If conditions in a Makefile inside a target

Question

I m trying to setup a Makefile that will search and copy some files  if-else condition  and I can t figure out what exactly is wrong with it   thou I m pretty sure it s because a combination of spaces tabs written in the wrong place   Can I get some help with it  please   Here s what I have currently   obj-m   linuxmon o  KDIR    lib modules   shell uname -r  build UNAME      shell uname -m   all         info Checking if custom header is needed      ifeq    UNAME   x86 64            info Yes          F1 EXISTS   shell   -e  usr include asm unistd 32 h    amp  amp  echo 1    echo 0           ifeq    F1 EXISTS   1                info Copying custom header                shell sed -e  s   NR    NR32  g   usr include asm unistd 32 h  gt  unistd 32 h          else                 F2 EXISTS   shell    -e  usr include asm-i386 unistd h     amp  amp  echo 1    echo 0               ifeq    F2 EXISTS   1                    info Copying custom header                    shell sed -e  s   NR    NR32  g   usr include asm-i386 unistd h  gt  unistd 32 h              else                   error asm unistd 32 h and asm-386 unistd h does not exist              endif         endif           info No      endif       make -C   KDIR  M   PWD  modules  clean      make -C   KDIR  M   PWD  clean     rm unistd 32 h   Anyways  that ll print  Yes    Copying header  twice and then it will quit saying that sed can t read  usr include asm-i386 unistd h  which of course it can t read as I m on a x64 system   I could say that make just isn t understanding the if else and instead is running everything line by line

User · Accepted Answer

There are several problems here  so I ll start with my usual high-level advice  Start small and simple  add complexity a little at a time  test at every step  and never add to code that doesn t work   I really ought to have that hotkeyed    You re mixing Make syntax and shell syntax in a way that is just dizzying  You should never have let it get this big without testing  Let s start from the outside and work inward   UNAME      shell uname -m   all        info Checking if custom header is needed      ifeq    UNAME   x86 64          do some things to build unistd 32 h     endif       make -C   KDIR  M   PWD  modules   So you want unistd 32 h built  maybe  before you invoke the second make  you can make it a prerequisite  And since you want that only in a certain case  you can put it in a conditional   ifeq    UNAME   x86 64  all  unistd 32 h endif  all       make -C   KDIR  M   PWD  modules  unistd 32 h          do some things to build unistd 32 h   Now for building unistd 32 h   F1 EXISTS   shell   -e  usr include asm unistd 32 h    amp  amp  echo 1    echo 0   ifeq    F1 EXISTS   1        info Copying custom header        shell sed -e  s   NR    NR32  g   usr include asm unistd 32 h  gt  unistd 32 h  else         F2 EXISTS   shell    -e  usr include asm-i386 unistd h     amp  amp  echo 1    echo 0       ifeq    F2 EXISTS   1            info Copying custom header            shell sed -e  s   NR    NR32  g   usr include asm-i386 unistd h  gt  unistd 32 h      else           error asm unistd 32 h and asm-386 unistd h does not exist      endif endif   You are trying to build unistd h from unistd 32 h  the only trick is that unistd 32 h could be in either of two places  The simplest way to clean this up is to use a vpath directive   vpath unistd h  usr include asm  usr include asm-i386  unistd 32 h  unistd h     sed -e  s   NR    NR32  g    lt   gt

User · Answer

You can simply use shell commands  If you want to suppress echoing the output  use the     sign  For example   clean       if    test     test     then          echo  Hello world        fi   Note that the closing     and     are necessary

[if-statement] If conditions in a Makefile, inside a target

Examples related to if-statement

Examples related to makefile

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