Referring to https://www.gnu.org/software/make/manual/make.html#Automatic-Variables
$?
The names of all the prerequisites that are newer than the target, with spaces between them. If the target does not exist, all prerequisites will be included. For prerequisites which are archive members, only the named member is used (see Archives).
$^
The names of all the prerequisites, with spaces between them. For prerequisites which are archive members, only the named member is used (see Archives). A target has only one prerequisite on each other file it depends on, no matter how many times each file is listed as a prerequisite. So if you list a prerequisite more than once for a target, the value of $^ contains just one copy of the name. This list does not contain any of the order-only prerequisites; for those see the ‘$|’ variable, below.
The 2 operators look very similar and so I am wondering when they will be different.
Related
I have two directories:
Directory #1, 'C'
C's absolute path:
/A/B/C
Directory #2, 'T'
T's absolute path:
/Q/R/T
I want to use rsync, to copy all files, recursively, from C, and copy them in to T, while maintaining the original directory structure - but only from B onwards.
Example to make it clearer: suppose 'B' has only 3 files nested within it:
/A/B/f1.txt
/A/B/C/f2.txt
/A/B/C/D/f3.txt
Then I want to end up with only f2.txt and f3.txt being copied over, with the final filepaths as follows (notice how I keep the directory structure, only from B onwards):
/Q/R/T/B/C/f2.txt
/Q/R/T/B/C/D/f3.txt
Here is the catch: I must execute the rsync cmd from within /Q/R/. So when I execute this command, my pwd must be /Q/R/.
Can anyone help me figure out how to do this?
[If I did not have this constraint of where my cwd must be, I could cd to /A/B, and then execute: rsync . /Q/R/T/ --recursive --relative . Unfortunately, I can not do that for reasons that would take a lot of pointless explaining here. And when I try to execute rsync /A/. /Q/R/T/ --recursive --relative, I end up with not only everything within A, but maintaining that first part of the dir structure (/A/) that I don't want. (Note - in the real life scenario the dir structure is much more complex then this, this is just the general problem.]
The rsync command includes a couple of options which are suitable for this scenario. They are:
--include=PATTERN - Don't exclude files matching PATTERN
--exclude=PATTERN - Exclude files matching PATTERN
An excellent description and examples of the --exclude flag can be found here.
Solution
Given the directory structures provided in your question and your pwd being set to /Q/R/. Running the following command will meet your requirement:
rsync ../../A/ T/ --recursive --include A/B/** --exclude B/*.*
Edit:
If you do want /A/B/f1.txt to copy to /Q/R/T/B/f1.txt (as it's unclear in your question because you don't show it in the "I want to end up with" example"). Then omit the --exclude B/*.* part, so the complete command is reduced to:
rsync ../../A/ T/ --recursive --include A/B/**
or reduced even further in complexity to just:
rsync ../../A/** T/ --recursive
Explanation of the command
../../A/
The first argument provides the path to the source directory. I.e. The relative position within the hierarchical tree of names (Based on your pwd being /Q/R).
T/
The second argument provides the path to the destination directory. Again this is a relative position within the hierarchical tree of names (and is also based on the pwd being /Q/R).
--recursive
The first option is to recurse into the directories.
--include A/B/**
This says that you want to include all the assets (files/folders), however many levels deep, from within the folder named B which resides inside folder A.
--exclude B/*.*
This says that you want to exclude any assets (files/folders), whose name includes a dot [.] plus extension, which reside inside folder B (at the top level). This will prevent the file named f1.txt from being copied. You could be even more specific here and use --exclude B/f1.txt instead, however I'm assuming in real life you perhaps have additional files you want to exclude here too.
Additional notes
Both the --include and --exclude options can be utilized multiple times. This can be very useful for some scenarios too as it enables you to be specific about what to include and/or exclude during the copy process.
For example, lets assume that your source directory /A/B/, (as described in your question), also contains a folder named X. So its path is A/B/X.
Lets say that we also do not want to copy this folder named X (in the same way as you currently do not want to copy /A/B/f1.txt).
For this scenario we add another --exclude option as follows:
rsync ../../A/ T/ --recursive --include A/B/** --exclude B/*.* --exclude X/
Note the additional --exclude X/ at the end.
You mention...
(Note - in the real life scenario the dir structure is much more complex then this, this is just the general problem.
... in your question, so you may find it necessary to add additional --exclude=PATTERN to truly meet your requirements.
