CODEWITHSUNDEEP
gccmakefileverbosity
hernejj
hernejj

Reputation: 4159

How do I force make/GCC to show me the commands?

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.

Upvotes: 415

Views: 507610

Answers (8)

abu_bua
abu_bua

Reputation: 1637

  • In case you want to see all commands (including the compiled ones) of the default target run:
make --always-make --dry-run
make -Bn
  • show commands executed the next run of make:
make --dry-run
make -n

You are free to choose a target other than the default in this example.

Upvotes: 4

Ciro Santilli OurBigBook.com
Ciro Santilli OurBigBook.com

Reputation: 382472

Build system independent method

make SHELL='sh -x'

is another option. Sample Makefile:

a:
    @echo a

Output:

+ echo a
a

This sets the special SHELL variable for make, and -x tells sh 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 the SHELL make variable.

Doing sh -v would be cool as well, but Dash 0.5.7 (Ubuntu 14.04 sh) ignores for -c commands (which seems to be how make uses it) so it doesn't do anything.

make -p will also interest you, which prints the values of set variables.

CMake generated Makefiles always support VERBOSE=1

As in:

mkdir build
cd build
cmake ..
make VERBOSE=1

Dedicated question at: Using CMake with GNU Make: How can I see the exact commands?

Upvotes: 262

Santiago Villafuerte
Santiago Villafuerte

Reputation: 783

I like to use:

make --debug=j

https://linux.die.net/man/1/make

--debug[=FLAGS]

Print debugging information in addition to normal processing. If the FLAGS are omitted, then the behavior is the same as if -d was specified. FLAGS may be a for all debugging output (same as using -d), b for basic debugging, v for more verbose basic debugging, i for showing implicit rules, j for details on invocation of commands, and m for debugging while remaking makefiles.

Upvotes: 18

Ru Hasha
Ru Hasha

Reputation: 956

Depending on your automake version, you can also use this:

make AM_DEFAULT_VERBOSITY=1

Reference: AM_DEFAULT_VERBOSITY

Note: I added this answer since V=1 did not work for me.

Upvotes: 17

Gui13
Gui13

Reputation: 13541

Library makefiles, which are generated by autotools (the ./configure you have to issue) often have a verbose option, so basically, using make VERBOSE=1 or make 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.

Upvotes: 216

TarmoPikaro
TarmoPikaro

Reputation: 5223

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.

Upvotes: 33

Julien Palard
Julien Palard

Reputation: 11526

Since GNU Make version 4.0, the --trace argument is a nice way to tell what and why a makefile do, outputing lines like:

makefile:8: target 'foo.o' does not exist

or 

makefile:12: update target 'foo' due to: bar

Upvotes: 40

chrisaycock
chrisaycock

Reputation: 37930

To invoke a dry run:

make -n

This will show what make is attempting to do.

Upvotes: 403

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