1024 for
          `k', 1048576 for `M', or 1073741824 for `G'.  Both upper- and lower-
          case letters are accepted.

     :Or  Orders the words in reverse lexicographical order.

     :Orn
          Orders the words in reverse numerical order.

     :Ox  Shuffles the words.  The results are different each time you are re-
          ferring to the modified variable; use the assignment with expansion
          `:=' to prevent such behavior.  For example,

                LIST=                   uno due tre quattro
                RANDOM_LIST=            ${LIST:Ox}
                STATIC_RANDOM_LIST:=    ${LIST:Ox}

                all:
                        @echo "${RANDOM_LIST}"
                        @echo "${RANDOM_LIST}"
                        @echo "${STATIC_RANDOM_LIST}"
                        @echo "${STATIC_RANDOM_LIST}"
          may produce output similar to:

                quattro due tre uno
                tre due quattro uno
                due uno quattro tre
                due uno quattro tre

     :Q   Quotes every shell meta-character in the value, so that it can be
          passed safely to the shell.

     :q   Quotes every shell meta-character in the value, and also doubles `$'
          characters so that it can be passed safely through recursive invoca-
          tions of bmake.  This is equivalent to `:S/\$/&&/g:Q'.

     :R   Replaces each word with everything but its suffix.

     :range[=count]
          The value is an integer sequence representing the words of the orig-
          inal value, or the supplied count.

     :gmtime[=timestamp]
          The value is interpreted as a format string for strftime(3), using
          gmtime(3), producing the formatted timestamp.  If a timestamp value
          is not provided or is 0, the current time is used.

     :hash
          Computes a 32-bit hash of the value and encodes it as 8 hex digits.

     :localtime[=timestamp]
          The value is interpreted as a format string for strftime(3), using
          localtime(3), producing the formatted timestamp.  If a timestamp
          value is not provided or is 0, the current time is used.

     :tA  Attempts to convert the value to an absolute path using realpath(3).
          If that fails, the value is unchanged.

     :tl  Converts the value to lower-case letters.

     :tsc
          When joining the words after a modifier that treats the value as
          words, the words are normally separated by a space.  This modifier
          changes the separator to the character c.  If c is omitted, no sepa-
          rator is used.  The common escapes (including octal numeric codes)
          work as expected.

     :tu  Converts the value to upper-case letters.

     :tW  Causes subsequent modifiers to treat the value as a single word
          (possibly containing embedded whitespace).  See also `:[*]'.

     :tw  Causes the value to be treated as a list of words.  See also `:[@]'.

     :S/old_string/new_string/[1gW]
          Modifies the first occurrence of old_string in each word of the
          value, replacing it with new_string.  If a `g' is appended to the
          last delimiter of the pattern, all occurrences in each word are re-
          placed.  If a `1' is appended to the last delimiter of the pattern,
          only the first occurrence is affected.  If a `W' is appended to the
          last delimiter of the pattern, the value is treated as a single
          word.  If old_string begins with a caret (`^'), old_string is an-
          chored at the beginning of each word.  If old_string ends with a
          dollar sign (`$'), it is anchored at the end of each word.  Inside
          new_string, an ampersand (`&') is replaced by old_string (without
          the anchoring `^' or `$').  Any character may be used as the delim-
          iter for the parts of the modifier string.  The anchoring, ampersand
          and delimiter characters can be escaped with a backslash (`\').

          Both old_string and new_string may contain nested expressions.  To
          prevent a dollar sign from starting a nested expression, escape it
          with a backslash.

     :C/pattern/replacement/[1gW]
          The :C modifier works like the :S modifier except that the old and
          new strings, instead of being simple strings, are an extended regu-
          lar expression pattern (see regex(3)) and an ed(1)-style
          replacement.  Normally, the first occurrence of the pattern pattern
          in each word of the value is substituted with replacement.  The `1'
          modifier causes the substitution to apply to at most one word; the
          `g' modifier causes the substitution to apply to as many instances
          of the search pattern pattern as occur in the word or words it is
          found in; the `W' modifier causes the value to be treated as a sin-
          gle word (possibly containing embedded whitespace).

