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make
Here is a summary of the features of GNU make
, for comparison
with and credit to other versions of make
. We consider the
features of make
in 4.2 BSD systems as a baseline. If you are
concerned with writing portable makefiles, you should not use the
features of make
listed here, nor the ones in Missing.
Many features come from the version of make
in System V.
VPATH
variable and its special meaning. See Searching Directories for Prerequisites. This feature exists in System V make
, but is undocumented. It is documented in 4.3 BSD make
(which says it mimics System V’s VPATH
feature).MAKEFLAGS
to recursive invocations of make
. See Communicating Options to a Sub-make
.$%
is set to the member name in an archive reference. See Automatic Variables.[email protected]
, $*
, $<
, $%
, and $?
have corresponding forms like $(@F)
and $(@D)
. We have generalized this to $^
as an obvious extension. See Automatic Variables.-b
’ and ‘-m
’, accepted and ignored. In System V make
, these options actually do something.make
via the variable MAKE
even if ‘-n
’, ‘-q
’ or ‘-t
’ is specified. See Recursive Use of make
..a
’ in suffix rules. See Archive Suffix Rules. This feature is obsolete in GNU make
, because the general feature of rule chaining (see Chains of Implicit Rules) allows one pattern rule for installing members in an archive (see Archive Update) to be sufficient.The following features were inspired by various other versions of
make
. In some cases it is unclear exactly which versions inspired
which others.
%
’. This has been implemented in several versions of make
. We’re not sure who invented it first, but it’s been spread around a bit. See Defining and Redefining Pattern Rules.make
for AT&T Eighth Edition Research Unix, and later by Andrew Hume of AT&T Bell Labs in his mk
program (where he terms it “transitive closure”). We do not really know if we got this from either of them or thought it up ourselves at the same time. See Chains of Implicit Rules.$^
containing a list of all prerequisites of the current target. We did not invent this, but we have no idea who did. See Automatic Variables. The automatic variable $+
is a simple extension of $^
.-W
’ in GNU make
) was (as far as we know) invented by Andrew Hume in mk
. See Instead of Executing Recipes.make
and similar programs, though not in the System V or BSD implementations. See Recipe Execution.make
by the patsubst
function before the alternate syntax was implemented for compatibility with SunOS 4. It is not altogether clear who inspired whom, since GNU make
had patsubst
before SunOS 4 was released.+
’ characters preceding recipe lines (see Instead of Executing Recipes) is mandated by IEEE Standard 1003.2-1992 (POSIX.2).+=
’ syntax to append to the value of a variable comes from SunOS 4 make
. See Appending More Text to Variables.archive(mem1 mem2…)
’ to list multiple members in a single archive file comes from SunOS 4 make
. See Archive Members.-include
directive to include makefiles with no error for a nonexistent file comes from SunOS 4 make
. (But note that SunOS 4 make
does not allow multiple makefiles to be specified in one -include
directive.) The same feature appears with the name sinclude
in SGI make
and perhaps others.!=
shell assignment operator exists in many BSD of make
and is purposefully implemented here to behave identically to those implementations.make
’s integration of GNU Guile.The remaining features are inventions new in GNU make
:
-v
’ or ‘--version
’ option to print version and
copyright information.-h
’ or ‘--help
’ option to summarize the options to
make
.MAKE
to recursive make
invocations.
See Recursive Use of make
.-C
’ or ‘--directory
’ command option to change
directory. See Summary of Options.define
.
See Defining Multi-Line Variables.Declare phony targets with the special target .PHONY
.
Andrew Hume of AT&T Bell Labs implemented a similar feature with a
different syntax in his mk
program. This seems to be a case of
parallel discovery. See Phony Targets.
-o
’ or ‘--old-file
’
option to pretend a file’s modification-time is old.
See Avoiding Recompilation of Some Files.Conditional execution.
This feature has been implemented numerous times in various versions
of make
; it seems a natural extension derived from the features
of the C preprocessor and similar macro languages and is not a
revolutionary concept. See Conditional Parts of Makefiles.
MAKEFILES
../
’ from file names, so that
./file
and file
are considered to be the
same file.-lname
’.
See Directory Search for Link Libraries.make
, they must begin with
‘.
’ and not contain any ‘/
’ characters.make
recursion using the
variable MAKELEVEL
. See Recursive Use of make
.MAKECMDGOALS
. See Arguments to Specify the Goals.vpath
search.
See Searching Directories for Prerequisites.make
has a very, very limited form of this
functionality in that it will check out SCCS files for makefiles.make
.
See Loading Dynamic Objects.Next: Missing, Previous: Integrating make, Up: Top [Contents][Index]