NAME
make —
maintain program
dependencies
SYNOPSIS
make |
[-BeikNnqrstWwX]
[-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
make is a program designed to simplify the maintenance of
other programs. Its input is a list of specifications as to the files upon
which programs and other files depend. If no
-f
makefile makefile option is given,
make will try to open
‘
makefile
’ then
‘
Makefile
’ in order to
find the specifications. 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
make and makefiles, please refer to
PMake - A Tutorial.
make will prepend 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 executing the commands to make the sources of a
dependency line in sequence.
-
-
- -C
directory
- Change to directory before reading
the makefiles or doing anything else. If multiple -C
options are specified, each is interpreted relative to the previous one:
-C / -C
etc is equivalent to -C
/etc.
-
-
- -D
variable
- Define variable to be 1, in the
global context.
-
-
- -d
[-]flags
- Turn on debugging, and specify which portions of
make are to print debugging information. Unless the
flags are preceded by ‘
-
’ they are
added to the MAKEFLAGS environment variable and will
be processed by any child make processes. By default, debugging
information is printed to standard error, but this can be changed using
the F debugging flag. The debugging output is always
unbuffered; in addition, if debugging is enabled but debugging output is
not directed to standard output, then the standard output is line
buffered. Flags is one or more of the following:
-
-
- 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 current working
directory.
-
-
- 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
‘+
’, then the file will be opened
in append mode; otherwise the file will be overwritten. If the file
name is ‘stdout
’ or
‘stderr
’ then debugging output
will be written to the standard output or standard error output file
descriptors respectively (and the
‘+
’ option has no effect).
Otherwise, the output will be written to the named file. If the file
name ends ‘.%d
’ then 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.
-
-
- j
- Print debugging information about running multiple
shells.
-
-
- 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,
including 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
variable, 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
maintenance.
-
-
- 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.
-
-
- x
- Run shell commands with -x so the
actual commands are printed as they are executed.
-
-
- -e
- Specify that environment variables override macro
assignments within makefiles.
-
-
- -f
makefile
- Specify a makefile to read instead of the default
‘
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.
Equivalent 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
make may have running at any one time. The value is
saved in .MAKE.JOBS. Turns compatibility mode off,
unless the B flag 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 traditional one
shell invocation per line. This can break traditional scripts which change
directories on each command invocation 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 will override the default system include path:
/usr/share/mk. Furthermore the system include path will be appended to the
search path used for “file”-style
include statements (see the -I option).
If a file or directory name in the -m argument (or the
MAKESYSPATH
environment variable) starts with the
string “.../” then make will search for the
specified file or directory named in the remaining part of the argument
string. The search starts with the current directory of the Makefile and
then works upward towards the root of the file system. If the search is
successful, then the resulting directory replaces the “.../”
specification in the -m argument. If used, this feature
allows make to easily search in the current source tree
for customized sys.mk files (e.g., by using “.../mk/sys.mk” as
an argument).
-
-
- -n
- Display the commands that would have been executed, but do
not actually execute them unless the target depends on the .MAKE special
source (see below).
-
-
- -N
- Display the commands which 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, but exit 0 if the specified
targets are up-to-date and 1, otherwise.
-
-
- -r
- Do not use the built-in rules specified in the system
makefile.
-
-
- -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 will be printed one per line, with a blank line for each null or
undefined variable. The value printed is extracted from the global context
after all makefiles have been read. By default, the raw variable contents
(which may include additional unexpanded variable references) are shown.
If variable contains a
‘
$
’ then the value will be recursively
expanded to its complete resultant text before printing. The expanded
value will also be printed 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
values taken temporarily by global variables during makefile processing,
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 the variable is always
expanded to its complete value.
-
-
- -W
- Treat any warnings during makefile parsing as errors.
-
-
- -w
- Print entering and leaving directory messages, pre and post
processing.
-
-
- -X
- Don't export variables passed on the command line to the
environment individually. Variables passed on the command line are still
exported via the MAKEFLAGS environment variable.
This option 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.
Variable assignments should follow options for POSIX compatibility but no
ordering is enforced.
