path: root/usr.bin/make/make.1

.\"	$OpenBSD: make.1,v 1.54 2003/07/14 12:29:22 jmc Exp $
.\"	$OpenPackages$
.\"	$NetBSD: make.1,v 1.18 1997/03/10 21:19:53 christos Exp $
.\"
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.\"    notice, this list of conditions and the following disclaimer in the
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.\"    without specific prior written permission.
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.\"	from: @(#)make.1	8.4 (Berkeley) 3/19/94
.\"
.Dd March 19, 1994
.Dt MAKE 1
.Os
.Sh NAME
.Nm make
.Nd maintain program dependencies
.Sh SYNOPSIS
.Nm make
.Op Fl BPSeiknqrst
.Op Fl D Ar variable
.Op Fl d Ar flags
.Op Fl f Ar makefile
.Op Fl I Ar directory
.Op Fl j Ar max_jobs
.Op Fl m Ar directory
.Op Fl V Ar variable
.Op Ar variable Ns No = Ns Ar value
.Bk -words
.Op Ar target ...
.Ek
.Sh DESCRIPTION
.Nm
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
.Sq Pa BSDmakefile
exists, it is read for this list of specifications.
If it does not exist, the files
.Sq Pa makefile
and
.Sq Pa Makefile
are tried in order.
If the file
.Sq Pa .depend
exists, it is read in addition to the makefile (see
.Xr mkdep 1 ) .
.Pp
The handling of
.Sq Pa BSDmakefile
and
.Sq Pa .depend
are BSD extensions.
.Pp
Standard options are as follows:
.Bl -tag -width Ds
.It Fl e
Specify that environment variables override macro assignments within
makefiles.
.It Fl f Ar makefile
Specify a makefile to read instead of the default
.Sq Pa makefile
and
.Sq Pa Makefile .
If
.Ar makefile
is
.Ql \- ,
standard input is read.
Multiple makefiles may be specified, and are read in the order specified.
.It Fl i
Ignore non-zero exit of shell commands in the makefile.
Equivalent to specifying
.Ql \-
before each command line in the makefile.
.It Fl k
Continue processing after errors are encountered, but only on those targets
that do not depend on the target whose creation caused the error.
.It Fl n
Display the commands that would have been executed, but do not actually
execute them.
.It Fl q
Do not execute any commands, but exit with status 0 if the specified targets
are up-to-date, and 1 otherwise.
.It Fl r
Do not use the built-in rules specified in the system makefile.
.It Fl S
Stop processing when an error is encountered.
This is the default behavior.
This is needed to negate the
.Fl k
option during recursive builds.
.It Fl s
Do not echo commands as they are executed.
Equivalent to specifying
.Sq Ic @
before each command line in the makefile.
.It Fl 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.
.It Ar variable Ns No = Ns Ar value
Set the value of the variable
.Ar variable
to
.Ar value .
.El
.Pp
Extended options are as follows:
.Bl -tag -width Ds
.It Fl 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
.Fl j
is used.
.It Fl D Ar variable
Define
.Ar variable
to be 1.
.It Fl d Ar flags
Turn on debugging, and specify which portions of
.Nm
are to print debugging information.
.Ar flags
is one or more of the following:
.Bl -tag -width Ds
.It Ar A
Print all possible debugging information;
equivalent to specifying all of the debugging flags.
.It Ar a
Print debugging information about archive searching and caching.
.It Ar c
Print debugging information about conditional evaluation.
.It Ar d
Print debugging information about directory searching and caching.
.It Ar f
Print debugging information about the expansion of for loops.
.It Ar "g1"
Print the input graph before making anything.
.It Ar "g2"
Print the input graph after making everything, or before exiting
on error.
.It Ar j
Print debugging information about running multiple shells.
.It Ar l
Print commands in Makefile targets regardless of whether or not they are
prefixed by @.
Also known as loud behavior.
.It Ar m
Print debugging information about making targets, including modification
dates.
.It Ar s
Print debugging information about suffix-transformation rules.
.It Ar t
Print debugging information about target list maintenance.
.It Ar v
Print debugging information about variable assignment.
.El
.It Fl I Ar directory
Specify a directory in which to search for makefiles and included makefiles.
The system makefile directory (or directories, see the
.Fl m
option) is automatically included as part of this list.
