NAME¶
make —
maintain program
dependencies
SYNOPSIS¶
make |
[-ABPSXeiknpqrstv]
[-C
directory]
[-D
variable]
[-d flags]
[-E
variable]
[-f
makefile]
[-I
directory]
[-j max_jobs]
[-m directory]
[-V
variable]
[-x
warning_options]
[variable=value]
[target ...] |
DESCRIPTION¶
The
make utility is a program designed to simplify the
maintenance of other programs. Its input is a list of specifications
describing dependency relationships between the generation of files and
programs.
First of all, the initial list of specifications will be read from the system
makefile,
sys.mk, unless inhibited with the
-r option. The standard
sys.mk as shipped
with
FreeBSD also handles
make.conf(5), the default path to which can be altered via
the
make variable
__MAKE_CONF.
Then the first of
BSDmakefile,
makefile, and
Makefile that can be found in the current directory, object
directory (see
.OBJDIR), or search path (see the
-I option) will be read for the main list of dependency
specifications. A different makefile or list of them can be supplied via the
-f option(s). Finally, if the file
.depend
can be found in any of the aforesaid locations, it will also be read (see
mkdep(1)).
When
make searches for a makefile, its name takes precedence
over its location. For instance,
BSDmakefile in the object
directory will be favored over
Makefile in the current
directory.
The options are as follows:
- -A
- Make archive errors non-fatal, causing
make to just skip the remainder or all of the archive
and continue after printing a message.
- -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. This is turned on by default unless
-j is used.
- -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. Argument
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 conditional
evaluation.
- d
- Print debugging information about directory searching
and caching.
- f
- Print debugging information about the execution of for
loops.
- g1
- Print the input graph before making anything.
- g2
- Print the input graph after making everything, or
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 making targets,
including modification dates.
- s
- Print debugging information about suffix-transformation
rules.
- t
- Print debugging information about target list
maintenance.
- v
- Print debugging information about variable
assignment.
- -E
variable
- Specify a variable whose environment value (if any) will
override macro assignments within makefiles.
- -e
- Specify that environment values override macro assignments
within makefiles for all variables.
- -f
makefile
- Specify a makefile to read instead of the default one. If
makefile is not an absolute pathname,
make will search for it as described above. In case
makefile is ‘-’,
standard input is read. Multiple -f options can be
supplied, and the makefiles will be read in that order. Unlike the other
command-line options, -f is neither stored in
.MAKEFLAGS nor pushed down to sub-makes via
MAKEFLAGS
. See below for more details on these
variables.
- -I
directory
- Specify a directory in which to search for makefiles and
included makefiles. Multiple -I options can be specified
to form a search path. The system makefile directory (or directories, see
the -m option) is automatically appended at the tail of
this path.
- -i
- Ignore non-zero exit of shell commands in the makefile.
Equivalent to specifying ‘-’ before each
command line in the makefile.
- -j
max_jobs
- Specify the maximum number of jobs that
make may have running at any one time. Turns
compatibility mode off, unless the -B flag is also
specified.
- -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 the system
makefile and makefiles included via the <...> style. Multiple
-m options can be specified to form a search path. This
path will override the default system include path,
/usr/share/mk. The system include path will always be
appended to the search path used for "..."-style inclusions and
makefile searches (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 filesystem. 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). Note that a -C that are earlier on the
command line affect where -m “.../”
searches.
- -n
- Display the commands that would have been executed, but do
not actually execute them.
- -P
- Collate the output of a given job and display it only when
the job finishes, instead of mixing the output of parallel jobs together.
This option has no effect unless -j is used too.
- -p
- Only print the input graph, not executing any commands. The
output is the same as -d g1. When
combined with -f /dev/null, only the
builtin rules of make are displayed.
- -Q
- Be extra quiet. For multi-job makes, this will cause file
banners not to be generated.
- -q
- Do not execute any commands, but exit 0 if the specified
targets are up-to-date and 1, otherwise.
- -r
- Do not process the system makefile.
- -S
- Stop processing when an error is encountered. Default
behaviour. This is needed to negate the -k option during
recursive builds.
- -s
- Do not echo any commands as they are executed. Equivalent
to specifying ‘@’ before each command line
in the makefile.
