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

Question

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.

This looks like Kbuild or Autotools output. Try make V=1. — jww
– jww, Commented Mar 21, 2016 at 2:10
Related: the opposite question Control the output of a make command to be less verbose, don't echo each command — smci
– smci, Commented Mar 14, 2018 at 10:54

Zombo · Accepted Answer · 2017-01-08 04:43:25Z

409

To invoke a dry run:

make -n

This will show what make is attempting to do.

edited Jan 8, 2017 at 4:43

Zombo

1

answered Apr 28, 2011 at 14:40

chrisaycock

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8 Comments

hernejj Over a year ago

Found it :) make V=1 Although the above suggestion of "make -n" worked as well. :) Thank you all for your responses.

m-ric Over a year ago

Difference is that make -n does not execute the commands. Thus correct answer is make V=1

larsr Over a year ago

make V=1 is only working if the Makefile supports it. automake's makefiles do that, but many others don't.

Ruslan Over a year ago

For CMake, use make VERBOSE=1; for GNU autotools make V=1.

Ciro Santilli OurBigBook.com Over a year ago

@m-ric if you want to run actually run the commands, consider make SHELL='sh -x': stackoverflow.com/a/32010960/895245

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Ciro Santilli OurBigBook.com · Accepted Answer · 2020-09-01 14:41:12Z

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?

Definitely the best answer which doesn't depend on how well the original Makefile was written/generated
make SHELL='$$SHELL -x' will make $SHELL literal which is not evaluated. Using make SHELL="$SHELL -x" will work.
this is the best generic answer, in contrast to some other answers this does not depend on using cmake

Peter Mortensen · Accepted Answer · 2019-07-06 02:12:32Z

218

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.

edited Jul 6, 2019 at 2:12

Peter Mortensen

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answered Apr 28, 2011 at 14:44

Gui13

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3 Comments

blinry Over a year ago

Note: CMake-generated Makefiles only support VERBOSE=1, not V=1.

jcomeau_ictx Over a year ago

V=1 worked for me, compiling nuttx with mips-linux-gnu-gcc, thank you.

Louis Go Over a year ago

Interestingly, autotool supports V=1 while not supporting VERBOSE=1... contrary to cmake...

Flow · Accepted Answer · 2017-05-09 12:15:50Z

40

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

edited May 9, 2017 at 12:15

Flow

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answered May 21, 2016 at 21:45

Julien Palard

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2 Comments

makerj Over a year ago

This argument prints more detailed information than dry run. It is very helpful to understand make systems which has complex build process like dpdk.

einpoklum Over a year ago

@makerj: Perhaps, but it does actually execute the commands, unlike make -n.

TarmoPikaro · Accepted Answer · 2018-06-22 21:39:01Z

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.

make VERBOSE=1 is for CMake. Your trials were most likely with GNU autotools-based projects.

Santiago Villafuerte · Accepted Answer · 2020-07-01 14:17:30Z

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.

It doesn't necessarily show the command it executes. You may just get Reaping winning child xyz and Jobserver client (fds 3,4) and Need a job token; we don't have children and so on.

Peter Mortensen · Accepted Answer · 2019-07-06 02:13:46Z

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.

abu_bua · Accepted Answer · 2022-11-24 21:44:30Z

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.

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