          As for the :S modifier, the pattern and replacement are subjected to
          variable expansion before being parsed as regular expressions.

     :T   Replaces each word with its last path component (basename).

     :u   Removes adjacent duplicate words (like uniq(1)).

     :?true_string:false_string
          If the variable name (not its value), when parsed as a .if condi-
          tional expression, evaluates to true, return as its value the
          true_string, otherwise return the false_string.  Since the variable
          name is used as the expression, :? must be the first modifier after
          the variable name itself--which, of course, usually contains vari-
          able expansions.  A common error is trying to use expressions like
                ${NUMBERS:M42:?match:no}
          which actually tests defined(NUMBERS).  To determine if any words
          match "42", you need to use something like:
                ${"${NUMBERS:M42}" != "":?match:no}.

     :old_string=new_string
          This is the AT&T System V UNIX style substitution.  It can only be
          the last modifier specified, as a `:' in either old_string or
          new_string is treated as a regular character, not as the end of the
          modifier.

          If old_string does not contain the pattern matching character `%',
          and the word ends with old_string or equals it, that suffix is re-
          placed with new_string.

          Otherwise, the first `%' in old_string matches a possibly empty sub-
          string of arbitrary characters, and if the whole pattern is found in
          the word, the matching part is replaced with new_string, and the
          first occurrence of `%' in new_string (if any) is replaced with the
          substring matched by the `%'.

          Both old_string and new_string may contain nested expressions.  To
          prevent a dollar sign from starting a nested expression, escape it
          with a backslash.

     :@varname@string@
          This is the loop expansion mechanism from the OSF Development Envi-
          ronment (ODE) make.  Unlike .for loops, expansion occurs at the time
          of reference.  For each word in the value, assign the word to the
          variable named varname and evaluate string.  The ODE convention is
          that varname should start and end with a period, for example:
                ${LINKS:@.LINK.@${LN} ${TARGET} ${.LINK.}@}

          However, a single-letter variable is often more readable:
                ${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}

     :_[=var]
          Saves the current variable value in `$_' or the named var for later
          reference.  Example usage:

                M_cmpv.units = 1 1000 1000000
                M_cmpv = S,., ,g:_:range:@i@+ $${_:[-$$i]} \
                \* $${M_cmpv.units:[$$i]}@:S,^,expr 0 ,1:sh

                .if ${VERSION:${M_cmpv}} < ${3.1.12:L:${M_cmpv}}

          Here `$_' is used to save the result of the `:S' modifier which is
          later referenced using the index values from `:range'.

     :Unewval
          If the variable is undefined, newval is the value.  If the variable
          is defined, the existing value is returned.  This is another ODE
          make feature.  It is handy for setting per-target CFLAGS for in-
          stance:
                ${_${.TARGET:T}_CFLAGS:U${DEF_CFLAGS}}
          If a value is only required if the variable is undefined, use:
                ${VAR:D:Unewval}

     :Dnewval
          If the variable is defined, newval is the value.

     :L   The name of the variable is the value.

     :P   The path of the node which has the same name as the variable is the
          value.  If no such node exists or its path is null, the name of the
          variable is used.  In order for this modifier to work, the name
          (node) must at least have appeared on the right-hand side of a de-
          pendency.

     :!cmd!
          The output of running cmd is the value.

     :sh  The value is run as a command, and the output becomes the new value.

     ::=str
          The variable is assigned the value str after substitution.  This
          modifier and its variations are useful in obscure situations such as
          wanting to set a variable at a point where a target's shell commands
          are being parsed.  These assignment modifiers always expand to noth-
          ing.

          The `::' helps avoid false matches with the AT&T System V UNIX style
          `:=' modifier and since substitution always occurs, the `::=' form
          is vaguely appropriate.

     ::?=str
          As for ::= but only if the variable does not already have a value.

     ::+=str
          Append str to the variable.

     ::!=cmd
          Assign the output of cmd to the variable.

     :[range]
          Selects one or more words from the value, or performs other opera-
          tions related to the way in which the value is split into words.

