GNU-Make: how to copy files from source to destination - gnu-make

I know this is a basic question but I'm missing something fundamental about makefiles.
Take this simple rule/action:
doc: ${SRC_DIR}/doc/dir1/file1.pdf ${SRC_DIR}/doc/dir1/file2.pdf
cp $? ${DEST_DIR}/doc/
the first time I run it, it copies file1.pdf and file2.pdf to the destination/doc directory. Perfect. I'm expecting the next time I run it, for it to do nothing. The source files haven't changed, aren't they a dependency? But when I run I get :
cp : cannot create regular file ..... :Permission denied.
so, 2 questions:
1) Why is it trying to do it again? When I run make -d I see it eventually says: No need to remake target .../file1.pdf and .../file2.pdf but then
it says : must remake target 'doc'
If it doesn't need to make either pdf file, why does it need to make doc?
2) say the pdf files had changed in the source, they are read only though, so it gets the permission denied error. How do you get around this?

A make rule:
target: preqreq0 prereq1...
command
...
says that target needs to be (re)made if it does not exist or is older than
any of the prerequisites preqreq0 prereq1..., and that target shall be
(re)made by running the recipe command ....
Your rule:
doc: ${SRC_DIR}/doc/dir1/file1.pdf ${SRC_DIR}/doc/dir1/file2.pdf
cp $? ${DEST_DIR}/doc/
never creates a file or directory doc, so doc will never exist when
the rule is evaluated (unless you create doc by other means), so the recipe
will always be run.
The kind of target that I believe you want doc to be is a phony target,
but you are going about it wrongly. A reasonable makefile for the purpose would
be:
SRC_DIR := .
DEST_DIR := .
PDFS := file1.pdf file2.pdf
PDF_TARGS := $(patsubst %,$(DEST_DIR)/doc/%,$(PDFS))
.PHONY: doc clean
doc: $(PDF_TARGS)
$(DEST_DIR)/doc/%.pdf: $(SRC_DIR)/doc/dir1/%.pdf
cp $< $#
clean:
rm -f $(PDF_TARGS)
I recommend The GNU Make documentation
As for your second problem, how to overwrite "readonly" files, it is unrelated to make.
You cannot overwrite files to which you do not have write permission, regardless
of the means by which you try to do it. You must get write permission to any files
that you need to write to. It is a system administration matter. If you do not
understand file permissions you may find help at sister-site Unix & Linux
or serverfault

Related

Conditionally source a script in zsh

I currently source an initializations script in my .zshrc. Unfortunately this makes some modifications to my environment and $PATH I don't want, unless I'm in some specific directories.
Sure, I could compare the output of pwd with the current dir, but I would like to source if I'm in a specific directory or one of its subdirectories at any level.
And is there probably an entirely different solution to my problem?
Using a child process just to run pwd is overkill. You find your current directory always stored in the variable PWD. This variable is maintained automatically by zsh.
You can find whether your working directory is in or below a certain directory dir by
if [[ $PWD:A == $dir:A || $PWD:A == $dir:A/** ]]
then
# I am in $dir or below it
...
fi
The :A takes care of the cases where one of the path components involved in the comparision happens to be a symlink. I'm not sure whether you will need this for PWD, but it does not harm using it.

Recursively copy the *contents* of a directory

Using any of the standard Robot libraries, is it possible to recursively copy the contents of a directory to an existing destination directory?
Basically, I'm looking for the equivalent of the following shell command: cp -r foo/. bar (note the trailing dot)
I tried Copy Directory but this creates a directory foo inside bar (as documented) and it doesn't stop doing that even when supplying the trailing dot. Copy Files chokes when it encounters a directory.
Is there anything I overlooked? Or do I need to just call cp -r myself?
As I only need this to work on Linux, I ended up implementing a custom keyword calling cp -r. If this is ever needed cross-platform, then I'll follow the suggestions to directly implement it in Python.
Copy Directory Contents
[Documentation] Recursively copies the contents of the source directory into the destination.
[Arguments] ${source} ${destination}
Directory Should Exist ${source}
Directory Should Exist ${destination}
${result} = Run Process cp -r ${source}/. ${destination}/
Should Be Equal As Integers ${result.rc} 0

