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

User · Answer

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

User · Answer

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

User · Answer

To invoke a dry run   make -n   This will show what make is attempting to do

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

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

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