- -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 make's idea of the value of
variable, in the global context. 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.
- -v
- Be extra verbose. Print any extra information.
- -X
- When using the -V option to print the
values of variables, do not recursively expand the values.
- variable=value
- Set the value of the variable
variable to value.
- -x
warning_options
- Specify extended warning options. This option may be
specified several times. A warning_option can be
prefixed with “
no
” in which case the
warning is switched off. The currently available options are:
dirsyntax
- Warn if anything except blanks and comments follows an
.endif or .else directive.
See also the .WARN special target.
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 expressions
‘
?
’,
‘
*
’,
‘
[]
’ and
‘
{}
’. The expressions
‘
?
’,
‘
*
’ 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 expression ‘
{}
’ 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 a series of shell commands, normally
used to create the target. Each of the commands in this script
must be preceded by a tab. While any target may appear on a
dependency line, only one of these dependencies may be followed by a creation
script, unless the ‘
::’ operator is used.
If the first characters of the command line are
‘
@’, ‘
-’, and/or
‘
+’, the command is treated specially. A
‘
@’ causes the command not to be echoed before
it is executed. A ‘
-’ causes any non-zero exit
status of the command line to be ignored. A ‘
+’
causes the command to be executed even if
-n is specified on
the command line.
VARIABLE ASSIGNMENTS¶
Variables in
make are much like variables in the shell, and,
by tradition, consist of all upper-case letters. 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.
- !=
- 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 whitespace 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.
Variable substitution occurs at two 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.
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 and variables
obtained from the
MAKEFLAGS
environment variable
or the .MAKEFLAGS target.
- Local variables
- Variables that are defined specific to a certain
target.
If the name of an environment variable appears in a makefile on the left-hand
side of an assignment, a global variable with the same name is created, and
the latter shadows the former as per their relative precedences. The
environment is not changed in this case, and the change is not exported to
programs executed by
make. However, a command-line variable
actually replaces the environment variable of the same name if the latter
exists, which is visible to child programs.
There are seven local variables in
make:
- .ALLSRC
- The list of all sources for this target; also known as
‘>’.
- .ARCHIVE
- The name of the archive file; also known as
‘!’.
- .IMPSRC
- The name/path of the source from which the target is to be
transformed (the “implied” source); also known as
‘<’.
- .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 file, containing only the file
portion, no suffix or preceding directory components; also known as
‘*’.
- .TARGET
- The name of the target; also known as
‘@’.
The shorter forms ‘
@’,
‘
!’,
‘
<’,
‘
%’, ‘
?’,
‘
>’, and
‘
*’ are permitted for backward compatibility
and are not recommended. The six variables
‘
@F’,
‘
@D’,
‘
<F’,
‘
<D’,
‘
*F’, and
‘
*D’ are permitted for compatibility with
AT&T System V UNIX makefiles and 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.
In addition,
make sets or knows about the following internal
variables or environment variables:
- $
- A single dollar sign
‘
$
’, i.e.
‘$$
’ expands to a single dollar
sign.
- MAKE
- The name that make was executed with
(argv[0]).
- .CURDIR
- A path to the directory where make was
executed. The make utility sets
.CURDIR to the canonical path given by
getcwd(3).
- .OBJDIR
- A path to the directory where the targets are built. At
startup, make searches for an alternate directory to
place target files. It will attempt to change into this special directory
and will search this directory for makefiles not found in the current
directory. The following directories are tried in order:
- ${MAKEOBJDIRPREFIX}/`pwd`
- ${MAKEOBJDIR}
- obj.${MACHINE}
- obj
- /usr/obj/`pwd`
The first directory that make successfully changes into is
used. If either MAKEOBJDIRPREFIX
or
MAKEOBJDIR
is set in the environment but
make is unable to change into the corresponding
directory, then the current directory is used without checking the
remainder of the list. If they are undefined and make is
unable to change into any of the remaining three directories, then the
current directory is used. Note, that
MAKEOBJDIRPREFIX
and
MAKEOBJDIR
must be environment variables and
should not be set on make's command line.
The make utility sets .OBJDIR to the
canonical path given by getcwd(3).
