MAKE(1) General Commands Manual MAKE(1)
make - maintain program groups
make [ -f makefile ] [ option ] ... file ...
Make executes commands in makefile to update one or more target names.
Name is typically a program. 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
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.
Sharp and newline surround comments.
The following makefile 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
pgm: a.o b.o
cc a.o b.o -lm -o pgm
a.o: incl a.c
cc -c a.c
b.o: incl b.c
cc -c b.c
Makefile entries of the form
string1 = string2
are macro definitions. Subsequent appearances of $(string1) are
replaced by string2. If string1 is a single character, the parentheses
Make infers prerequisites for files for which makefile gives no con-
struction commands. For example, a `.c' file may be inferred as pre-
requisite for a `.o' file and be compiled to produce the `.o' file.
Thus the preceding example can be done more briefly:
pgm: a.o b.o
cc a.o b.o -lm -o pgm
a.o b.o: incl
Prerequisites are inferred according to selected suffixes listed as the
`prerequisites' for the special name `.SUFFIXES'; multiple lists accu-
mulate; 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
.SUFFIXES: .out .o .c .e .r .f .y .l .s
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. In such an entry, the special macro $* stands for the target
name with suffix deleted, $@ for the full target name, $< for the com-
plete 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are out of date.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
.c.o: ; cc -c -O -o $@ $*.c
Certain macros are used by the default inference rules to communicate
optional arguments to any resulting compilations. In particular,
`CFLAGS' is used for cc and f77(1) options, `LFLAGS' and `YFLAGS' for
lex and yacc(1) options.
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 makefile, or the first character of the command is `@'.
Commands returning nonzero status (see intro(1)) cause make to termi-
nate unless the special target `.IGNORE' is in 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'.
-i Equivalent to the special entry `.IGNORE:'.
-k When a command returns nonzero status, abandon work on the cur-
rent entry, but continue on branches that do not depend on the
-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, without execut-
ing any commands.
-r Equivalent to an initial special entry `.SUFFIXES:' with no
-s Equivalent to the special entry `.SILENT:'.
S. I. Feldman Make - A Program for Maintaining Computer Programs
Some commands return nonzero status inappropriately. Use -i to over-
come the difficulty.
Commands that are directly executed by the shell, notably cd(1), are
ineffectual across newlines in make.