I'm trying to debug a compilation problem, but I cannot seem to get GCC (or maybe it is make??) to show me the actual compiler and linker commands it is executing.
Here is the output I am seeing:
CCLD libvirt_parthelper
libvirt_parthelper-parthelper.o: In function `main':
/root/qemu-build/libvirt-0.9.0/src/storage/parthelper.c:102: undefined reference to `ped_device_get'
/root/qemu-build/libvirt-0.9.0/src/storage/parthelper.c:116: undefined reference to `ped_disk_new'
/root/qemu-build/libvirt-0.9.0/src/storage/parthelper.c:122: undefined reference to `ped_disk_next_partition'
/root/qemu-build/libvirt-0.9.0/src/storage/parthelper.c:172: undefined reference to `ped_disk_next_partition'
/root/qemu-build/libvirt-0.9.0/src/storage/parthelper.c:172: undefined reference to `ped_disk_next_partition'
collect2: ld returned 1 exit status
make[3]: *** [libvirt_parthelper] Error 1
What I want to see should be similar to this:
$ make
gcc -Wall -c -o main.o main.c
gcc -Wall -c -o hello_fn.o hello_fn.c
gcc main.o hello_fn.o -o main
Notice how this example has the complete gcc
command displayed. The above example merely shows things like "CCLD libvirt_parthelper". I'm not sure how to control this behavior.
To invoke a dry run:
This will show what
make
is attempting to do.Library makefiles, which are generated by autotools (the
./configure
you have to issue) often have a verbose option, so basically, usingmake VERBOSE=1
ormake V=1
should give you the full commands.But this depends on how the makefile was generated.
The
-d
option might help, but it will give you an extremely long output.Use
make V=1
Other suggestions here:
make VERBOSE=1
- did not work at least from my trials.make -n
- displays only logical operation, not command line being executed. E.g.CC source.cpp
make --debug=j
- works as well, but might also enable multi threaded building, causing extra output.Since GNU Make version 4.0, the
--trace
argument is a nice way to tell what and why a makefile do, outputing lines like:or
Depending on your automake version, you can also use this:
Reference: AM_DEFAULT_VERBOSITY
Note: I added this answer since
V=1
did not work for me.Build system independent method
is another option. Sample
Makefile
:Output:
This sets the special
SHELL
variable formake
, and-x
tellssh
to print the expanded line before executing it.One advantage over
-n
is that is actually runs the commands. I have found that for some projects (e.g. Linux kernel) that-n
may stop running much earlier than usual probably because of dependency problems.One downside of this method is that you have to ensure that the shell that will be used is
sh
, which is the default one used by Make as they are POSIX, but could be changed with theSHELL
make variable.Doing
sh -v
would be cool as well, but Dash 0.5.7 (Ubuntu 14.04sh
) ignores for-c
commands (which seems to be howmake
uses it) so it doesn't do anything.make -p
will also interest you, which prints the values of set variables.CMake generated Makefiles
See: Using CMake with GNU Make: How can I see the exact commands?