- .MAKEFILE_LIST
- As make reads various makefiles,
including the default files and any obtained from the command line and
.include and .sinclude directives,
their names will be automatically appended to the
.MAKEFILE_LIST variable. They are added right before
make begins to parse them, so that the name of the
current makefile is the last word in this variable.
MAKEFLAGS
- The environment variable
MAKEFLAGS
may initially contain anything that may be specified on
make's command line, including -f
option(s). After processing, its contents are stored in the
.MAKEFLAGS global variable, although any
-f options are omitted. Then all options and variable
assignments specified on make's command line, except for
-f, are appended to the .MAKEFLAGS
variable.
Whenever make executes a program, it sets
MAKEFLAGS
in the program's environment to the
current value of the .MAKEFLAGS global variable.
Thus, if MAKEFLAGS
in make's
environment contains any -f options, they will not be
pushed down to child programs automatically. The make
utility effectively filters out -f options from the
environment and command line although it passes the rest of its options
down to sub-makes via MAKEFLAGS
by default.
When passing macro definitions and flag arguments in the
MAKEFLAGS
environment variable, space and tab
characters are quoted by preceding them with a backslash. When reading the
MAKEFLAGS
variable from the environment, all
sequences of a backslash and one of space or tab are replaced just with
their second character without causing a word break. Any other occurrences
of a backslash are retained. Groups of unquoted space, tab and newline
characters cause word breaking.
- .MAKEFLAGS
- Initially, this global variable contains
make's current run-time options from the environment and
command line as described above, under
MAKEFLAGS
.
By modifying the contents of the .MAKEFLAGS global
variable, the makefile can alter the contents of the
MAKEFLAGS
environment variable made available for
all programs which make executes. This includes adding
-f option(s). The current value of
.MAKEFLAGS is just copied verbatim to
MAKEFLAGS
in the environment of child programs.
Note that any options entered to .MAKEFLAGS neither
affect the current instance of make nor show up in its
own copy of MAKEFLAGS
instantly. However, they do
show up in the MAKEFLAGS
environment variable of
programs executed by make. On the other hand, a direct
assignment to MAKEFLAGS
neither affects the
current instance of make nor is passed down to
make's children. Compare with the
.MAKEFLAGS special target below.
- MFLAGS
- This variable is provided for backward compatibility and
contains all the options from the
MAKEFLAGS
environment variable plus any options specified on
make's command line.
- .MAKE.PID
- The process-id of make.
- .MAKE.PPID
- The parent process-id of make.
- .MAKE.JOB.PREFIX
- If make is run with -j
-v then output for each target is prefixed with a token
‘
--- target ---
’ the first part of
which can be controlled via .MAKE.JOB.PREFIX.
For example:
.MAKE.JOB.PREFIX=${.newline}---${MAKE:T}[${.MAKE.PID}]
would produce tokens like ‘---make[1234] target
---
’ or
.MAKE.JOB.PREFIX=---pid[${.MAKE.PID}],ppid[${.MAKE.PPID}]
would produce tokens like ‘---pid[56789],ppid[1234]
target ---
’ making it easier to track the degree of
parallelism being achieved.
- .TARGETS
- List of targets make is currently
building.
- .INCLUDES
- See .INCLUDES special target.
- .LIBS
- See .LIBS special target.
- MACHINE
- Name of the machine architecture make is
running on, obtained from the
MACHINE
environment
variable, or through uname(3) if not defined.
- MACHINE_ARCH
- Name of the machine architecture make was
compiled for, defined at compilation time.
- VPATH
- Makefiles may assign a colon-delimited list of directories
to VPATH. These directories will be searched for
source files by make after it has finished parsing all
input makefiles.
Variable Modifiers¶
Variable expansion may be modified to select or modify each word of the variable
(where a “word” is whitespace-delimited sequence of characters).
The general format of a variable expansion is as follows:
{variable[:modifier[:...]]}
Each modifier begins with a colon and one of the following special characters.
The colon may be escaped with a backslash
(‘
\
’).
- :C/pattern/replacement/[1g]
- Modify each word of the value, substituting every match of
the extended regular expression pattern (see
re_format(7)) with the ed(1)-style
replacement string. Normally, the first occurrence
of the pattern in each word of the value is changed. 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 as occur in the word or words it is found in. 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.