If condition inside the %Files section on a SPEC file

I'm kinda a new to writing spec files and building RPM's. Currently I have one RPM that is supposed to deploy some files in 1 of 2 possible directories that will vary with the OS.
How can I, within the %files section, verify them? I can't use variable...I can't verify both paths because one will for sure fail...I tried to define a macro earlier in the %install section but it will be defined just once and won't be redefined on every RPM installation...
what can I do here?
Thanks
I had a similar situation where additional files were included in the RPM in case of a DEBUG build over and above all files in the RELEASE build.
The trick is to pass a list of files to %files alongwith a regular list of files below it:
%install
# Create a temporary file containing the list of files
EXTRA_FILES=$RPM_BUILD_ROOT/ExtraFiles.list
touch %{EXTRA_FILES}
# If building in DEBUG mode, then include additional test binaries in the package
%if %{build_mode} == "DEBUG"
# %{build_mode} is a variable that is passed to the spec file when invoked by the build script
# Like: rpmbuild --define "build_mode DEBUG"
echo path/to/file1 > %{EXTRA_FILES}
echo path/to/file2 >> %{EXTRA_FILES}
%endif
%files -f %{EXTRA_FILES}
path/to/release/file1
path/to/release/file2
In your case, you can leverage the %if conditional in the %install section, use the OS as a spec variable passed to rpmbuild (or detect it in the RPM spec itself) and then pass the file containing the list to %files
The %files section can have variables in it, but usually this would be something like your path that is defined so you don't have to repeat it a bunch. so %{long_path}/file_name, where long_path was defined earlier in the spec file. the %files section is all the information that goes into the RPM database, and is created when you build the RPM so you won't be able to change those values based on machine information when installed.
If you really want to do this, you could include a tar file inside of the main tarball that gets extracted depending on certain conditions (since the spec file is just bash). Now keep in mind this is an awful idea. The files won't be tracked by the RPM database, so when you remove the RPM these files will still exist.
In reality you should build two RPMs, this will allow for better support going forward into the future in the event you have to hand this off to someone, as well as preserving your own sanity a year from now when you need to update the RPM.
This is how I solved my problem
step 1 :
In Build section .. somewhere I wrote :
%build
.....
#check my condition here & if true define some macro
%define is_valid %( if [ -f /usr/bin/myfile ]; then echo "1" ; else echo "0"; fi )
#after his normal continuation
.....
...
Step 2: in install section
%install
......
#do something in that condition
if %is_valid
install -m 0644 <file>
%endif
#rest all your stuff
................
Step 3:in files section
%files
%if %is_valid
%{_dir}/<file>
%endif
That's it
It works.
PS : I cannot give you full code hence giving all useful snippet
Forrest suggests the best solution, but if that is not possible practical you can detect the OS version at runtime in the post-install section, move the script to the appropriate location, and then delete it post-uninstall, eg:
# rpm spec snippets
%define OS_version %(hacky os detection)
...
Source2: script.sh
...
%install
install %{_sourcedir}/script.sh %{buildroot}/some/known/location
...
%post
%if %{OS_version} == "..."
mv /some/known/location/script.sh /distro/specific/script.sh
%elif %{OS_version} == "..."
...
%preun
rm -rf /all/script/locations
Much more error prone than building different RPMs on different OSes, but will scale a little better if you need to support many different OSes.

How to preserve file permissions with cmake "install directory" directive?

Prolog: I'm an idiot for missing this in the documentation
cmake-2.8.10.2
How do you make cmake preserve the original file permissions when installing a directory? For the project at hand, I'd like it to essentially copy some directories from my source tree to the install tree. To wit:
install(
DIRECTORY config runp
DESTINATION ${CMAKE_INSTALL_PREFIX}
PATTERN ".svn" EXCLUDE
PATTERN ".git" EXCLUDE
PATTERN "start_collection.snl" EXCLUDE
)
All works as expected -- except that executable scripts are getting copied in with incorrect file permissions. In fact, none of the original file permissions are preserved. Globally setting permissions using FILE_PERMISSIONS and DIRECTORY_PERMISSIONS is something I do not want to do, and frankly, would be a hack in this context.
In the shell-scripting world, I'd do something simple like this:
for i in config runp ; do
tar cf - $i | tar -C $CMAKE_INSTALL_PREFIX -xf -
done
Documentation suggests using USE_SOURCE_PERMISSIONS when calling install():
install(
DIRECTORY config runp
DESTINATION ${CMAKE_INSTALL_PREFIX}
USE_SOURCE_PERMISSIONS
PATTERN ".svn" EXCLUDE
PATTERN ".git" EXCLUDE
PATTERN "start_collection.snl" EXCLUDE
)
Alternatively, you can use install(PROGRAMS signature of this command. See docs for more info.