.It Fl j Ar max_jobs
Specify the maximum number of jobs that
.Nm
may have running at any one time.
Turns compatibility mode off, unless the
.Ar B
flag is also specified.
.It Fl m Ar directory
Specify a directory in which to search for
.Pa 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:
.Pa /usr/share/mk .
Furthermore, the system include path will be appended to the search path used
for "..."-style inclusions (see the
.Fl I
option).
.It Fl 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
.Fl j
is used too.
.It Fl V Ar variable
Print
.Nm make Ns 's
idea of the value of
.Ar 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.
.El
.Pp
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.
.Pp
In general, lines may be continued from one line to the next by ending
them with a backslash
.Pq Ql \e .
The trailing newline character and initial whitespace on the following
line are compressed into a single space.
.Sh 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
.Dq 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,
.Bd -literal
target1 target2: depa depb
	cmd1
	cmd2
.Ed
is just a short form of
.Bd -literal
target1: depa depb
	cmd1
	cmd2
target2: depa depb
	cmd1
	cmd2
.Ed
.Pp
.Nm
does not support Solaris syntax for true multiple targets:
.Bd -literal
target1 + target2: depa depb
	cmd1
	cmd2
.Ed
.Pp
The operators are as follows:
.Bl -tag -width flag
.It Ic \&:
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
.Nm
is interrupted.
.It Ic \&!
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
.Nm
is interrupted.
.It Ic \&::
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
.Nm
is interrupted.
.El
.Pp
The
.Ic \&::
operator is a fairly standard extension.
The
.Ic \&!
operator is a BSD extension.
.Pp
As an extension, targets and sources may contain the shell wildcard
expressions
.Ql ? ,
.Ql * ,
.Ql []
and
.Ql {} .
The expressions
.Ql ? ,
.Ql *
and
.Ql []
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
.Ql {}
need not necessarily be used to describe existing files.
Expansion is in directory order, not alphabetically as done in the shell.
.Pp
For maximum portability, target names should only consist of periods,
underscores, digits and alphabetic characters.
.Sh 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
.Em 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
.Sq Ic ::
operator is used.
.Pp
If a command line begins with a combination of the characters,
.Sq Ic @ ,
.Sq Ic \-
and/or
.Sq Ic + ,
the command is treated specially.
.Bl -tag -width `@'
.It Sq Ic @
causes the command not to be echoed before it is executed.
.It Sq Ic \-
causes any non-zero exit status of the command line to be ignored.
.It Sq Ic +
causes the command to be executed even if
.Fl n
has been specified (This can be useful to debug recursive Makefiles).
.El
.Pp
The command is always executed using
.Pa /bin/sh
in
.Qq set -e
mode.
.Sh VARIABLE ASSIGNMENTS
Variables in
.Nm
are much like variables in the shell, and, by tradition,
consist of all upper-case letters.
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:
.Bl -tag -width Ds
.It Ic \&=
Assign the value to the variable.
Any previous value is overridden.
.It Ic \&:=
Assign with expansion, i.e., expand the value before assigning it
to the variable (extension)
.It Ic \&+=
Append the value to the current value of the variable (extension).
.It Ic \&?=
Assign the value to the variable if it is not already defined (BSD
extension).
Normally, expansion is not done until the variable is referenced.
.It Ic \&!=
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).
.El
.Pp
Any whitespace before the assigned
.Ar 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.
.Pp
Variables are expanded by surrounding the variable name with either
curly braces
.Pq Ql {}
or parentheses
.Pq Ql ()
and preceding it with
a dollar sign
.Pq Ql \&$ .
If the variable name contains only a single letter, the surrounding
braces or parentheses are not required.
This shorter form is not recommended.
.Pp
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.
.Pp
The four different classes of variables (in order of increasing precedence)
are:
.Bl -tag -width Ds
.It Environment variables
Variables defined as part of
.Nm make Ns 's
environment.
.It Global variables
Variables defined in the makefile or in included makefiles.
.It Command line variables
Variables defined as part of the command line.
.It Local variables
Variables that are defined specific to a certain target.
Standard local variables are as follows:
.Bl -tag -width ".ARCHIVE"
.It Va @
The name of the target.
.It Va \&%
The name of the archive member (only valid for library rules).
.It Va \&!
The name of the archive file (only valid for library rules).
.It Va \&?
The list of prerequisites for this target that were deemed out-of-date.