- :E
- Replaces each word in the variable with its suffix.
- :H
- Replaces each word in the variable with everything but the
last component.
- :L
- Converts variable to lower-case letters.
- :Mpattern
- Select only those words that match the rest of the
modifier. The standard shell wildcard characters
(‘
*
’,
‘?
’, and
‘[]
’) may be used. The wildcard
characters may be escaped with a backslash
(‘\
’).
- :Npattern
- This is identical to :M, but selects all
words which do not match the rest of the modifier.
- :O
- Order every word in the variable alphabetically.
- :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.
- :S/old_string/new_string/[g]
- Modify the first occurrence of
old_string in each word of 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
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. 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.
- :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.
- :T
- Replaces each word in the variable with its last
component.
- :U
- Converts variable to upper-case letters.
- :u
- Remove adjacent duplicate words (like
uniq(1)).
DIRECTIVES,
CONDITIONALS, AND FOR LOOPS¶
Directives, conditionals, 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. The following directives
are supported:
- .include
<file>
-
- .include
"file"
- Include the specified makefile. 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.
- .sinclude
<file>
-
- .sinclude
"file"
- Like .include, but silently ignored if
the file cannot be found and opened.
- .undef
variable
- Un-define the specified global variable. Only global
variables may be un-defined.
- .error
message
- Terminate processing of the makefile immediately. The
filename of the makefile, the line on which the error was encountered and
the specified message are printed to the standard error output and
make terminates with exit code 1. Variables in the
message are expanded.
- .warning
message
- Emit a warning message. The filename of the makefile, the
line on which the warning was encountered, and the specified message are
printed to the standard error output. Variables in the message are
expanded.
Conditionals are used to determine which parts of the Makefile to process. They
are used similarly to the conditionals supported by the C pre-processor. The
following conditionals are supported:
- .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.
An
expression may also be a numeric or string comparison:
in this case, the left-hand side
must be a variable
expansion, whereas the right-hand side can be a constant or a variable
expansion. Variable expansion is performed on both sides, after which the
resulting values are compared. A value is interpreted as hexadecimal if it is
preceded by 0x, otherwise it is decimal; octal numbers are not supported.
String comparison can only use the ‘
==’ or
‘
!=’ operators, whereas numeric values (both
integer and floating point) can also be compared using the
‘
>’, ‘
>=’,
‘
<’ and ‘
<=’
operators.
If no relational operator (and right-hand value) are given, an implicit
‘
!= 0’ is used. However be very careful in using
this feature especially when the left-hand side variable expansion returns a
string.
When
make is evaluating one of these conditional expressions,
and it encounters a word it does not recognize, either the “make”
or “defined” expression is applied to it, depending on the form of
the conditional. If the form is
.if,
.ifdef or
.ifndef, 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 in
expression
-
- <make-rules>
-
- .endfor
-
After the for
expression is evaluated, it is split into
words. The iteration
variable is successively set to
each word, and substituted in the
make-rules inside the body
of the for loop.
Comments begin with a hash (‘
#
’) character,
anywhere but in a shell command line, and continue to the end of the line.
SPECIAL SOURCES¶
- .IGNORE
- Ignore any errors from the commands associated with this
target, exactly as if they all were preceded by a dash
(‘
-
’).
- .MAKE
- Execute the commands associated with this target even if
the -n or -t options were specified.
Normally used to mark recursive make's.
- .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 cannot figure out how to create it, it will ignore
this fact and assume the file is not needed or already exists.
- .PRECIOUS
- When make is interrupted, it removes any
partially made targets. This source prevents the target from being
removed.
- .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.
- .WAIT
- If special .WAIT source appears in a
dependency line, the sources that precede it are made before the sources
that succeed it in the line. Loops are not being detected and targets that
form loops will be silently ignored.
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 cannot
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.
- .END
- Any command lines attached to this target are executed
after everything else is done.
- .IGNORE
- Mark each of the sources with the .IGNORE
attribute. If no sources are specified, this is the equivalent of
specifying the -i option.
- .INCLUDES
- A list of suffixes that indicate files that can be included
in a source file. The suffix must have already been declared with
.SUFFIXES; any suffix so declared will have the
directories on its search path (see .PATH) placed in the
.INCLUDES special variable, each preceded by a
-I flag.
