make
MAKE(1) OpenBSD Reference Manual MAKE(1)
NAME
make - maintain program dependencies
SYNOPSIS
make [-BeiknPqrSst] [-D variable] [-d flags] [-f makefile] [-I directory]
[-j max_jobs] [-m directory] [-V variable] [NAME=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 the file `BSDmakefile' exists, it is read for
this list of specifications. If it does not exist, the files `makefile'
and `Makefile' are tried in order. If the file `.depend' exists, it is
read in addition to the makefile (see mkdep(1)).
The handling of `BSDmakefile' and `.depend' are BSD extensions.
Standard options are as follows:
-e Specify that environment variables override macro assignments
within makefiles.
-f makefile
Specify a makefile to read instead of the default `makefile' and
`Makefile'. If makefile is `-', standard input is read.
Multiple makefiles may be specified, and are read in the order
specified.
-i Ignore non-zero exit of shell commands in the makefile.
Equivalent to specifying `-' before each command line in the
makefile.
-k Continue processing after errors are encountered, but only on
those targets that do not depend on the target whose creation
caused the error.
-n Display the commands that would have been executed, but do not
actually execute them.
-q Do not execute any commands, but exit with status 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 Stop processing when an error is encountered. This is the
default behavior. This is needed to negate the -k option during
recursive builds.
-s Do not echo 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.
NAME=value
Set the value of the variable NAME to value.
Extended 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. This is turned on by default unless
-j is used.
-D variable
Define variable to be 1.
-d flags
Turn on debugging, and specify which portions of make are to
print debugging information. 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 expansion 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 job tokens showing which output corresponds to what
job.
j Print debugging information about running multiple
shells.
l Print commands in Makefile targets regardless of whether
or not they are prefixed by @. Also known as loud
behavior.
m Print debugging information about making targets,
including modification dates.
n Print debugging information about target names
equivalence computations.
p Help finding concurrency issues for parallel make by
adding some randomization. If RANDOM_ORDER is defined,
targets will be shuffled before being built. If
RANDOM_DELAY is defined, make will wait between 0 and
${RANDOM_DELAY} seconds at the start of each job. A
given random seed can be forced by setting RANDOM_SEED,
but this does not guarantee reproductibility.
s Print debugging information about suffix-transformation
rules.
t Print debugging information about target list
maintenance.
v Print debugging information about variable assignment.
-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.
-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.
-m directory
Specify a directory in which to search for sys.mk and makefiles
included via the <...> style. Multiple directories can be added
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
"..."-style inclusions (see the -I option).
-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.
-V variable
Print make's idea of 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.
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. Of these, include
statements, conditional directives and for loops are extensions.
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. Note that the use of several targets is merely a
shorthand for duplicate rules. Specifically,
target1 target2: depa depb
cmd1
cmd2
is just a short form of
target1: depa depb
cmd1
cmd2
target2: depa depb
cmd1
cmd2
make does not support Solaris syntax for true multiple targets:
target1 + target2: depa depb
cmd1
cmd2
The 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.
The :: operator is a fairly standard extension. The ! operator is a BSD
extension.
As an extension, 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.
For maximum portability, target names should only consist of periods,
underscores, digits and alphabetic characters.
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 a command line begins with a combination of the characters, `@', `-'
and/or `+', the command is treated specially:
`@' causes the command not to be echoed before it is executed.
`-' causes any non-zero exit status of the command line to be ignored.
`+' causes the command to be executed even if -n has been specified.
(This can be useful to debug recursive Makefiles.)
The command is always executed using /bin/sh in "set -e" mode.
VARIABLE ASSIGNMENTS
Variables in make are much like variables in the shell, and, by
tradition, consist of all upper-case letters. They are also called
`macros' in various texts. For portability, only periods, underscores,
digits and letters should be used for variable names. 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.
:= Assign with expansion, i.e., expand the value before assigning it
to the variable (extension).
+= Append the value to the current value of the variable
(extension).
?= Assign the value to the variable if it is not already defined
(BSD extension). 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 (BSD extension).
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.
Local variables
Variables that are defined specific to a certain target.
Standard local variables are as follows:
@ The name of the target.
% The name of the archive member (only valid for library
rules).
! The name of the archive file (only valid for library
rules).
