.TH MAKE 1
.SH NAME
make \- maintain program groups
.SH SYNTAX
.B make
[
.B \-f
makefile ] [ option ] ...
file ...
.SH DESCRIPTION
.I make
executes commands in
.I makefile
to update
one or more target
.IR names .
.I name
is typically a program.
If no
.B \-f
option is present, \fImakefile\fP and \fPMakefile\fP are
tried in order.
If
.I makefile
is `\-', the standard input is taken.
More than one
.B \-f
option may appear
.PP
.I make
updates a target if it depends on prerequisite files
that have been modified since the target was last modified,
or if the target does not exist.
.PP
.I Makefile
contains a sequence of entries that specify dependencies.
The first line of an entry is a
blank-separated list of targets, then a colon,
then a list of prerequisite files.
Text following a semicolon, and all following lines
that begin with a tab, are shell commands
to be executed to update the target.
.PP
Sharp and newline surround comments.
.PP
The following \fImakefile\fP says that `pgm' depends on two
files `a.o' and `b.o', and that they in turn depend on
`.c' files and a common file `incl':
.RS 
.HP
.PD 0
.nf
pgm: a.o b.o
cc a.o b.o \-lm \-o pgm
.HP
a.o: incl a.c
cc \-c a.c
.HP
b.o: incl b.c
cc \-c b.c
.fi
.RE
.PD
.PP
.I Makefile
entries of the form:
.PP
.IP
string1 = string2
.PP
are macro definitions.
Subsequent appearances of 
.I $(string1)
are replaced by
.IR string2 .
If
.I string1
is a single character, the parentheses are optional.
.PP
.I make 
infers prerequisites for files for which
.I makefile
gives no construction commands.
For example, a
`.c' file may be inferred as prerequisite for a `.o' file
and be compiled to produce the `.o' file.
Thus the preceding example can be done more briefly:
.RS
.HP
.PD 0
.nf
pgm: a.o b.o
cc a.o b.o \-lm \-o pgm
.HP
a.o b.o: incl
.fi
.RE
.PD
.PP
Prerequisites are inferred according to selected suffixes
listed as the `prerequisites' for the special name `.SUFFIXES';
multiple lists accumulate;
an empty list clears what came before.
Order is significant; the first possible name for which both
a file and a rule as described in the next paragraph exist
is inferred.
The default list is:
.IP
\&.SUFFIXES: .out .o .c .e .r .f .y .l .s
.PP
The rule to create a file with suffix
.I s2
that depends on a similarly named file with suffix
.I s1
is specified as an entry
for the `target'
.IR s1s2 .
In such an entry, the special macro $* stands for
the target name with suffix deleted, $@ for the full target name,
$< for the complete list of prerequisites,
and
$? for the list of prerequisites that are out of date.
For example, a rule for making
optimized `.o' files from `.c' files is:
.IP
\&.c.o: ; cc \-c \-O \-o $@ $*.c
.PP
Certain macros are used by the default inference rules
to communicate optional arguments to
any resulting compilations.
In particular, `CFLAGS' is used for \fIcc\fP and \fIf77\fP\|(1)
options, `LFLAGS' and `YFLAGS' for 
\fIlex\fP and \fIyacc\fP\|(1)
options.
.PP
Command lines are executed one at a time, each by its
own shell.
A line is printed when it is executed unless
the special target `.SILENT'
is in 
.I makefile,
or the first character of the command is `@'.
.PP
Commands returning nonzero status (see \fIintro\fP\|(1))
cause
.I make
to terminate unless
the special target `.IGNORE' is in
.I makefile
or the command begins with
<tab><hyphen>.
.PP
Interrupt and quit cause the target to be deleted
unless the special name `.PRECIOUS' depends on the target.
.PP
Other options:
.TP
.B \-\^i
Equivalent to the special entry `.IGNORE:'.
.TP
.B \-\^k
When a command returns nonzero status,
abandon work on the current entry, but
continue on branches that do not depend on the current entry.
.TP
.B \-\^n
Trace and print, but do not execute the commands
needed to update the targets.
.TP
.B \-\^t
Touch, i.e. update the modified date of targets, without
executing any commands.
.TP
.B \-\^r
Equivalent to an initial special entry `.SUFFIXES:'
with no list.
.TP 
.B \-\^s
Equivalent to the special entry
`.SILENT:'.
.SH FILES
makefile, Makefile
.br
.SH "SEE ALSO"
sh(1), touch(1)
.br
S. I. Feldman, 
.I
Make \(em A Program for Maintaining Computer Programs
.SH BUGS
Some commands return nonzero status inappropriately.
Use
.B \-i
to overcome the difficulty.
.br
Commands that are directly executed by the shell,
notably \fIcd\fP\|(1), are ineffectual across newlines in
.I make.
.br
.I Make
is not understanding of libraries or compiler define flags.
.br
Macros are not redefinable in
.I make
command lines.