- .INTERRUPT
- If make is interrupted, the commands for
this target will be executed.
- .LIBS
- This does for libraries what .INCLUDES
does for include files, except that the flag used is
-L.
- .MAIN
- If no target is specified when make is
invoked, this target will be built. This is always set, either explicitly,
or implicitly when make selects the default target, to
give the user a way to refer to the default target on the command
line.
- .MAKEFILEDEPS
- Enable the “Remaking Makefiles” functionality,
as explained in the REMAKING
MAKEFILES section below.
- .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. Flags (except for -f) and variable assignments
specified as the source for this target are also appended to the
.MAKEFLAGS internal variable. Please note the
difference between this target and the .MAKEFLAGS
internal variable: specifying an option or variable assignment as the
source for this target will affect both the current
makefile and all processes that make executes.
- .MFLAGS
- Same as above, for backward compatibility.
- .NOTPARALLEL
- Disable parallel mode.
- .NO_PARALLEL
- Same as above, for compatibility with other
pmake variants.
- .ORDER
- The named targets are made in sequence.
- .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. Where possible, use of
.PATH is preferred over use of the
VPATH variable.
- .PATHsuffix
- The sources are directories which are to be searched for
suffixed files not found in the current directory. The
make utility first searches the suffixed search path,
before reverting to the default path if the file is not found there. This
form is required for .LIBS and
.INCLUDES to work.
- .PHONY
- Apply the .PHONY attribute to any
specified sources. Targets with this attribute are always considered to be
out of date.
- .POSIX
- Adjust make's behavior to match the
applicable POSIX specifications. (Note this disables the “Remaking
Makefiles” feature.)
- .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
- Select another shell. The sources of this target have the
format key=value. The
key is one of:
- path
- Specify the path to the new shell.
- name
- Specify the name of the new shell. This may be either
one of the three builtin shells (see below) or any other name.
- quiet
- Specify the shell command to turn echoing off.
- echo
- Specify the shell command to turn echoing on.
- filter
- Usually shells print the echo off command before
turning echoing off. This is the exact string that will be printed by
the shell and is used to filter the shell output to remove the echo
off command.
- echoFlag
- The shell option that turns echoing on.
- errFlag
- The shell option to turn on error checking. If error
checking is on, the shell should exit if a command returns a non-zero
status.
- hasErrCtl
- True if the shell has error control.
- check
- If hasErrCtl is true then this is
the shell command to turn error checking on. If
hasErrCtl is false then this is a command
template to echo commands for which error checking is disabled. The
template must contain a ‘
%s
’.
- ignore
- If hasErrCtl is true, this is the
shell command to turn error checking off. If
hasErrCtl is false, this is a command template
to execute a command so that errors are ignored. The template must
contain a ‘
%s
’.
- meta
- This is a string of meta characters of the shell.
- builtins
- This is a string holding all the shell's builtin
commands separated by blanks. The meta and
builtins strings are used in compat mode. When a
command line contains neither a meta character nor starts with a shell
builtin, it is executed directly without invoking a shell. When one of
these strings (or both) is empty all commands are executed through a
shell.
- unsetenv
- If true, remove the
ENV
environment variable before executing any command. This is useful for
the Korn-shell (ksh).
Values that are strings must be surrounded by double quotes. Boolean values
are specified as ‘T
’ or
‘Y
’ (in either case) to mean true. Any
other value is taken to mean false.
There are several uses of the .SHELL target:
- Selecting one of the builtin shells. This is done by
just specifying the name of the shell with the
name keyword. It is also possible to modify the
parameters of the builtin shell by just specifying other keywords
(except for path).
- Using another executable for one of the builtin
shells. This is done by specifying the path to the executable with the
path keyword. If the last component is the same
as the name of the builtin shell, no name needs to be specified; if it
is different, the name must be given:
.SHELL: path="/usr/local/bin/sh"
selects the builtin shell “sh
” but
will execute it from /usr/local/bin/sh. Like in the
previous case, it is possible to modify parameters of the builtin
shell by just specifying them.
- Using an entirely different shell. This is done by
specifying all keywords.