          An empty value, or a value that consists entirely of white-space, is
          treated as a single word.  For the purposes of the `:[]' modifier,
          the words are indexed both forwards using positive integers (where
          index 1 represents the first word), and backwards using negative in-
          tegers (where index -1 represents the last word).

          The range is subjected to variable expansion, and the expanded re-
          sult is then interpreted as follows:

          index  Selects a single word from the value.

          start..end
                 Selects all words from start to end, inclusive.  For example,
                 `:[2..-1]' selects all words from the second word to the last
                 word.  If start is greater than end, the words are output in
                 reverse order.  For example, `:[-1..1]' selects all the words
                 from last to first.  If the list is already ordered, this ef-
                 fectively reverses the list, but it is more efficient to use
                 `:Or' instead of `:O:[-1..1]'.

          *      Causes subsequent modifiers to treat the value as a single
                 word (possibly containing embedded whitespace).  Analogous to
                 the effect of $* in Bourne shell.

          0      Means the same as `:[*]'.

          @      Causes subsequent modifiers to treat the value as a sequence
                 of words delimited by whitespace.  Analogous to the effect of
                 $@ in Bourne shell.

          #      Returns the number of words in the value.

DIRECTIVES
     bmake offers directives for including makefiles, conditionals and for
     loops.  All these directives are identified by a line beginning with a
     single dot (`.') character, followed by the keyword of the directive,
     such as include or if.

   File inclusion
     Files are included with either .include <file> or .include "file".  Vari-
     ables between the angle brackets or double quotes are expanded to form
     the file name.  If angle brackets are used, the included makefile is ex-
     pected to be in the system makefile directory.  If double quotes are
     used, the including makefile's directory and any directories specified
     using the -I option are searched before the system makefile directory.

     For compatibility with other make variants, `include file ...' (without
     leading dot) is also accepted.

     If the include statement is written as .-include or as .sinclude, errors
     locating and/or opening include files are ignored.

     If the include statement is written as .dinclude, not only are errors lo-
     cating and/or opening include files ignored, but stale dependencies
     within the included file are ignored just like in .MAKE.DEPENDFILE.

   Exporting variables
     The directives for exporting and unexporting variables are:

     .export variable ...
             Export the specified global variable.  If no variable list is
             provided, all globals are exported except for internal variables
             (those that start with `.').  This is not affected by the -X
             flag, so should be used with caution.  For compatibility with
             other make programs, export variable=value (without leading dot)
             is also accepted.

             Appending a variable name to .MAKE.EXPORTED is equivalent to ex-
             porting a variable.

     .export-env variable ...
             The same as `.export', except that the variable is not appended
             to .MAKE.EXPORTED.  This allows exporting a value to the environ-
             ment which is different from that used by bmake internally.

     .export-literal variable ...
             The same as `.export-env', except that variables in the value are
             not expanded.

     .unexport variable ...
             The opposite of `.export'.  The specified global variable is re-
             moved from .MAKE.EXPORTED.  If no variable list is provided, all
             globals are unexported, and .MAKE.EXPORTED deleted.

     .unexport-env
             Unexport all globals previously exported and clear the environ-
             ment inherited from the parent.  This operation causes a memory
             leak of the original environment, so should be used sparingly.
             Testing for .MAKE.LEVEL being 0 would make sense.  Also note that
             any variables which originated in the parent environment should
             be explicitly preserved if desired.  For example:

                   .if ${.MAKE.LEVEL} == 0
                   PATH := ${PATH}
                   .unexport-env
                   .export PATH
                   .endif

             Would result in an environment containing only `PATH', which is
             the minimal useful environment.  Actually `.MAKE.LEVEL' is also
             pushed into the new environment.

   Messages
     The directives for printing messages to the output are:

     .info message
             The message is printed along with the name of the makefile and
             line number.

     .warning message
             The message prefixed by `warning:' is printed along with the name
             of the makefile and line number.

     .error message
             The message is printed along with the name of the makefile and
             line number, bmake exits immediately.