? The list of prerequisites for this target that were
deemed out-of-date.
< The name of the source from which this target is to be
built, if a valid implied rule (suffix rule) is in
scope.
* The file prefix of the file, containing only the file
portion, no suffix or preceding directory components.
The six variables `@F', `@D', `<F', `<D', `*F', and `*D' yield
the "filename" and "directory" parts of the corresponding macros.
For maximum compatibility, `<' should only be used for actual
implied rules. It is also set when there is an implied rule that
matches the current dependency in scope. That is, in
.SUFFIXES: .c .o
file.o: file.c
cmd1 $<
.c.o:
cmd2
building file.o will execute "cmd1 file.c".
As an extension, make supports the following local variables:
> The list of all sources for this target.
.ALLSRC Synonym for `>'.
.ARCHIVE Synonym for `!'.
.IMPSRC Synonym for `<'.
.MEMBER Synonym for `%'.
.OODATE Synonym for `?'.
.PREFIX Synonym for `*'.
.TARGET Synonym for `@'.
These variables may be used on the dependency half of dependency
lines, when they make sense.
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.
.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. First, if MAKEOBJDIRPREFIX is defined, make
prepends its contents to the current directory name and tries
for the resulting directory. If that fails, make remains in
the current directory. If MAKEOBJDIRPREFIX is not defined,
make checks MAKEOBJDIR and tries to change into that
directory. Should that fail, make remains in the current
directory. If MAKEOBJDIR is not defined, it tries to change
into the directory named obj.${MACHINE} (see MACHINE
variable). If it still has found no special directory, make
next tries the directory named obj. If this fails, make tries
to prepend /usr/obj to the current directory name. Finally,
if none of these directories are available make will settle
for and use the current directory.
.MAKEFLAGS
The environment variable MAKEFLAGS may contain anything that
may be specified on make's command line. Its contents are
stored in make's .MAKEFLAGS variable. Anything specified on
make's command line is appended to the .MAKEFLAGS variable
which is then entered into the environment as MAKEFLAGS for
all programs which make executes.
MFLAGS A shorter synonym for .MAKEFLAGS.
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. PWD is always set to the value of `.OBJDIR' for
all programs which make executes.
.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,
obtained from the MACHINE_ARCH environment variable, or
defined at compilation time.
MACHINE_CPU
Name of the machine processor make was compiled for, obtained
from the MACHINE_CPU environment variable, or defined at
compilation time. On processors where only one endianness is
possible, the value of this variable is always the same as
MACHINE_ARCH.
MAKEFILE Possibly the file name of the last makefile that has been
read. It should not be used; see the BUGS section below.
Variable expansion may be modified to select or modify each word of the
variable (where ``word'' is a 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 (`\').
:E Replaces each word in the variable with its suffix.
:H Replaces each word in the variable with everything but the last
component.
:L Replaces each word in the variable with its lower case
equivalent.
:U Replaces each word in the variable with its upper case
equivalent.
: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.
:Q Quotes every shell meta-character in the variable, so that it can
be passed safely through recursive invocations of make.
:QL Quote list: quotes every shell meta-character in the variable,
except whitespace, so that it can be passed to a shell's `for'
loops.
:R Replaces each word in the variable with everything but its
suffix.
:S/old_string/new_string/[1g]
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 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/[1g]
The :C modifier is just like the :S modifier except that the old
and new strings, instead of being simple strings, are a regular
expression (see regex(3)) and an 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.
:T Replaces each word in the variable with its last component.
: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. The right
hand side (new_string) may contain variable values, which will be
expanded. To put an actual single dollar, just double it.
All modifiers are BSD extensions, except for the standard AT&T System V
UNIX style variable substitution.
The interpretation of % and $ in AT&T System V UNIX variable
substitutions is not mandated by POSIX, though it is fairly common.
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.
Whitespace characters may follow this dot, e.g.,
.include <file>
and
. include <file>
are identical constructs. 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.
Conditional expressions are also preceded by a single dot as the first
character of a line. The possible conditionals are as follows:
.undef variable
Un-define the specified global variable. Only global variables
may be un-defined.
.poison variable
Poison the specified global variable. Any further reference to
variable will be flagged as an error.
.poison !defined (variable)
It is an error to try to use the value of variable in a context
where it is not defined.
