term% cat index.txt MAKE(1) General Commands Manual MAKE(1)
NAME
make - maintain program groups
SYNOPSIS
make [ -f makefile ] [ option ] ... file ...
DESCRIPTION
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
not exist.
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
‘incl'.
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 re‐
placed by string2. If string1 is a single character, the parentheses
are optional.
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are out of date.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 de‐
pends on the special name ‘.PRECIOUS'.
Other options:
-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
current entry.
-n Trace and print, but do not execute the commands needed to up‐
date 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
list.
-s Equivalent to the special entry ‘.SILENT:'.
FILES
makefile, Makefile
SEE ALSO
sh(1), touch(1)
S. I. Feldman Make - A Program for Maintaining Computer Programs
BUGS
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.
MAKE(1)