   Conditionals
     The directives for conditionals are:

     .if [!]expression [operator expression ...]
             Test the value of an expression.

     .ifdef [!]variable [operator variable ...]
             Test whether a variable is defined.

     .ifndef [!]variable [operator variable ...]
             Test whether a variable is not defined.

     .ifmake [!]target [operator target ...]
             Test the target being requested.

     .ifnmake [!]target [operator target ...]
             Test the target being requested.

     .else   Reverse the sense of the last conditional.

     .elif [!]expression [operator expression ...]
             A combination of `.else' followed by `.if'.

     .elifdef [!]variable [operator variable ...]
             A combination of `.else' followed by `.ifdef'.

     .elifndef [!]variable [operator variable ...]
             A combination of `.else' followed by `.ifndef'.

     .elifmake [!]target [operator target ...]
             A combination of `.else' followed by `.ifmake'.

     .elifnmake [!]target [operator target ...]
             A combination of `.else' followed by `.ifnmake'.

     .endif  End the body of the conditional.

     The operator may be any one of the following:

     ||      Logical OR.

     &&      Logical AND; of higher precedence than `||'.

     bmake only evaluates a conditional as far as is necessary to determine
     its value.  Parentheses can be used to override the operator precedence.
     The boolean operator `!' may be used to logically negate an entire condi-
     tional.  It is of higher precedence than `&&'.

     The value of expression may be any of the following function call expres-
     sions:

     defined(varname)
             Evaluates to true if the variable varname has been defined.

     make(target)
             Evaluates to true if the target was specified as part of bmake's
             command line or was declared the default target (either implic-
             itly or explicitly, see .MAIN) before the line containing the
             conditional.

     empty(varname[:modifiers])
             Evaluates to true if the expansion of the variable, after apply-
             ing the modifiers, results in an empty string.

     exists(pathname)
             Evaluates to true if the given pathname exists.  If relative, the
             pathname is searched for on the system search path (see .PATH).

     target(target)
             Evaluates to true if the target has been defined.

     commands(target)
             Evaluates to true if the target has been defined and has commands
             associated with it.

     Expression may also be an arithmetic or string comparison.  Variable ex-
     pansion is performed on both sides of the comparison.  If both sides are
     numeric and neither is enclosed in quotes, the comparison is done numeri-
     cally, otherwise lexicographically.  A string is interpreted as hexadeci-
     mal integer if it is preceded by 0x, otherwise it is a decimal floating-
     point number; octal numbers are not supported.

     All comparisons may use the operators `==' and `!='.  Numeric comparisons
     may also use the operators `<', `<=', `>' and `>='.

     If the comparison has neither a comparison operator nor a right side, the
     expression evaluates to true if it is nonempty and its numeric value (if
     any) is not zero.

     When bmake is evaluating one of these conditional expressions, and it en-
     counters a (whitespace separated) word it doesn't recognize, either the
     "make" or "defined" function is applied to it, depending on the form of
     the conditional.  If the form is `.ifdef', `.ifndef' or `.if', the
     "defined" function is applied.  Similarly, if the form is `.ifmake' or
     `.ifnmake', the "make" function is applied.

     If the conditional evaluates to true, parsing of the makefile continues
     as before.  If it evaluates to false, the following lines are skipped.
     In both cases, this continues until the corresponding `.else' or `.endif'
     is found.

   For loops
     For loops are typically used to apply a set of rules to a list of files.
     The syntax of a for loop is:

     .for variable [variable ...] in expression
     <make-lines>
     .endfor

     The expression is expanded and then split into words.  On each iteration
     of the loop, one word is taken and assigned to each variable, in order,
     and these variables are substituted into the make-lines inside the body
     of the for loop.  The number of words must come out even; that is, if
     there are three iteration variables, the number of words provided must be
     a multiple of three.

     If `.break' is encountered within a .for loop, it causes early termina-
     tion of the loop, otherwise a parse error.

   Other directives
     .undef variable ...
             Un-define the specified global variables.  Only global variables
             can be un-defined.