.poison empty (variable)
It is an error to try to use the value of variable in a context
where it is not defined or empty.
.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.
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.
When make is evaluating one of these conditional expressions, and it
encounters a 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' 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 [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 assigned to each variable, in order,
and these variables are substituted in the make-rules inside the body of
the for loop. The number of words must match the number of iteration
variables; that is, if there are three iteration variables, the number of
words must be a multiple of three.
Loops and conditional expressions may nest arbitrarily, but they may not
cross include file boundaries.
COMMENTS
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 (`-').
.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 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 can't
figure out how to create it, it will ignore this fact and
assume the file isn't 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 .WAIT appears in a dependency line, the sources that
precede it are made before the sources that succeed it in the
line. Loops are not 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 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.
.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 in 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.
.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.
.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.
.PATHsuffix The sources are directories which are to be searched for
suffixed files not found in the current directory. make
first searches the suffixed search path, before reverting
to the default path if the file is not found there.
.PHONY Apply the .PHONY attribute to any specified sources.
Targets with this attribute are always considered to be out
of date.
.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.
.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 previously specified suffixes are deleted.
ENVIRONMENT
make uses the following environment variables, if they exist: MACHINE,
MACHINE_ARCH, MACHINE_CPU, MAKEFLAGS, MAKEOBJDIR, MAKEOBJDIRPREFIX, and
PWD. make also ignores and unsets CDPATH.
FILES
.depend list of dependencies
BSDmakefile default makefile
makefile default makefile if BSDmakefile does not exist
Makefile default makefile if makefile does not exist
sys.mk system makefile
/usr/share/mk system makefile directory
/usr/obj default MAKEOBJDIRPREFIX directory
EXIT STATUS
If -q was specified, the make utility exits with one of the following
values:
0 Normal behavior.
1 The target was not up-to date.
>1 An error occurred.
Otherwise, the make utility exits with a value of 0 on success, and >0 if
an error occurred.
SEE ALSO
ed(1), mkdep(1), sh(1), getcwd(3), regex(3), uname(3)
STANDARDS
The make utility is compliant with the IEEE Std 1003.1-2008 (``POSIX.1'')
specification, though its presence is optional.
The flags [-BDdIjmPV] are extensions to that specification.
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.
HISTORY
A make command appeared in Version 7 AT&T UNIX.
BUGS
The determination of .OBJDIR is contorted to the point of absurdity.
If the same target is specified several times in normal dependency rules,
make silently ignores all commands after the first non empty set of
commands, e.g., in
a:
@echo "Executed"
a:
@echo "Bad luck"
@echo "Bad luck" will be silently ignored.
.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,
tests should be written as `.if ${VAR} == string', not the other way
around, which doesn't work.
For loops are expanded before tests, so a fragment such as:
.for TMACHINE in ${SHARED_ARCHS}
.if ${TMACHINE} == ${MACHINE}
...
.endif
.endfor
won't work, and should be rewritten the other way around.
When handling pre-BSD 4.4 archives, make may erroneously mark archive
members as out of date if the archive name was truncated.
The handling of `;' and other special characters in tests may be utterly
bogus. For instance, in
A=abcd;c.c
.if ${A:R} == "abcd;c"
the test will never match, even though the value is correct.
The conditional handler is incredibly lame. Junk such as
.if defined anything goes (A)
will be accepted silently.
In a .for loop, only the variable value is used; assignments will be
evaluated later, e.g., in
.for I in a b c d
I:=${I:S/a/z}
A+=$I
.endfor
`A' will evaluate to a b c d after the loop, not z b c d.
ORDER is only used in parallel mode, so keep dependency ordered for
sequential mode!
Distinct target names are treated separately, even though they might
correspond to the same file in the file system. This can cause excessive
rebuilds of some targets, and bogus races in parallel mode. This can
also prevent make from finding a rule to solve a dependency if the target
name is not exactly the same as the dependency.
In parallel mode, -j n only limits the number of concurrent makes it
knows about. During recursive invocations, each level will multiply the
number of processes by n.
The MAKEFILE variable cannot be used reliably. It is a compatibility
feature and may get set to the last makefile specified, as it is set by
System V make.
OpenBSD 5.1 May 2, 2011 OpenBSD 5.1
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