There are seven different types of lines in a makefile: file dependency
specifications, shell commands, variable assignments, include statements,
conditional directives, for loops, and comments.
In general, 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 usually created from them. The exact relationship between
the target and the source is determined by the operator that separates them.
The three operators are as follows:
-
-
- :
- A target is considered out-of-date if its modification time
is less than those of any of its sources. Sources for a target accumulate
over dependency lines when this operator is used. The target is removed if
make is interrupted.
-
-
- !
- Targets are always re-created, but not until all sources
have been examined and re-created as necessary. Sources for a target
accumulate over dependency lines when this operator is used. The target is
removed if make is interrupted.
-
-
- ::
- If no sources are specified, the target is always
re-created. Otherwise, a target is considered out-of-date if any of its
sources has been modified more recently than the target. Sources for a
target do not accumulate over dependency lines when this operator is used.
The target will not be removed if make is
interrupted.
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 must be used to describe 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 commands,
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 appear in many dependency lines if
desired, 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 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. A ‘
@
’
causes the command not to be echoed before it is executed. A
‘
+
’ 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. A
‘
-
’ in compatibility
mode causes any non-zero exit status of the command line to be ignored.
When
make 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 command contains any shell meta
characters
(‘
#=|^(){};&<>*?[]:$`\\n
’) it
will be passed to the shell; otherwise
make will attempt
direct execution. If a line starts with
‘
-
’ and the shell has
ErrCtl enabled then failure of the command line will be ignored as in
compatibility mode. Otherwise
‘
-
’ affects the entire
job; the script will stop at the first command line that fails, but the target
will not be deemed to have failed.
Makefiles should be written so that the mode of
make operation
does not change their behavior. For example, any command which needs to use
“cd” or “chdir” without potentially changing the
directory for subsequent commands should be put in parentheses so it executes
in a subshell. To force the use of one 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
make will
chdir(2) to
‘
.OBJDIR
’ before
executing any targets, each child process starts with that as its current
working directory.
VARIABLE ASSIGNMENTS
Variables in make are much like variables in the shell, and, by tradition,
consist of all upper-case letters.
Variable assignment
modifiers
The five operators that can be used to assign values to variables are as
follows:
-
-
- =
- Assign the value to the variable. Any previous value is
overridden.
-
-
- +=
- Append the value to the current value of the variable.
-
-
- ?=
- Assign the value to the variable if it is not already
defined.
-
-
- :=
- Assign with expansion, i.e. expand the value before
assigning it to the variable. Normally, expansion is not done until the
variable is referenced. 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 and
assign the result to the variable. Any newlines in the result are replaced
with spaces.
Any white-space before the assigned
value is removed; if
the value is being appended, a single space is inserted between the previous
contents of the variable and the appended value.
Variables are expanded by surrounding the variable name with either curly braces
(‘
{}
’) or parentheses
(‘
()
’) and preceding it with a dollar sign
(‘
$
’). If the variable name contains only
a single letter, the surrounding braces or parentheses are not required. This
shorter form is not recommended.
If the variable name contains a dollar, then the name itself is expanded first.
This allows almost arbitrary variable names, however names containing dollar,
braces, parenthesis, or whitespace are really best avoided!
If the result of expanding a variable contains a dollar sign
(‘
$
’) the string is expanded again.
Variable substitution occurs at three distinct times, depending on where the
variable is being used.
- Variables in dependency lines are expanded as the line is
read.
- Variables in shell commands are expanded when the shell
command is executed.
- “.for” loop index variables are expanded on
each loop iteration. Note that other variables are not expanded inside
loops so the following example code:
.for i in 1 2 3
a+= ${i}
j= ${i}
b+= ${j}
.endfor
all:
@echo ${a}
@echo ${b}
will print:
Because while ${a} contains “1 2 3” after the loop is executed,
${b} contains “${j} ${j} ${j}” which expands to “3 3
3” since after the loop completes ${j} contains
“3”.
Variable classes
The four different classes of variables (in order of increasing precedence) are:
-
-
- Environment variables
- Variables defined as part of make'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 are all built in and their values vary magically from target to
target. It is not currently possible to define new local variables. The seven
local variables are as follows:
-
-
- .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 will not be recognized.