COMMENTS
     Comments begin with a hash (`#') character, anywhere but in a shell com-
     mand line, and continue to the end of an unescaped new line.

SPECIAL SOURCES (ATTRIBUTES)
     .EXEC     Target is never out of date, but always execute commands any-
               way.

     .IGNORE   Ignore any errors from the commands associated with this tar-
               get, exactly as if they all were preceded by a dash (`-').

     .MADE     Mark all sources of this target as being up to date.

     .MAKE     Execute the commands associated with this target even if the -n
               or -t options were specified.  Normally used to mark recursive
               bmakes.

     .META     Create a meta file for the target, even if it is flagged as
               .PHONY, .MAKE, or .SPECIAL.  Usage in conjunction with .MAKE is
               the most likely case.  In "meta" mode, the target is out-of-
               date if the meta file is missing.

     .NOMETA   Do not create a meta file for the target.  Meta files are also
               not created for .PHONY, .MAKE, or .SPECIAL targets.

     .NOMETA_CMP
               Ignore differences in commands when deciding if target is out
               of date.  This is useful if the command contains a value which
               always changes.  If the number of commands change, though, the
               target is still considered out of date.  The same effect ap-
               plies to any command line that uses the variable .OODATE, which
               can be used for that purpose even when not otherwise needed or
               desired:


                     skip-compare-for-some:
                             @echo this is compared
                             @echo this is not ${.OODATE:M.NOMETA_CMP}
                             @echo this is also compared

               The :M pattern suppresses any expansion of the unwanted vari-
               able.

     .NOPATH   Do not search for the target in the directories specified by
               .PATH.

     .NOTMAIN  Normally bmake selects the first target it encounters as the
               default target to be built if no target was specified.  This
               source prevents this target from being selected.

     .OPTIONAL
               If a target is marked with this attribute and bmake can't fig-
               ure out how to create it, it ignores this fact and assumes the
               file isn't needed or already exists.

     .PHONY    The target does not correspond to an actual file; it is always
               considered to be out of date, and is not created with the -t
               option.  Suffix-transformation rules are not applied to .PHONY
               targets.

     .PRECIOUS
               When bmake is interrupted, it normally removes any partially
               made targets.  This source prevents the target from being re-
               moved.

     .RECURSIVE
               Synonym for .MAKE.

     .SILENT   Do not echo any of the commands associated with this target,
               exactly as if they all were preceded by an at sign (`@').

     .USE      Turn the target into bmake's version of a macro.  When the tar-
               get is used as a source for another target, the other target
               acquires the commands, sources, and attributes (except for
               .USE) of the source.  If the target already has commands, the
               .USE target's commands are appended to them.

     .USEBEFORE
               Like .USE, but instead of appending, prepend the .USEBEFORE
               target commands to the target.

     .WAIT     If .WAIT appears in a dependency line, the sources that precede
               it are made before the sources that succeed it in the line.
               Since the dependents of files are not made until the file it-
               self could be made, this also stops the dependents being built
               unless they are needed for another branch of the dependency
               tree.  So given:

               x: a .WAIT b
                       echo x
               a:
                       echo a
               b: b1
                       echo b
               b1:
                       echo b1

               the output is always `a', `b1', `b', `x'.

               The ordering imposed by .WAIT is only relevant for parallel
               makes.

SPECIAL TARGETS
     Special targets may not be included with other targets, i.e. they must be
     the only target specified.

     .BEGIN   Any command lines attached to this target are executed before
              anything else is done.

     .DEFAULT
              This is sort of a .USE rule for any target (that was used only
              as a source) that bmake can't figure out any other way to cre-
              ate.  Only the shell script is used.  The .IMPSRC variable of a
              target that inherits .DEFAULT's commands is set to the target's
              own name.

     .DELETE_ON_ERROR
              If this target is present in the makefile, it globally causes
              make to delete targets whose commands fail.  (By default, only
              targets whose commands are interrupted during execution are
              deleted.  This is the historical behavior.)  This setting can be
              used to help prevent half-finished or malformed targets from be-
              ing left around and corrupting future rebuilds.