The builtin shells are “sh
”,
“csh
” and
“ksh
”. Because
FreeBSD has no ksh in
/bin, it is unwise to specify
name=“ksh
”
without also specifying a path.
- .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.
- .SUFFIXES
- Each source specifies a suffix to make.
If no sources are specified, any previous specified suffixes are
deleted.
- .WARN
- Each source specifies a warning flag as previously
described for the -x command line option. Warning flags
specified on the command line take precedence over flags specified in the
makefile. Also, command line warning flags are pushed to sub-makes through
the
MAKEFLAGS
environment variables so that a
warning flag specified on the command line will influence all sub-makes.
Several flags can be specified on a single .WARN target
by separating them with blanks.
REMAKING MAKEFILES¶
If the special target
.MAKEFILEDEPS exists in the Makefile,
make enables the “Remaking Makefiles” feature.
After reading Makefile and all the files that are included using
.include or
.sinclude directives (source
Makefiles)
make considers each source Makefile as a target
and tries to rebuild it. Both explicit and implicit rules are checked and all
source Makefiles are updated if necessary. If any of the source Makefiles were
rebuilt,
make restarts from clean state.
To prevent infinite loops the following source Makefile targets are ignored:
- :: targets that have no
prerequisites
- ! targets
- targets that have .PHONY or
.EXEC attributes
- targets without prerequisites and without commands
When remaking a source Makefile options
-t (touch target),
-q (query mode), and
-n (no exec) do not
take effect, unless source Makefile is specified explicitly as a target in
make command line.
Additionally, system makefiles and
.depend are not considered
as Makefiles that can be rebuilt.
ENVIRONMENT¶
The
make utility uses the following environment variables, if
they exist:
MACHINE
,
MAKE
,
MAKEFLAGS
,
MAKEOBJDIR
,
MAKEOBJDIRPREFIX
, and
MAKESYSPATH
.
FILES¶
- .depend
- list of dependencies
- Makefile
- list of dependencies
- makefile
- list of dependencies
- obj
- object directory
- sys.mk
- system makefile
- /usr/share/mk
- default system makefile directory
- /usr/share/doc/psd/12.make
- PMake tutorial
- /usr/obj
- default
MAKEOBJDIRPREFIX
directory.
- /etc/make.conf
- default path to make.conf(5)
EXAMPLES¶
List all included makefiles in order visited:
make -V .MAKEFILE_LIST | tr \
\\n
COMPATIBILITY¶
Older versions of
make used
MAKE
instead of
MAKEFLAGS
. This was removed for POSIX
compatibility. The internal variable
MAKE is set to the
same value as
.MAKE; support for this may be removed in
the future.
Most of the more esoteric features of
make should probably be
avoided for greater compatibility.
SEE ALSO¶
mkdep(1),
make.conf(5)
PMake - A Tutorial. in
/usr/share/doc/psd/12.make
HISTORY¶
A
make command appeared in PWB UNIX.
BUGS¶
The determination of
.OBJDIR is contorted to the point of
absurdity.
In the presence of several
.MAIN special targets,
make silently ignores all but the first.
.TARGETS is not set to the default target when
make is invoked without a target name and no
.MAIN special target exists.
The evaluation of
expression in a test is very
simple-minded. Currently, the only form that works is
‘
.if ${VAR} op something
’. For instance,
you should write tests as ‘
.if ${VAR} ==
string
’ not the other way around, which would give you an error.
For loops are expanded before tests, so a fragment such as:
.for ARCH in ${SHARED_ARCHS}
.if ${ARCH} == ${MACHINE}
...
.endif
.endfor
will not work, and should be rewritten as:
.for ARCH in ${SHARED_ARCHS}
.if ${MACHINE} == ${ARCH}
...
.endif
.endfor
The parsing code is broken with respect to handling a semicolon after a colon,
so a fragment like this will fail:
HDRS= foo.h bar.h
all:
.for h in ${HDRS:S;^;${.CURDIR}/;}
...
.endfor
A trailing backslash in a variable value defined on the command line causes the
delimiting space in the
MAKEFLAGS
environment variable
to be preceded by that backslash. That causes a submake to not treat that
space as a word delimiter. Fixing this requires a larger rewrite of the code
handling command line macros and assignments to
.MAKEFLAGS.