-
-
- .TARGET
- The name of the target; also known as
‘
@
’. For
compatibility 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,
make sets or knows about the following variables:
-
-
- $
- A single dollar sign
‘
$
’, i.e.
‘$$
’ expands to a single dollar
sign.
-
-
- .ALLTARGETS
- The list of all targets encountered in the Makefile. If
evaluated during Makefile parsing, lists only those targets encountered
thus far.
-
-
- .CURDIR
- A path to the directory where make was
executed. Refer to the description of
‘
PWD
’ for more
details.
-
-
- .INCLUDEDFROMDIR
- The directory of the file this Makefile was included
from.
-
-
- .INCLUDEDFROMFILE
- The filename of the file this Makefile was included
from.
-
-
MAKE
- The name that make was executed with
(argv[0]). For compatibility make
also sets .MAKE with the same value. The preferred
variable to use is the environment variable
MAKE
because it is more compatible with other versions of
make and cannot be confused with the special target with
the same name.
-
-
- .MAKE.DEPENDFILE
- Names the makefile (default
‘
.depend
’) from
which generated dependencies are read.
-
-
- .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
make.
-
-
- .MAKE.JOBS
- The argument to the -j option.
-
-
- .MAKE.JOB.PREFIX
- If make is run with
j then 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:
.MAKE.JOB.PREFIX=${.newline}---${.MAKE:T}[${.MAKE.PID}]
would produce tokens like ‘---make[1234] target
---
’ making it easier to track the degree of parallelism
being achieved.
-
-
MAKEFLAGS
- The environment variable
‘
MAKEFLAGS
’
may contain anything that may be specified on make's
command line. Anything specified on make's command line
is appended to the
‘MAKEFLAGS
’
variable which is then entered into the environment for all programs which
make executes.
-
-
- .MAKE.LEVEL
- The recursion depth of make. The initial
instance of make will be 0, and an incremented value is
put into the environment to be seen by the next generation. This allows
tests like:
.if ${.MAKE.LEVEL} == 0
to protect
things which should only be evaluated in the initial instance of
make.
-
-
- .MAKE.MAKEFILE_PREFERENCE
- The ordered list of makefile names (default
‘
makefile
’,
‘Makefile
’) that
make will look for.
-
-
- .MAKE.MAKEFILES
- The list of makefiles read by make, which
is useful for tracking dependencies. Each makefile is recorded only once,
regardless of the number of times read.
-
-
- .MAKE.MODE
- Processed after reading all makefiles. Can affect the mode
that make runs in. It can contain a number of keywords:
- compat
- Like
-B, puts make into
"compat" mode.
- meta
- Puts
make 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
make. The captured output can be very useful when
diagnosing errors.
- curdirOk=
bf
- Normally
make will 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, then a missing .meta file makes the
target out-of-date.
- missing-filemon=
bf
- If
bf is True, then 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 environment 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 the 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.
-
-
- .MAKE.META.BAILIWICK
- In "meta" mode, provides a list of prefixes which
match the directories controlled by make. If a file that
was generated outside of .OBJDIR but within said
bailiwick is missing, the current target 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
processing 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_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.IGNORE_FILTER
- Provides a list of variable modifiers to apply to each
pathname. Ignore if the expansion is an empty string.
-
-
- .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}
-
-
- .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 make 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 make.
-
-
- .MAKE.PPID
- The parent process-id of make.
-
-
- .MAKE.SAVE_DOLLARS
- value should be a boolean that controls whether
‘
$$
’ are preserved when doing
‘:=
’ assignments. The default is true,
for compatibility with other makes. If set to false,
‘$$
’ becomes
‘$
’ per normal evaluation rules.
-
-
- MAKE_PRINT_VAR_ON_ERROR
- When make 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 variables named in
‘MAKE_PRINT_VAR_ON_ERROR
’.