     .END     Any command lines attached to this target are executed after ev-
              erything else is done successfully.

     .ERROR   Any command lines attached to this target are executed when an-
              other target fails.  The .ERROR_TARGET variable is set to the
              target that failed.  See also MAKE_PRINT_VAR_ON_ERROR.

     .IGNORE  Mark each of the sources with the .IGNORE attribute.  If no
              sources are specified, this is the equivalent of specifying the
              -i option.

     .INTERRUPT
              If bmake is interrupted, the commands for this target are exe-
              cuted.

     .MAIN    If no target is specified when bmake is invoked, this target is
              built.

     .MAKEFLAGS
              This target provides a way to specify flags for bmake at the
              time when the makefiles are read.  The flags are as if typed to
              the shell, though the -f option has no effect.

     .NOPATH  Apply the .NOPATH attribute to any specified sources.

     .NOTPARALLEL
              Disable parallel mode.

     .NO_PARALLEL
              Synonym for .NOTPARALLEL, for compatibility with other pmake
              variants.

     .NOREADONLY
              clear the read-only attribute from the global variables speci-
              fied as sources.

     .OBJDIR  The source is a new value for `.OBJDIR'.  If it exists, bmake
              changes the current working directory to it and updates the
              value of `.OBJDIR'.

     .ORDER   In parallel mode, the named targets are made in sequence.  This
              ordering does not add targets to the list of targets to be made.

              Since the dependents of a target do not get built until the tar-
              get itself could be built, unless `a' is built by another part
              of the dependency graph, the following is a dependency loop:

              .ORDER: b a
              b: a

     .PATH    The sources are directories which are to be searched for files
              not found in the current directory.  If no sources are speci-
              fied, any previously specified directories are removed from the
              search path.  If the source is the special .DOTLAST target, the
              current working directory is searched last.

     .PATH.suffix
              Like .PATH but applies only to files with a particular suffix.
              The suffix must have been previously declared with .SUFFIXES.

     .PHONY   Apply the .PHONY attribute to any specified sources.

     .POSIX   If this is the first non-comment line in the main makefile, the
              variable %POSIX is set to the value `1003.2' and the makefile
              `<posix.mk>' is included if it exists, to provide POSIX-compati-
              ble default rules.  If bmake is run with the -r flag, only
              `posix.mk' contributes to the default rules.

     .PRECIOUS
              Apply the .PRECIOUS attribute to any specified sources.  If no
              sources are specified, the .PRECIOUS attribute is applied to ev-
              ery target in the file.

     .READONLY
              set the read-only attribute on the global variables specified as
              sources.

     .SHELL   Sets the shell that bmake uses to execute commands in jobs mode.
              The sources are a set of field=value pairs.

              name        This is the minimal specification, used to select
                          one of the built-in shell specs; sh, ksh, and csh.

              path        Specifies the absolute path to the shell.

              hasErrCtl   Indicates whether the shell supports exit on error.

              check       The command to turn on error checking.

              ignore      The command to disable error checking.

              echo        The command to turn on echoing of commands executed.

              quiet       The command to turn off echoing of commands exe-
                          cuted.

              filter      The output to filter after issuing the quiet com-
                          mand.  It is typically identical to quiet.

              errFlag     The flag to pass the shell to enable error checking.

              echoFlag    The flag to pass the shell to enable command echo-
                          ing.

              newline     The string literal to pass the shell that results in
                          a single newline character when used outside of any
                          quoting characters.
              Example:

              .SHELL: name=ksh path=/bin/ksh hasErrCtl=true \
                      check="set -e" ignore="set +e" \
                      echo="set -v" quiet="set +v" filter="set +v" \
                      echoFlag=v errFlag=e newline="'\n'"

     .SILENT  Apply the .SILENT attribute to any specified sources.  If no
              sources are specified, the .SILENT attribute is applied to every
              command in the file.

     .STALE   This target gets run when a dependency file contains stale en-
              tries, having .ALLSRC set to the name of that dependency file.

     .SUFFIXES
              Each source specifies a suffix to bmake.  If no sources are
              specified, any previously specified suffixes are deleted.  It
              allows the creation of suffix-transformation rules.