.It Va \&<
The name of the source from which this target is to be built, if a valid
implied rule (suffix rule) is in scope.
.It Va *
The file prefix of the file, containing only the file portion,
no suffix or preceding directory components.
.El
.Pp
The six variables
.Sq Va "@F" ,
.Sq Va "@D" ,
.Sq Va "<F" ,
.Sq Va "<D" ,
.Sq Va "*F" ,
and
.Sq Va "*D"
yield the
.Qq filename
and
.Qq directory
parts of the corresponding macros.
.Pp
For maximum compatibility,
.Sq Va \&<
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
.Bd -literal
\&.SUFFIXES: .c.o
file.o: file.c
	cmd1 $<

\&.c.o:
	cmd2
.Ed
building
.Pa file.o
will execute
.Qq cmd1 file.c .
.Pp
As an extension,
.Nm
supports the following local variables:
.Bl -tag -width ".ARCHIVE"
.It Va \&>
The list of all sources for this target.
.It Va .ALLSRC
Synonym for
.Sq Va \&> .
.It Va .ARCHIVE
Synonym for
.Sq Va \&! .
.It Va .IMPSRC
Synonym for
.Sq Va \&< .
.It Va .MEMBER
Synonym for
.Sq Va \&% .
.It Va .OODATE
Synonym for
.Sq Va \&? .
.It Va .PREFIX
Synonym for
.Sq Va * .
.It Va .TARGET
Synonym for
.Sq Va @ .
.El
.Pp
These variables may be used on the dependency half of dependency
lines, when they make sense.
.El
.Pp
In addition,
.Nm
sets or knows about the following internal variables, or environment
variables:
.Bl -tag -width MAKEFLAGS
.It Va \&$
A single dollar sign
.Ql \&$ ,
i.e.,
.Ql \&$$
expands to a single dollar
sign.
.It Va .MAKE
The name that
.Nm
was executed with
.Pq Va argv Ns Op 0 .
.It Va .CURDIR
A path to the directory where
.Nm
was executed.
.It Va .OBJDIR
A path to the directory where the targets are built.
At startup,
.Nm
searches for an alternate directory to place target files -- it
will attempt to change into this special directory.
First, if
.Ev MAKEOBJDIRPREFIX
is defined,
.Nm
prepends its contents to the current directory name and tries for
the resulting directory.
If that fails,
.Nm
remains in the current directory.
If
.Ev MAKEOBJDIRPREFIX
is not defined,
.Nm
checks
.Ev MAKEOBJDIR
and tries to change into that directory.
Should that fail,
.Nm
remains in the current directory.
If
.Ev MAKEOBJDIR
is not defined, it tries to change into the directory named
.Pa obj.${MACHINE}
(see
.Va MACHINE
variable).
If it still has found no special directory,
.Nm
next tries the directory named
.Pa obj .
If this fails,
.Nm
tries to prepend
.Pa /usr/obj
to the current directory name.
Finally, if none of these directories are available
.Nm
will settle for and use the current directory.
.It Va .MAKEFLAGS
The environment variable
.Ev MAKEFLAGS
may contain anything that
may be specified on
.Nm make Ns 's
command line.
Its contents are stored in
.Nm make Ns 's
.Va .MAKEFLAGS
variable.
Anything specified on
.Nm make Ns 's
command line is appended to the
.Va .MAKEFLAGS
variable which is then
entered into the environment as
.Ev MAKEFLAGS
for all programs which
.Nm
executes.
.It Va MFLAGS
A shorter synonym for
.Va .MAKEFLAGS .
.It Ev PWD
Alternate path to the current directory.
.Nm
normally sets
.Sq Va .CURDIR
to the canonical path given by
.Xr getcwd 3 .
However, if the environment variable
.Ev PWD
is set and gives a path to the current directory, then
.Nm
sets
.Sq Va .CURDIR
to the value of
.Ev PWD
instead.
.Ev PWD
is always set to the value of
.Sq Va .OBJDIR
for all programs which
.Nm
executes.
.It Va .TARGETS
List of targets
.Nm
is currently building.
.It Va .INCLUDES
See
.Ic .INCLUDES
special target
.It Va .LIBS
See
.Ic .LIBS
special target
.It Va MACHINE
Name of the machine architecture
.Nm
is running on, obtained from the
.Ev MACHINE
environment variable, or through
.Xr uname 3
if not defined.
