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Here is a summary of the features of GNU
make, for comparison
with and credit to other versions of
make. We consider the
make in 4.2 BSD systems as a baseline. If you are
concerned with writing portable makefiles, you should not use the
make listed here, nor the ones in 13. Incompatibilities and Missing Features.
Many features come from the version of
make in System V.
VPATHvariable and its special meaning. See section 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
MAKEFLAGSto recursive invocations of
make. See section Communicating Options to a Sub-
$%is set to the member name in an archive reference. See section Automatic Variables.
$?have corresponding forms like
$(@D). We have generalized this to
$^as an obvious extension. See section Automatic Variables.
make, these options actually do something.
makevia the variable
MAKEeven if `-n', `-q' or `-t' is specified. See section Recursive Use of
make, because the general feature of rule chaining (see section Chains of Implicit Rules) allows one pattern rule for installing members in an archive (see section 11.2 Implicit Rule for Archive Member Targets) to be sufficient.
The following features were inspired by various other versions of
make. In some cases it is unclear exactly which versions inspired
make. We're not sure who invented it first, but it's been spread around a bit. See section Defining and Redefining Pattern Rules.
makefor AT&T Eighth Edition Research Unix, and later by Andrew Hume of AT&T Bell Labs in his
mkprogram (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 section 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 section Automatic Variables. The automatic variable
$+is a simple extension of
make) was (as far as we know) invented by Andrew Hume in
mk. See section Instead of Executing the Commands.
makeand similar programs, though not in the System V or BSD implementations. See section Command Execution.
patsubstfunction before the alternate syntax was implemented for compatibility with SunOS 4. It is not altogether clear who inspired whom, since GNU
patsubstbefore SunOS 4 was released.
make. See section Appending More Text to Variables.
make. See section 11.1 Archive Members as Targets.
-includedirective to include makefiles with no error for a nonexistent file comes from SunOS 4
make. (But note that SunOS 4
makedoes not allow multiple makefiles to be specified in one
-includedirective.) The same feature appears with the name
makeand perhaps others.
The remaining features are inventions new in GNU
makeinvocations. See section Recursive Use of
define. See section Defining Variables Verbatim.
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 section Phony Targets.
This feature has been implemented numerous times in various versions
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 section Conditional Parts of Makefiles.
make, they must begin with `.' and not contain any `/' characters.
makerecursion using the variable
MAKELEVEL. See section Recursive Use of
MAKECMDGOALS. See section Arguments to Specify the Goals.
vpathsearch. See section Searching Directories for Prerequisites.
makehas a very, very limited form of this functionality in that it will check out SCCS files for makefiles.
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