              Example:

              .SUFFIXES: .c .o
              .c.o:
                      cc -o ${.TARGET} -c ${.IMPSRC}

     .SYSPATH
              The sources are directories which are to be added to the system
              include path which bmake searches for makefiles.  If no sources
              are specified, any previously specified directories are removed
              from the system include path.

ENVIRONMENT
     bmake uses the following environment variables, if they exist: MACHINE,
     MACHINE_ARCH, MAKE, MAKEFLAGS, MAKEOBJDIR, MAKEOBJDIRPREFIX, MAKESYSPATH,
     PWD, and TMPDIR.

     MAKEOBJDIRPREFIX and MAKEOBJDIR may only be set in the environment or on
     the command line to bmake and not as makefile variables; see the descrip-
     tion of `.OBJDIR' for more details.

FILES
     .depend        list of dependencies
     makefile       first default makefile if no makefile is specified on the
                    command line
     Makefile       second default makefile if no makefile is specified on the
                    command line
     sys.mk         system makefile
     /usr/share/mk  system makefile directory

COMPATIBILITY
     The basic make syntax is compatible between different make variants; how-
     ever the special variables, variable modifiers and conditionals are not.

   Older versions
     An incomplete list of changes in older versions of bmake:

     The way that .for loop variables are substituted changed after NetBSD 5.0
     so that they still appear to be variable expansions.  In particular this
     stops them being treated as syntax, and removes some obscure problems us-
     ing them in .if statements.

     The way that parallel makes are scheduled changed in NetBSD 4.0 so that
     .ORDER and .WAIT apply recursively to the dependent nodes.  The algo-
     rithms used may change again in the future.

   Other make dialects
     Other make dialects (GNU make, SVR4 make, POSIX make, etc.) do not sup-
     port most of the features of bmake as described in this manual.  Most no-
     tably:

           +o   The .WAIT and .ORDER declarations and most functionality per-
               taining to parallelization.  (GNU make supports parallelization
               but lacks the features needed to control it effectively.)

           +o   Directives, including for loops and conditionals and most of
               the forms of include files.  (GNU make has its own incompatible
               and less powerful syntax for conditionals.)

           +o   All built-in variables that begin with a dot.

           +o   Most of the special sources and targets that begin with a dot,
               with the notable exception of .PHONY, .PRECIOUS, and .SUFFIXES.

           +o   Variable modifiers, except for the `:old=new' string substitu-
               tion, which does not portably support globbing with `%' and
               historically only works on declared suffixes.

           +o   The $> variable even in its short form; most makes support this
               functionality but its name varies.

     Some features are somewhat more portable, such as assignment with +=, ?=,
     and !=.  The .PATH functionality is based on an older feature VPATH found
     in GNU make and many versions of SVR4 make; however, historically its be-
     havior is too ill-defined (and too buggy) to rely upon.

     The $@ and $< variables are more or less universally portable, as is the
     $(MAKE) variable.  Basic use of suffix rules (for files only in the cur-
     rent directory, not trying to chain transformations together, etc.) is
     also reasonably portable.

SEE ALSO
     mkdep(1)

HISTORY
     bmake is derived from NetBSD make(1).  It uses autoconf to facilitate
     portability to other platforms.

     A make command appeared in Version 7 AT&T UNIX.  This make implementation
     is based on Adam de Boor's pmake program, which was written for Sprite at
     Berkeley.  It was designed to be a parallel distributed make running jobs
     on different machines using a daemon called "customs".

     Historically the target/dependency FRC has been used to FoRCe rebuilding
     (since the target/dependency does not exist ... unless someone creates an
     FRC file).

BUGS
     The make syntax is difficult to parse.  For instance, finding the end of
     a variable's use should involve scanning each of the modifiers, using the
     correct terminator for each field.  In many places make just counts {}
     and () in order to find the end of a variable expansion.

     There is no way of escaping a space character in a filename.

FreeBSD 13.0                   January 26, 2023                   FreeBSD 13.0