.It Va MACHINE_ARCH
Name of the machine architecture
.Nm
was compiled for, obtained from the
.Ev MACHINE_ARCH
environment variable, or defined at compilation time.
.El
.Pp
Variable expansion may be modified to select or modify each word of the
variable (where
.Dq word
is a whitespace delimited sequence of characters).
The general format of a variable expansion is as follows:
.Pp
.Dl {variable[:modifier[:...]]}
.Pp
Each modifier begins with a colon and one of the following
special characters.
The colon may be escaped with a backslash
.Pq Ql \e .
.Bl -tag -width Ds
.It Cm E
Replaces each word in the variable with its suffix.
.It Cm H
Replaces each word in the variable with everything but the last component.
.It Cm L
Replaces each word in the variable with its lower case equivalent.
.It Cm U
Replaces each word in the variable with its upper case equivalent.
.It Cm M Ns Ar pattern
Select only those words that match the rest of the modifier.
The standard shell wildcard characters
.Pf ( Ql * ,
.Ql ? ,
and
.Ql [] )
may
be used.
The wildcard characters may be escaped with a backslash
.Pq Ql \e .
.It Cm N Ns Ar pattern
This is identical to
.Cm M ,
but selects all words which do not match
the rest of the modifier.
.It Cm Q
Quotes every shell meta-character in the variable, so that it can be passed
safely through recursive invocations of
.Nm make .
.It Cm R
Replaces each word in the variable with everything but its suffix.
.Sm off
.It Cm S No \&/ Ar old_string Xo
.No \&/ Ar new_string
.No \&/ Op Cm 1g
.Xc
.Sm on
Modify the first occurrence of
.Ar old_string
in the variable's value, replacing it with
.Ar new_string .
If a
.Ql g
is appended to the last slash of the pattern, all occurrences
in each word are replaced.
If a
.Ql 1
is appended to the last slash of the pattern, only the first word
is affected.
If
.Ar old_string
begins with a caret
.Pq Ql ^ ,
.Ar old_string
is anchored at the beginning of each word.
If
.Ar old_string
ends with a dollar sign
.Pq Ql \&$ ,
it is anchored at the end of each word.
Inside
.Ar new_string ,
an ampersand
.Pq Ql &
is replaced by
.Ar old_string
(without any
.Ql ^
or
.Ql \&$ ) .
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
.Pq Ql \e .
.Pp
Variable expansion occurs in the normal fashion inside both
.Ar old_string
and
.Ar new_string
with the single exception that a backslash is used to prevent the expansion
of a dollar sign
.Pq Ql \&$ ,
not a preceding dollar sign as is usual.
.Sm off
.It Cm C No \&/ Ar pattern Xo
.No \&/ Ar replacement
.No \&/ Op Cm 1g
.Xc
.Sm on
The
.Cm C
modifier is just like the
.Cm S
modifier except that the old and new strings, instead of being
simple strings, are a regular expression (see
.Xr regex 3 )
and an
.Xr ed 1 Ns \-style
replacement string.
Normally, the first occurrence of the pattern in
each word of the value is changed.
The
.Ql 1
modifier causes the substitution to apply to at most one word; the
.Ql 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
.Ql 1
and
.Ql g
are orthogonal; the former specifies whether multiple words are
potentially affected, the latter whether multiple substitutions can
potentially occur within each affected word.
.It Cm T
Replaces each word in the variable with its last component.
.It Ar old_string Ns No = Ns Ar new_string
This is the
.At V
style variable substitution.
It must be the last modifier specified.
If
.Ar old_string
or
.Ar new_string
do not contain the pattern matching character
.Ar %
then it is assumed that they are
anchored at the end of each word, so only suffixes or entire
words may be replaced.
Otherwise
.Ar %
is the substring of
.Ar old_string
to be replaced in
.Ar new_string .
.El
.Pp
All modifiers are BSD extensions, except for the standard
.At V
style variable substitution.
.Sh INCLUDE STATEMENTS, CONDITIONALS AND FOR LOOPS
Makefile inclusion, conditional structures and for loops reminiscent
of the C programming language are provided in
.Nm make .
All such structures are identified by a line beginning with a single
dot
.Pq Ql \&.
character.
Whitespace characters may follow this dot, e.g.,
.Bd -literal
    \&.include <file>
.Ed
and
.Bd -literal
    \&.   include <file>
.Ed
are identical constructs.