-
-
- .newline
- This variable is simply assigned a newline character as its
value. This allows expansions using the :@ modifier to
put a newline between iterations of the loop rather than a space. For
example, the printing of
‘
MAKE_PRINT_VAR_ON_ERROR
’
could be done as
${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:
${MAKEOBJDIRPREFIX}${.CURDIR}
(Only if
‘MAKEOBJDIRPREFIX
’
is set in the environment or on the command line.)
${MAKEOBJDIR}
(Only if
‘MAKEOBJDIR
’
is set in the environment or on the command line.)
${.CURDIR}
/obj.${MACHINE}
${.CURDIR}
/obj
- /usr/obj/
${.CURDIR}
${.CURDIR}
Variable expansion is performed on the value before it's 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, make will
chdir(2) to the specified
directory if it exists, and set
‘.OBJDIR
’ and
‘PWD
’ to that
directory before executing any targets.
-
-
- .PARSEDIR
- A path to the directory 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. If you want to retain their current values, assign them to a
variable using assignment with expansion:
(‘:=
’).
-
-
- .PATH
- A variable that represents the list of directories that
make will search for files. The search list should be
updated using the target
‘
.PATH
’ rather
than the variable.
-
-
PWD
- Alternate path to the current directory.
make 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, then make
sets ‘.CURDIR
’
to the value of
‘PWD
’ instead.
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 make executes.
-
-
.TARGETS
- The list of targets explicitly specified on the command
line, if any.
-
-
VPATH
- Colon-separated (“:”) lists of directories that
make will search for files. The variable is supported
for compatibility with old make programs only, use
‘
.PATH
’
instead.
Variable modifiers
Variable expansion may be modified to select or modify each word of the variable
(where a “word” is white-space delimited sequence of characters).
The general format of a variable expansion is as follows:
${variable[:modifier[:...]]}
Each modifier begins with a colon, which may be escaped with a backslash
(‘
\
’).
A set of 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 must appear in the referencing variable. If any of the
modifiers in the modifier_variable contain a dollar sign
(‘
$
’), these must be doubled to avoid
early expansion.
The supported modifiers are:
-
-
- :E
- Replaces each word in the variable with its suffix.
-
-
- :H
- Replaces each word in the variable with everything but the
last component.
-
-
- :Mpattern
- Select 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, a construct like
${VAR:M*}
will normalize the inter-word spacing, removing all leading and trailing
space, and converting multiple consecutive spaces to single spaces.
-
-
- :Npattern
- This is identical to
‘
:M
’, but selects
all words which do not match pattern.
-
-
- :O
- Order every word in variable alphabetically. To sort words
in reverse order use the
‘
:O:[-1..1]
’
combination of modifiers.
-
-
- :Ox
- Randomize words in variable. The results will be different
each time you are referring 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 variable, so that
it can be passed safely through recursive invocations of
make.
-
-
- :R
- Replaces each word in the variable with everything but its
suffix.
-
-
- :range[=count]
- The value is an integer sequence representing the words of
the original value, or the supplied count.
-
-
- :gmtime[=utc]
- The value is a format string for
strftime(3), using
gmtime(3). If a
utc value is not provided or is 0, the current time
is used.
-
-
- :hash
- Compute a 32-bit hash of the value and encode it as hex
digits.
-
-
- :localtime[=utc]
- The value is a format string for
strftime(3), using
localtime(3). If a
utc value is not provided or is 0, the current time
is used.
-
-
- :tA
- Attempt to convert variable to an absolute path using
realpath(3), if that
fails, the value is unchanged.
-
-
- :tl
- Converts variable to lower-case letters.
-
-
- :tsc
- Words in the variable are normally separated by a space on
expansion. This modifier sets the separator to the character
c. If c is omitted, then no
separator is used. The common escapes (including octal numeric codes),
work as expected.
-
-
- :tu
- Converts variable to upper-case letters.
-
-
- :tW
- Causes the value to be treated as a single word (possibly
containing embedded white space). See also
‘
:[*]
’.
-
-
- :tw
- Causes the value to be treated as a sequence of words
delimited by white space. See also
‘
:[@]
’.
