[blfs-support] libtool gsl question

Bruce Dubbs bruce.dubbs at gmail.com
Sun May 20 09:08:48 PDT 2012

luxInteg wrote:
> Greetings
> When  I compile gsl-1.15 on by blfs box   I have lines like these in the 
> output:-
> /bin/sh ../libtool --tag=CC   --mode=compile gcc -DHAVE_CONFIG_H -I. -I.. -I..    
> -O3 -fexceptions -m64 -fPIC -MT init2d.lo -MD -MP -MF 
> I  want to know what the M switches i.e. -MT -MD -MP -MF   mean.  I have 
> looked at the man pages of  libtool
> ( http://www.manpagez.com/man/1/libtool/)
> and of the gcc,   and a few other places and found  no explanation for the -MT 
> -MD -MP -MF.

Try the gcc info page:

      Change the target of the rule emitted by dependency generation.
      An `-MT' option will set the target to be exactly the string you

      `-MD' is equivalent to `-M -MF FILE', except that `-E' is not

      When used with `-M' or `-MM', specifies a file to write the
      dependencies to.

      Instead of outputting the result of preprocessing, output a rule
      suitable for `make' describing the dependencies of the main source
      file.  The preprocessor outputs one `make' rule containing the
      object file name for that source file, a colon, and the names of
      all the included files, including those coming from `-include' or
      `-imacros' command line options.

      This option instructs CPP to add a phony target for each dependency
      other than the main file, causing each to depend on nothing.

   -- Bruce

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