Files are included with either
.Ql .include <file>
or
.Ql .include \*qfile\*q .
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
.Fl I
option are searched before the system
makefile directory.
.Pp
Conditional expressions are also preceded by a single dot as the first
character of a line.
The possible conditionals are as follows:
.Bl -tag -width Ds
.It Ic .undef Ar variable
Un-define the specified global variable.
Only global variables may be un-defined.
.It Xo
.Ic \&.if
.Oo \&! Oc Ns Ar expression
.Op Ar operator expression ...
.Xc
Test the value of an expression.
.It Xo
.Ic .ifdef
.Oo \&! Oc Ns Ar variable
.Op Ar operator variable ...
.Xc
Test the value of a variable.
.It Xo
.Ic .ifndef
.Oo \&! Oc Ns Ar variable
.Op Ar operator variable ...
.Xc
Test the value of a variable.
.It Xo
.Ic .ifmake
.Oo \&! Oc Ns Ar target
.Op Ar operator target ...
.Xc
Test the target being built.
.It Xo
.Ic .ifnmake
.Oo \&! Oc Ar target
.Op Ar operator target ...
.Xc
Test the target being built.
.It Ic .else
Reverse the sense of the last conditional.
.It Xo
.Ic .elif
.Oo \&! Oc Ar expression
.Op Ar operator expression ...
.Xc
A combination of
.Sq Ic .else
followed by
.Sq Ic .if .
.It Xo
.Ic .elifdef
.Oo \&! Oc Ns Ar variable
.Op Ar operator variable ...
.Xc
A combination of
.Sq Ic .else
followed by
.Sq Ic .ifdef .
.It Xo
.Ic .elifndef
.Oo \&! Oc Ns Ar variable
.Op Ar operator variable ...
.Xc
A combination of
.Sq Ic .else
followed by
.Sq Ic .ifndef .
.It Xo
.Ic .elifmake
.Oo \&! Oc Ns Ar target
.Op Ar operator target ...
.Xc
A combination of
.Sq Ic .else
followed by
.Sq Ic .ifmake .
.It Xo
.Ic .elifnmake
.Oo \&! Oc Ns Ar target
.Op Ar operator target ...
.Xc
A combination of
.Sq Ic .else
followed by
.Sq Ic .ifnmake .
.It Ic .endif
End the body of the conditional.
.El
.Pp
The
.Ar operator
may be any one of the following:
.Bl -tag -width "Cm XX"
.It Cm \&|\&|
logical OR
.It Cm \&&&
Logical
.Tn AND ;
of higher precedence than
.Dq \&|\&| .
.El
.Pp
As in C,
.Nm
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
.Sq Ic \&!
may be used to logically negate an entire
conditional.
It is of higher precedence than
.Sq Ic \&&& .
.Pp
The value of
.Ar expression
may be any of the following:
.Bl -tag -width defined
.It Ic defined
Takes a variable name as an argument and evaluates to true if the variable
has been defined.
.It Ic make
Takes a target name as an argument and evaluates to true if the target
was specified as part of
.Nm make Ns 's
command line or was declared the default target (either implicitly or
explicitly, see
.Va .MAIN )
before the line containing the conditional.
.It Ic empty
Takes a variable, with possible modifiers, and evaluates to true if
the expansion of the variable would result in an empty string.
.It Ic 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
.Va .PATH ) .
.It Ic target
Takes a target name as an argument and evaluates to true if the target
has been defined.
.El
.Pp
.Ar 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
.Sq Ic ==
or
.Sq Ic "!="
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.
.Pp
When
.Nm
is evaluating one of these conditional expressions, and it encounters
a word it doesn't recognize, either the
.Dq make
or
.Dq defined
expression is applied to it, depending on the form of the conditional.
If the form is
.Sq Ic .ifdef
or
.Sq Ic .ifndef ,
the
.Dq defined
expression is applied.
Similarly, if the form is
.Sq Ic .ifmake
or
.Sq Ic .ifnmake ,
the
.Dq make
expression is applied.
.Pp
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
.Sq Ic .else
or
.Sq Ic .endif
is found.
.Pp
For loops are typically used to apply a set of rules to a list of files.
The syntax of a for loop is:
.Bd -unfilled -offset indent
.Xo
.Ic .for Ar variable Op Ar variable ...