-
-
- :S/old_string/new_string/[1gW]
- Modify the first occurrence of
old_string in the variable's value, replacing it
with new_string. If a
‘
g
’ is appended to the last slash of
the pattern, all occurrences in each word are replaced. If a
‘1
’ is appended to the last slash of
the pattern, only the first word is affected. If a
‘W
’ is appended to the last slash of
the pattern, then the value is treated as a single word (possibly
containing embedded white space). If old_string
begins with a caret (‘^
’),
old_string is anchored 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 any
‘^
’ or
‘$
’). Any character may be used as a
delimiter for the parts of the modifier string. The anchoring, ampersand
and delimiter characters may be escaped with a backslash
(‘\
’).
Variable expansion occurs in the normal fashion inside both
old_string and new_string with
the single exception that a backslash is used to prevent the expansion of
a dollar sign (‘$
’), not a preceding
dollar sign as is usual.
-
-
- :C/pattern/replacement/[1gW]
- The :C modifier is just like the
:S modifier except that the old and new strings, instead
of being simple strings, are an extended regular expression (see
regex(3)) string
pattern and an
ed(1)-style string
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 single word (possibly containing
embedded white space). Note that ‘1
’
and ‘g
’ are orthogonal; the former
specifies whether multiple words are potentially affected, the latter
whether multiple substitutions can potentially occur within each affected
word.
As for the :S modifier, the pattern
and replacement are subjected to variable expansion
before being parsed as regular expressions.
-
-
- :T
- Replaces each word in the variable with its last
component.
-
-
- :u
- Remove adjacent duplicate words (like
uniq(1)).
-
-
- :?true_string:false_string
- If the variable name (not its value), when parsed as a .if
conditional 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 will, of course, usually contain variable expansions. A common error
is trying to use expressions like
${NUMBERS:M42:?match:no}
which actually tests defined(NUMBERS), to determine is 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 variable substitution. It must be the last modifier
specified. If old_string or
new_string do not contain the pattern matching
character % then it is assumed that they are
anchored at the end of each word, so only suffixes or entire words may be
replaced. Otherwise % is the substring of
old_string to be replaced in
new_string.
Variable expansion occurs in the normal fashion inside both
old_string and new_string with
the single exception that a backslash is used to prevent the expansion of
a dollar sign (‘
$
’), not a preceding
dollar sign as is usual.
-
-
- :@temp@string@
- This is the loop expansion mechanism from the OSF
Development Environment (ODE) make. Unlike .for loops
expansion occurs at the time of reference. Assign
temp to each word in the variable and evaluate
string. The ODE convention is that
temp should start and end with a period. For
example.
${LINKS:@.LINK.@${LN} ${TARGET}
${.LINK.}@}
However a single character variable is often more readable:
${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}
-
-
- :_[=var]
- Save 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 instance:
${_${.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, then
the name of the variable is used. In order for this modifier to work, the
name (node) must at least have appeared on the rhs of a dependency.
-
-
- :!cmd!
- The output of running cmd is the
value.
-
-
- :sh
- If the variable is non-empty it 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 when shell commands are being parsed. These assignment modifiers
always expand to nothing, so if appearing in a rule line by themselves
should be preceded with something to keep make happy.
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
operations related to the way in which the value is divided into words.
Ordinarily, a value is treated as a sequence of words delimited by white
space. Some modifiers suppress this behavior, causing a value to be
treated as a single word (possibly containing embedded white space). 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 integers (where
index -1 represents the last word).
The range is subjected to variable expansion, and the
expanded result 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,
then the words are output in reverse order. For example,
‘:[-1..1]
’
selects all the words from last to first.
-
-
- *
- Causes subsequent modifiers to treat the value as a
single word (possibly containing embedded white space). 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 white space. Analogous to the effect of
"$@" in Bourne shell.
-
-
- #
- Returns the number of words in the value.
INCLUDE
STATEMENTS, CONDITIONALS AND FOR LOOPS
Makefile inclusion, conditional structures and for loops reminiscent of the C
programming language are provided in
make. All such
structures are identified by a line beginning with a single dot
(‘
.
’) character. Files are included with
either
.include ⟨
file⟩
or
.include "
file".
Variables between the angle brackets or double quotes are expanded to form the
file name. If angle brackets are used, the included makefile is expected 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 versions of
make
‘
include file ...