Grunt
As you have included the gruntjs flag with your question, then you may want to consider utilizing plug-ins which can run shell commands like rsync such as:
grunt-shell
grunt-exec
What's the difference between:
ar -x liba.a
ar -x libb.a
ar rcs libab.a *.o
and
ar rcs libab.a liba.a libb.a
Are they really doing the same task?
Unless you're using a version of ar that I don't know about, the effects of the two sequences of commands are quite different — though both end up creating a file libab.a.
The first sequence extracts all the (object) files from liba.a into the current directory, then all the files from libb.a (any name collisions mean the file from libb.a will survive), and then all the object files that are now in the directory (possibly including ones that were in neither liba.a nor libb.a) are archived in libab.a.
The second sequence creates an archive that itself contains two files: liba.a and libb.a. This is legal and feasible, but the resulting file isn't useful in linking programs. The linker doesn't look at nested archives; it will simply find no object files that supply any symbols (since neither liba.a nor libb.a is an object file), so the library will effectively be unused — though you'll not get an error from attempting to use it.
It is more likely that the first sequence of commands is useful than the second.
I am trying to write a recursive make recipe. In this recipe, each target is dependent on a file with an equal name on the parent directory. A minimal (non-working) example:
foo/.dirstamp:
mkdir $(dir $#)
touch $#
.SECONDEXPANSION:
%/.dirstamp: $$(dir $$*).dirstamp
mkdir $(dir $#)
touch $#
With this example, I would expect make foo/bar/qux/lol/.dirstamp to generate the whole directory tree (if it does not exist), touching all .dirstamp files along the way. However, it does not work:
$ ls # note that there is nothing, make is meant to create the dir tree
Makefile
$ make --debug=v foo/bar/qux/lol/.dirstamp
GNU Make 4.0
[...]
Reading makefiles...
Reading makefile 'Makefile'...
Updating goal targets....
Considering target file 'foo/bar/qux/lol/.dirstamp'.
File 'foo/bar/qux/lol/.dirstamp' does not exist.
Finished prerequisites of target file 'foo/bar/qux/lol/.dirstamp'.
Must remake target 'foo/bar/qux/lol/.dirstamp'.
make: *** No rule to make target 'foo/bar/qux/lol/.dirstamp'. Stop.
It works fine as long as the recursive recipe only needs to be expanded twice, e.g., make foo/bar/.dirstamp works fine.
How can this work for an arbitrary number of levels? How can I handle a recursive expansion for the target and prerequisites names?
Note: my real problem is that the prerequisites of my recipes are in a root
directory different from the target so I am using the recipe above to duplicate the directory tree. I know about mkdir -p which seems to work fine in GNU systems. I am still interested on knowing how I would solve the recursion problem for arbitrary levels. which no longer works because part of the team is using Mac and mounting this directories over smb.
More details on the actual problem: prerequisites are in data/x/y/z while targets go into results/x/y/z. However, the results directory tree does not exist and needs to be created as needed. To solve this, I made the creation of parent directories an order-only prerequisite (via the .dirstamp files on my minimal example above).
can't copy data into results, that's several TB of data;
can't have the targets created in data, that's read-only;
can't use mkdir -p because the results directory will not be local, mounted over smb, and others may use non-GNU systems;
After an hint from #EtanReisner on the question:
make won't apply a rule more than once. That's a built-in (intentional) limitation. Without working around that with manual recursion or manually building the set of targets and using a static pattern rule (which may or may not actually work I'm not sure) there's not much you can do about this.
I worked up this solution:
RESULT_DIRS := $(patsubst data/%, results/%, $(shell find data/* -type d -print))
DIRSTAMPS := $(addsuffix /.dirstamp, $(RESULT_DIRS))
results/.dirstamp:
mkdir $(dir $#)
touch $#
.SECONDEXPANSION:
$(DIRSTAMPS): $$(dir $$(patsubst %/.dirstamp, %, $$#)).dirstamp
mkdir $(dir $#)
touch $#
It will duplicate the data directory tree in results as the dirstamp files are required. They are required by making them prerequisites of the other recipes (note the | which makes them order-only prerequisites):
results/%/foo.analysis: data/%/foo.data | results/%/.dirstamp
$(SOME_ANALYSIS_PROGRAM) $^ > $#
Can I write a wrapper makefile that will cd one level up and execute there make with all the command options I have given the wrapper?
In more detail:
Directory project contains a real Makefile with some different targets.
Directory project/resources contains the wrapper Makefile which should call Makefile in project.