.Ic in
.Ar expression
.Xc
	<make-rules>
.Ic \&.endfor
.Ed
.Pp
After the for
.Ar expression
is evaluated, it is split into words.
On each iteration of the loop, one word is assigned to each
.Ar variable ,
in order,
and these
.Ar variables
are substituted in the
.Ic 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.
.Pp
Loops and conditional expressions may nest arbitrarily, but
they may not cross include file boundaries.
.Sh COMMENTS
Comments begin with a hash
.Pq Ql \&#
character, anywhere but in a shell
command line, and continue to the end of the line.
.Sh SPECIAL SOURCES
.Bl -tag -width ".PRECIOUS"
.It Ic .IGNORE
Ignore any errors from the commands associated with this target, exactly
as if they all were preceded by a dash
.Pq Ql \- .
.It Ic .MADE
Mark all sources of this target as being up-to-date.
.It Ic .MAKE
Execute the commands associated with this target even if the
.Fl n
or
.Fl t
options were specified.
Normally used to mark recursive
.Nm make Ns 's .
.It Ic .NOTMAIN
Normally
.Nm
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.
.It Ic .OPTIONAL
If a target is marked with this attribute and
.Nm
can't figure out how to create it, it will ignore this fact and assume
the file isn't needed or already exists.
.It Ic .PRECIOUS
When
.Nm
is interrupted, it removes any partially made targets.
This source prevents the target from being removed.
.It Ic .SILENT
Do not echo any of the commands associated with this target, exactly
as if they all were preceded by an at sign
.Pq Ql @ .
.It Ic .USE
Turn the target into
.Nm make Ns '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
.Ic .USE )
of the
source.
If the target already has commands, the
.Ic .USE
target's commands are appended
to them.
.It Ic .WAIT
If
.Ic .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.
.El
.Sh "SPECIAL TARGETS"
Special targets may not be included with other targets, i.e., they must be
the only target specified.
.Bl -tag -width ".NOTPARALLEL"
.It Ic .BEGIN
Any command lines attached to this target are executed before anything
else is done.
.It Ic .DEFAULT
This is sort of a
.Ic .USE
rule for any target (that was used only as a
source) that
.Nm
can't figure out any other way to create.
Only the shell script is used.
The
.Ic .IMPSRC
variable of a target that inherits
.Ic .DEFAULT Ns 's
commands is set
to the target's own name.
.It Ic .END
Any command lines attached to this target are executed after everything
else is done.
.It Ic .IGNORE
Mark each of the sources with the
.Ic .IGNORE
attribute.
If no sources are specified, this is the equivalent of specifying the
.Fl i
option.
.It Ic .INCLUDES
A list of suffixes that indicate files that can be included in a source
file.
The suffix must have already been declared with
.Ic .SUFFIXES ,
any suffix so declared will have the directories in its search path (see
.Ic .PATH )
placed in the
.Va .INCLUDES
special variable, each preceded by a
.Fl I
flag.
.It Ic .INTERRUPT
If
.Nm
is interrupted, the commands for this target will be executed.
.It Ic .LIBS
This does for libraries what
.Ic .INCLUDES
does for include files, except that the flag used is
.Fl L .
.It Ic .MAIN
If no target is specified when
.Nm
is invoked, this target will be built.
This is always set, either
explicitly, or implicitly when
.Nm
selects the default target, to give the user a way to refer to the default
target on the command line.
.It Ic .MAKEFLAGS
This target provides a way to specify flags for
.Nm
when the makefile is used.
The flags are as if typed to the shell, though the
.Fl f
option will have
no effect.
.\" XXX: NOT YET!!!!
.\" .It Ic .NOTPARALLEL
.\" The named targets are executed in non parallel mode. If no targets are
.\" specified, then all targets are executed in non parallel mode.
.It Ic .NOTPARALLEL
Disable parallel mode.
.It Ic .NO_PARALLEL
Same as above, for compatibility with other pmake variants.
.It Ic .ORDER
The named targets are made in sequence.
.\" XXX: NOT YET!!!!
.\" .It Ic .PARALLEL
.\" The named targets are executed in parallel mode. If no targets are
.\" specified, then all targets are executed in parallel mode.
.It Ic .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.
.It Ic .PATH\fIsuffix\fR
The sources are directories which are to be searched for suffixed files
not found in the current directory.