’ is also accepted.
If the include statement is written as
.-include or as
.sinclude then errors locating and/or opening include files
are ignored.
If the include statement is written as
.dinclude not only are
errors locating and/or opening include files ignored, but stale dependencies
within the included file will be ignored just like
.MAKE.DEPENDFILE.
Conditional expressions are also preceded by a single dot as the first character
of a line. The possible conditionals are as follows:
-
-
- .error
message
- The message is printed along with the name of the makefile
and line number, then make will exit.
-
-
- .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
’ is also
accepted.
Appending a variable name to .MAKE.EXPORTED is
equivalent to exporting 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
environment which is different from that used by make
internally.
-
-
- .export-literal
variable ...
- The same as
‘
.export-env
’, except that variables
in the value are not expanded.
-
-
- .info
message
- The message is printed along with the name of the makefile
and line number.
-
-
- .undef
variable
- Un-define the specified global variable. Only global
variables may be un-defined.
-
-
- .unexport
variable ...
- The opposite of
‘
.export
’. The specified global
variable will be removed 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
environment inherited from the parent. This operation will cause 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
’
will also be pushed into the new environment.
-
-
- .warning
message
- The message prefixed by
‘
warning:
’ is
printed along with the name of the makefile and line number.
-
-
- .if
[!]expression
[operator expression ...]
- Test the value of an expression.
-
-
- .ifdef
[!]variable
[operator variable ...]
- Test the value of a variable.
-
-
- .ifndef
[!]variable
[operator variable ...]
- Test the value of a variable.
-
-
- .ifmake
[!]target
[operator target ...]
- Test the target being built.
-
-
- .ifnmake
[!] target
[operator target ...]
- Test the target being built.
-
-
- .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
“||”.
As in C,
make will only evaluate a conditional as far as is
necessary to determine its value. Parentheses may be used to change the order
of evaluation. The boolean operator
‘
!
’ may be used to
logically negate an entire conditional. It is of higher precedence than
‘
&&
’.
The value of
expression may be any of the following:
-
-
- defined
- Takes a variable name as an argument and evaluates to true
if the variable has been defined.
-
-
- make
- Takes a target name as an argument and evaluates to true if
the target was specified as part of make's command line
or was declared the default target (either implicitly or explicitly, see
.MAIN) before the line containing the
conditional.
-
-
- empty
- Takes a variable, with possible modifiers, and evaluates to
true if the expansion of the variable would result in an empty
string.
-
-
- exists
- Takes a file name as an argument and evaluates to true if
the file exists. The file is searched for on the system search path (see
.PATH).
-
-
- target
- Takes a target name as an argument and evaluates to true if
the target has been defined.
-
-
- commands
- Takes a target name as an argument and 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 expansion is performed on both sides of the comparison, after which
the integral values are compared. A value is interpreted as hexadecimal if it
is preceded by 0x, otherwise it is decimal; octal numbers are not supported.
The standard C relational operators are all supported. If after variable
expansion, either the left or right hand side of a
‘
==
’ or
‘
!=
’ operator is not an
integral value, then string comparison is performed between the expanded
variables. If no relational operator is given, it is assumed that the expanded
variable is being compared against 0 or an empty string in the case of a
string comparison.
When
make is evaluating one of these conditional expressions,
and it encounters a (white-space separated) word it doesn't recognize, either
the “make” or “defined” expression is applied to it,
depending on the form of the conditional. If the form is
‘
.ifdef
’,
‘
.ifndef
’, or
‘
.if
’ the
“defined” expression is applied. Similarly, if the form is
‘
.ifmake
’ or
‘
.ifnmake,
the
’ “make” expression is applied.
If the conditional evaluates to true the parsing of the makefile continues as
before. If it evaluates to false, the following lines are skipped. In both
cases this continues until a
‘
.else
’ or
‘
.endif
’ is found.
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-rules⟩
-
- .endfor
-
After the for
expression is evaluated, it is 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-rules 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.
Comments begin with a hash (‘
#
’) character,
anywhere but in a shell command 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
anyway.