When I am in my shell in directory project/resources, I execute
make TARGET
and the Makefile there just cds one directory up and calls
make TARGET
in the directory project.
Is this possible? And how?
You could use a very simple Makefile for all your sub-directories:
%:
$(MAKE) -C .. $#
% is a last resort match-anything pattern rule that will match any target... for which there is no implicit rule (GNU make has an incredibly large number of implicit rules). So, if none of your targets are covered by an implicit rule, this should work. Else you will have to tell make not to use the implicit rules it knows. This can be done (with GNU make) by calling make with the -r option:
cd project/resources
make -r <anything>
will call make in project for target <anything>. The main drawback is that the -r flag is passed to the sub-make and so the implicit rules will not apply neither in project, which can be a problem. If it is you can obtain the same effect by adding an empty .SUFFIXES target to theMakefile in project/resources:
.SUFFIXES:
%:
$(MAKE) -C .. $#
With my version of GNU make (3.82) it works like a charm and the sub-make has all the default implicit rules.
Yes, you can have a makefile which works for "any" target.
The GNU make manual discusses this in the Overriding Part of Another Makefile section:
Sometimes it is useful to have a makefile that is mostly just like another makefile. You can often use the ‘include’ directive to include one in the other, and add more targets or variable definitions. However, it is invalid for two makefiles to give different recipes for the same target. But there is another way.
In the containing makefile (the one that wants to include the other), you can use a match-anything pattern rule to say that to remake any target that cannot be made from the information in the containing makefile, make should look in another makefile. See Pattern Rules, for more information on pattern rules.
For example, if you have a makefile called Makefile that says how to make the target ‘foo’ (and other targets), you can write a makefile called GNUmakefile that contains:
foo:
frobnicate > foo
%: force
#$(MAKE) -f Makefile $#
force: ;
If you say ‘make foo’, make will find GNUmakefile, read it, and see that to make foo, it needs to run the recipe ‘frobnicate > foo’. If you say ‘make bar’, make will find no way to make bar in GNUmakefile, so it will use the recipe from the pattern rule: ‘make -f Makefile bar’. If Makefile provides a rule for updating bar, make will apply the rule. And likewise for any other target that GNUmakefile does not say how to make.
The way this works is that the pattern rule has a pattern of just ‘%’, so it matches any target whatever. The rule specifies a prerequisite force, to guarantee that the recipe will be run even if the target file already exists. We give the force target an empty recipe to prevent make from searching for an implicit rule to build it—otherwise it would apply the same match-anything rule to force itself and create a prerequisite loop!
One option: use a wrapper file to execute the commands to do that. Just be sure your target make files don't include the child directory that has the wrapper, or else you can create an endless loop. For example,
clean:
pushd .. && make clean && popd
Using the comment of user Renaud Pacalet and the answer to a different question the following one-liner is as close as I could get. The whole Makefile reads:
IGNORE := $(shell $(MAKE) -C .. $(MAKECMDGOALS))
This solutions comes with a few caveats:
Command line option -B does not get passed through to the subsequent make call.
The output of the subsequently called make process (in the project directory) is not printed to stdout.
The wrapper make process reports for any given target at the end :
make: *** No rule to make target TARGET. Stop.
I am thinking I may need to use the file function in GNU make, and just can not follow the example they give. I have looked online, but don't see any post with more explanation. Here is the example they give:
program: $(OBJECTS)
$(file >$#.in,$^)
$(CMD) $(CMDFLAGS) #$#.in
#rm $#.in
I think I know what it is doing at a high level as it is explained in the manual.
$#.in
is a list of all the target files
$^
is a list of the source files
I am not sure how #$#.in is used on the third line or what there is an # sign at the beginning. What does that mean please? What does it supposed to do?
The key to the operation of that recipe is given in the prose immediately preceding it in the manual:
Many commands use the convention that an argument prefixed with an # specifies a file containing more arguments. Then you might write your recipe in this way:
program: $(OBJECTS)
$(file >$#.in,$^)
$(CMD) $(CMDFLAGS) #$#.in
#rm $#.in
$# is the target file (there is only one of those in any given recipe)
$#.in is the target file with .in added to the end of the name.
$^ is the "list" of the all the prerequisites of the target.
#$#.in is the name of the target with .in at the end and # at the start.
So the $(file ...) call in that recipe writes the list of prerequisites of the target into a file called program.in in "overwrite" mode and then passes that file name to the $(CMD) command using the #filename convention that was mentioned.