.Nm
first searches the suffixed search path, before reverting to the default
path if the file is not found there.
.It Ic .PHONY
Apply the
.Ic .PHONY
attribute to any specified sources.
Targets with this attribute are always
considered to be out of date.
.It Ic .PRECIOUS
Apply the
.Ic .PRECIOUS
attribute to any specified sources.
If no sources are specified, the
.Ic .PRECIOUS
attribute is applied to every
target in the file.
.It Ic .SILENT
Apply the
.Ic .SILENT
attribute to any specified sources.
If no sources are specified, the
.Ic .SILENT
attribute is applied to every
command in the file.
.It Ic .SUFFIXES
Each source specifies a suffix to
.Nm make .
If no sources are specified, any previously specified suffices are deleted.
.El
.Sh ENVIRONMENT
.Nm
uses the following environment variables, if they exist:
.Ev MACHINE ,
.Ev MACHINE_ARCH ,
.Ev MAKEFLAGS ,
.Ev MAKEOBJDIR ,
.Ev MAKEOBJDIRPREFIX ,
and
.Ev PWD .
.Nm
also ignores and unsets
.Ev CDPATH .
.Sh FILES
.Bl -tag -width /usr/share/mk -compact
.It Pa .depend
list of dependencies
.It Pa BSDmakefile
list of dependencies
.It Pa Makefile
list of dependencies
.It Pa makefile
list of dependencies
.It Pa sys.mk
system makefile
.It Pa /usr/share/mk
system makefile directory
.IT Pa /usr/obj
default
.Ev MAKEOBJDIRPREFIX
directory.
.El
.Sh SEE ALSO
.Xr mkdep 1
.Pp
.Rs
.%T Make \- A Tutorial
.Re
.Sh STANDARDS
.Nm
mostly conforms to the Single Unix Specification, Version 2,
with some noted extensions and a few problems.
.Pp
Older versions of
.Nm
used
.Ev MAKE
instead of
.Ev MAKEFLAGS .
This was removed for POSIX compatibility.
The internal variable
.Va MAKE
is set to the same value as
.Va .MAKE .
Support for this may be removed in the future.
.Pp
Most of the more esoteric features of
.Nm
should probably be avoided for greater compatibility.
.Sh HISTORY
A
.Nm
command appeared in
.At v7 .
.Sh BUGS
The determination of
.Va .OBJDIR
is contorted to the point of absurdity.
.Pp
If the same target is specified several times in normal dependency rules,
.Nm
silently ignores all commands after the first non empty set of commands,
e.g., in
.Bd -literal
a:
	@echo "Executed"
a:
	@echo "Bad luck"
.Ed
.Pp
@echo "Bad luck" will be silently ignored.
.Pp
.Va .TARGETS
is not set to the default target when
.Nm
is invoked without a target name and no
.Ic MAIN
special target exists.
.Pp
The evaluation of
.Ar expression
in a test is very simple-minded.
Currently, the only form that works is
.Ql .if ${VAR} op something \.
For instance, tests should be written as
.Ql .if ${VAR} = "string" ,
not the other way around, which doesn't work.
.Pp
For loops are expanded before tests, so a fragment such as:
.Bd -literal
\&.for TMACHINE in ${SHARED_ARCHS}
\&.if ${TMACHINE} = ${MACHINE}
     ...
\&.endif
\&.endfor
.Ed
.Pp
won't work, and should be rewritten the other way around.
.Pp
When handling pre-BSD 4.4 archives,
.Nm
may erroneously mark archive members as out of date if the archive name
was truncated.
.Pp
The handling of ; and other special characters in tests may be utterly
bogus.
For instance, in
.Bd -literal
\&A=abcd;c.c
\&.if ${A:R} == "abcd;c"
.Ed
.Pp
the test will never match, even though the value is correct.
.Pp
The conditional handler is incredibly lame.
Junk such as
.Bd -literal
\&.if defined anything goes (A)
.Ed
.Pp
will be accepted silently.
.Pp
In a .for loop, only the variable value is used, assignments will be
evaluated later, e.g., in
.Bd -literal
\&.for I in a b c d
I:=${I:S/a/z}
A+=$I
\&.endfor
.Ed
A will evaluate to a b c d after the loop, not z b c d.
.Pp
The
.Ql +
command modificator is ignored in parallel make mode.