Can 'make' check if mtime of a dependency is *different* between runs, not just if it's newer than target?

If foo_user.cpp depends on foo.h, then foo_user.cpp is built, and then foo.h's modification time is set to further in the past, make will not rebuild foo_user.cpp (because foo.cpp is 'newer'). I'd prefer it if make recorded the modification times of dependencies, and if they changed at all (newer or older), to consider targets of that dependency to be out of date. Can GNU make do this? If not, is there an easy alternative?
In case you're curious how this situation arises: foo.h resides in a symlinked folder. The symlink may point to the foolib-1.0 folder, the foolib-2.0 folder, etc. When the symlink points at a different version of the library, even an older version, foo_user.cpp should be rebuilt. If I simply specifiy symlinkfolder/foo.h as a dependency of foo_user.cpp, make only pays attention to the timestamp of foo.h, not the timestamp of the symlink'd directory through which foo.h is accessed. I can't add the symlink itself as a dependency, because the make rule is generated by the compiler (GCC has a special flag that when given causes it to output a make rule for all the headers a source file depends on).
I'm trying to understand why you can't just add the symlink as a dependency. I imagine your automatic dependencies are on one line, but you can have as many as you want.
x.o: a.h b.h
x.o: c.h
x.o: d.h
But having said that, it seems likely that make will stat the symlink's target, and not the symlink itself, so that may not DTRT. I suppose you could just touch a file somewhere whenever you make the symlink, but I also suppose you've already thought of that...
You could have a rule that runs ls -id link/. > test, which will put the inode number of the link target directory in test. You could then cmp test save, where save is from the last run. You could then have that make rule do make clean && make target if they are different.
targetwrapper:
ls -id link/. > test
cmp test save || make clean
make realtarget
cp test save
clean:
echo cleaned
realtarget:
echo made
No, Make does not support this. You may wish to consider using another build system such as SCons, which does not rely solely on the timestamp but actually computes the MD5 hash of source files and bases its decisions on the hashes.
From "What makes SCons better?" on its web site:
Reliable detection of build changes using MD5 signatures; optional, configurable support for traditional timestamps.
While make doesn't support it out of the box, you can program it.
include more_deps
ifneq ($(MAKE_RESTARTS),)
more_deps:
if (foolink.old differs from what foolink points to) ; then \
readlink foolink > foolink.old ; \
echo "foo_user: foolink_trigger" > more_deps ; \
touch foolink_trigger ; \
else \
echo "" > more_deps ;\
fi
endif
foo_user: foo_user.cpp
g++ $^ -o $#
Here you include makefile more_deps which sometimes will include the dependency on the symlink's trigger. Trigger is a special intermediate flie, all the meaningful informaion in which is its timestamp. When the symlink changes, the timestamp of the trigger is updated to current time (see touch), thus making foo_user outdated and it is the rebuilt.
include and MAKE_RESTARTS are needed to restart make after calculating the dependency described above. If the makefile being included is a target itself, the target is considered to be rebuilt, is rebuilt and then make restarts and re-reads makefile. But when it reads makefile for the second time, it doesn't see more_deps as a target, because MAKE_RESTARTS variable expands to non-empty string.
In fact, the line with if can sound like this:
more_deps:
if (any condition you want with $(VARIABLES) possible!) ; then \
update a file that holds the previous state ;\
...
Through which process do you change the symlink? You could add a make clean type of action to the script that changes the symlink.
You could also set up a "header working folder" in with you let make copy your header files, where the copied header files are dependent on their original and the symlink. The dependencies generated by GCC only take the working headers into account and won't clash with your copy headers into the working folder part of your Makefile.

Resources