-
-
- .IGNORE
- Ignore any errors from the commands associated with this
target, 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 makes.
-
-
- .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 will still
be out of date. The same effect applies 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 will be compared
@echo this will not ${.OODATE:M.NOMETA_CMP}
@echo this will also be compared
The :M pattern suppresses any expansion of the unwanted
variable.
-
-
- .NOPATH
- Do not search for the target in the directories specified
by .PATH.
-
-
- .NOTMAIN
- Normally make 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
make can't figure out how to create it, it will ignore
this fact and assume 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 will not be created with the
-t option. Suffix-transformation rules are not applied
to .PHONY targets.
-
-
- .PRECIOUS
- When make is interrupted, it normally
removes any partially made targets. This source prevents the target from
being removed.
-
-
- .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 make's version of a
macro. When the target 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
- Exactly like .USE, but 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 itself
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 make can't
figure out any other way to create. 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 being left around and corrupting
future rebuilds.
-
-
- .END
- Any command lines attached to this target are executed
after everything else is done.
-
-
- .ERROR
- Any command lines attached to this target are executed when
another 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 make is interrupted, the commands for
this target will be executed.
-
-
- .MAIN
- If no target is specified when make is
invoked, this target will be built.
-
-
- .MAKEFLAGS
- This target provides a way to specify flags for
make when the makefile is used. The flags are as if
typed to the shell, though the -f option will have 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.
-
-
- .OBJDIR
- The source is a new value for
‘
.OBJDIR
’. If it
exists, make will
chdir(2) to it and update the
value of
‘.OBJDIR
’.
-
-
- .ORDER
- 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 target itself could be built, unless
‘
a
’ is built by another part of the
dependency graph, the following is a dependency loop:
The ordering imposed by .ORDER is only relevant for
parallel makes.
-
-
- .PATH
- The sources are directories which are to be searched for
files not found in the current directory. If no sources are specified, any
previously specified directories are deleted. If the source is the special
.DOTLAST target, then 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.
-
-
- .PRECIOUS
- Apply the .PRECIOUS attribute to any
specified sources. If no sources are specified, the
.PRECIOUS attribute is applied to every target in the
file.
-
-
- .SHELL
- Sets the shell that make will use to
execute commands. 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 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
executed.
-
-
- filter
- The output to filter after issuing the
quiet command. 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
echoing.
-
-
- 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
entries, having .ALLSRC set to the name of that
dependency file.
-
-
- .SUFFIXES
- Each source specifies a suffix to make.
If no sources are specified, any previously specified suffixes are
deleted. It allows the creation of suffix-transformation rules.
Example:
.SUFFIXES: .o
.c.o:
cc -o ${.TARGET} -c ${.IMPSRC}
ENVIRONMENT
make 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
make and not as makefile variables; see the description of
‘
.OBJDIR
’ for more
details.
FILES
- .depend
- list of dependencies
- Makefile
- list of dependencies
- makefile
- list of dependencies
- sys.mk
- system makefile
- /usr/share/mk
- system makefile directory
COMPATIBILITY
The basic make syntax is compatible between different versions of make; however
the special variables, variable modifiers and conditionals are not.
Older versions
An incomplete list of changes in older versions of
make:
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 using 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 algorithms used may change again in the future.
Other make dialects
Other make dialects (GNU make, SVR4 make, POSIX make, etc.) do not support most
of the features of
make as described in this manual. Most
notably:
- The .WAIT and .ORDER
declarations and most functionality pertaining to parallelization. (GNU
make supports parallelization but lacks these features needed to control
it effectively.)
- 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.)
- All built-in variables that begin with a dot.
- Most of the special sources and targets that begin with
a dot, with the notable exception of .PHONY,
.PRECIOUS, and .SUFFIXES.
- Variable modifiers, except for the
:old=new
string substitution, which does not portably support globbing with
‘%
’ and historically only works on
declared suffixes.
- 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 behavior 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 current directory, not trying to chain
transformations together, etc.) is also reasonably portable.
SEE ALSO
mkdep(1)
HISTORY
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 without actually acting
of the data. For instance finding the end of a variable use should involve
scanning each 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.