MAKE(1) MAKE(1)
NAME
make - maintain collections of programs
SYNOPSIS
make [ -f makefile ] [ option ] ... [ name ] ...
DESCRIPTION
Make executes commands in makefile to update the target
names (usually programs). If no target is specified, the
targets of the first rule in makefile are updated. If no -f
option is present, `makefile' and `Makefile' are tried in
order. If makefile is `-', the standard input is taken.
More than one -f option may appear.
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. The prerequisites are
updated before the target.
The makefile comprises a sequence of rules and macro defini-
tions. The first line of a rule is a blank-separated list
of targets, then a single or double colon, then a list of
prerequisite files terminated by semicolon or newline. Text
following a semicolon, and all following lines that begin
with a tab, are shell commands to be executed to update the
target.
If a name appears as target in more than one single-colon
rule, it depends on all of the prerequisites of those rules,
but only one command sequence may be specified among the
rules. A target in a double-colon rule is updated by the
following command sequence only if it is out of date with
respect to the prerequisites of that rule.
Two special forms of name are recognized. A name like a(b)
means the file named b stored in the archive named a. A name
like a((b)) means the file stored in archive a and contain-
ing the entry point b.
Sharp and newline surround comments.
In this makefile `pgm' depends on two files `a.o' and `b.o',
and they in turn depend on `.c' files and a common file
`ab.h':
pgm: a.o b.o
cc a.o b.o -lplot -o pgm
a.o: ab.h a.c
cc -c a.c
b.o: ab.h b.c
MAKE(1) MAKE(1)
cc -c b.c
Makefile lines of the form
string1 = string2
are macro definitions. Subsequent appearances of $(string1)
are replaced by string2. If string1 is a single character,
the parentheses are optional. Each entry in the environment
(see sh(1)) of the make command is taken as a macro defini-
tion, as are command arguments with embedded equal signs.
A target containing a single `%' introduces a pattern rule,
which controls the making of names that do not occur explic-
itly as targets. The `%' matches an arbitrary string called
the stem: A%B matches any string that begins with A and ends
with B. A `%' in a prerequisite name stands for the stem;
and the special macro `$%' stands for the stem in the con-
struction commands. A name that has no explicit rule is
matched against the target of each pattern rule. The first
pattern rule for which the prerequisites exist specifies
further dependencies.
This pattern rule maintains an object library where all the
C source files share a common include file `defs.h'. The
macro `CFLAGS' sets compiler options.
arch.a(%.o) : %.c defs.h
cc $(CFLAGS) -c $%.c
ar r arch.a $%.o
rm $%.o
A set of default pattern rules is built in, and effectively
follows the user's list of rules. Assuming these rules,
which tell, among other things, how to make `.o' files from
`.c' files, the first example becomes:
pgm: a.o b.o
cc a.o b.o -lplot -o pgm
a.o b.o: ab.h
Here, greatly simplified, is a sample of the built-in rules:
CC = cc
%.o: %.c
$(CC) $(CFLAGS) -c $%.c
%.o: %.f
f77 $(FFLAGS) -c $%.f
% : %.c
$(CC) $(CFLAGS) -o $% $%.c
The first rule says that a name ending in `.o' could be made
MAKE(1) MAKE(1)
if a matching name ending in `.c' were present. The second
states a similar rule for files ending in `.f'. The third
says that an arbitrary name can be made by compiling a file
with that name suffixed by `.c'.
Macros make the builtin pattern rules flexible: CC names the
particular C compiler, CFLAGS gives cc(1) options, FFLAGS
for f77(1), LFLAGS for lex(1), YFLAGS for yacc(1), and
PFLAGS for pascal(1).
An older, now disparaged, means of specifying default rules
is based only on suffixes. 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.
The rule to create a file with suffix s2 that depends on a
similarly named file with suffix s1 is specified as an entry
for the `target' s1s2. Order is significant; the first pos-
sible name for which both a file and a rule exist is
inferred. An old style rule for making optimized `.o' files
from `.c' files is
.c.o: ; cc -c -O -o $@ $*.c
The following two macros are defined for use in any rule:
$($@) full name of target
$($/) target name beginning at the last slash, if any
A number of other special macros are defined automatically
in rules invoked by one of the implicit mechanisms:
$* target name with suffix deleted
$@ full target name
$< list of prerequisites in an implicit rule
$? list of prerequisites that are out of date
$^ list of all prerequisites
The following are included for consistency with System V:
$(@D) directory part of $@ (up to last slash)
$(@F) file name part of $@ (after last slash)
$(*D) directory part of $* (up to last slash)
$(*F) file name part of $* (after last slash)
$(<D) directory part of $< (up to last slash)
$(<F) file name part of $< (after last slash)
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 the makefile, or the first
character of the command is `@'.
Commands returning nonzero status (see intro(1)) cause make
to terminate unless the special target `.IGNORE' is in the
MAKE(1) MAKE(1)
makefile or the command begins with <tab><hyphen>.
Interrupt and quit cause the target to be deleted unless the
target depends on the special name `.PRECIOUS'.
Make includes a rudimentary parallel processing ability. If
the separation string is `:&' or `::&', make can run the
command sequences to create the prerequisites simultane-
ously. If two names are separated by an ampersand on the
right side of a colon, those two may be created in parallel.
Other options:
-i Equivalent to the special entry `.IGNORE:'.
-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.
-n Trace and print, but do not execute the commands needed
to update the targets.
-t Touch, i.e. update the modified date of targets, with-
out executing any commands.
-r Equivalent to an initial special entry `.SUFFIXES:'
with no list.
-s Equivalent to the special entry `.SILENT:'.
-e Environment definitions override conflicting defini-
tions in arguments or in makefiles. Ordinary prece-
dence is argument over makefile over environment.
-o Assume old style default suffix list: .SUFFIXES: .out
.o .c .e .r .f .y .l .s .p
-Pn Permit n command sequences to be done in parallel with
`&'.
FILES
makefile, Makefile
SEE ALSO
sh(1), touch(1), ar(1)
S. I. Feldman Make - A Program for Maintaining Computer Pro-
grams