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Full Discussion: Makefile: Parent - Child Inheritance and export
Top Forums Shell Programming and Scripting Makefile: Parent - Child Inheritance and export Post 302357841 by Shompis on Wednesday 30th of September 2009 06:57:18 PM
Old 09-30-2009
Makefile: Parent - Child Inheritance and export
Hi,

I have a number of Makefiles, including a couple of files that I include in Makefiles, a few scripts that are executed through Makefiles, and I have problems with environment variables that are not inherited to the scripts properly.

Simplified scenario:

rootdir/Makefile:

Code:
all:
     ${MAKE} -C mk alla

rootdir/mk/Makefile:

Code:
export TARGET:= x86

include rootdir/mk/common.mk

alla:
       @echo I am in mk/Makefile

rootdir/mk/common.mk

Code:
$(shell ./print_target.sh)

rootdir/mk/print_target.sh

Code:
#/bin/bash

echo Target is: $TARGET  1>&2

And when I run rootdir/Makefile

I get

Target is:
I am in mk/Makefile

that is, the shell script did not inherit the TARGET environment variable.
However, if I put the export TARGET:= x86 in the root/Makefile instead, then the shell script does inherit the TARGET environment variable, i.e.

Target is: x86
I am in mk/Makefile

Why is that? And what is the solution?

I think I do understand that export will spawn a new child process, thus the makefile where the export is in, can not see it, which is also true for the include as it expands the common.mk.. But I thought that when you run a script, it will also create a child process and it will inherit the export environment variable??

Thanks in advance!
 

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LEARN ABOUT SUSE

xmkmf

XMKMF(1)						      General Commands Manual							  XMKMF(1)

NAME

       xmkmf - create a Makefile from an Imakefile

SYNOPSIS

       xmkmf [ -a ] [ topdir [ curdir ] ]

DESCRIPTION

       The xmkmf command is the normal way to create a Makefile from an Imakefile shipped with third-party software.

       When  invoked with no arguments in a directory containing an Imakefile, the imake program is run with arguments appropriate for your system
       (configured into xmkmf when X was built) and generates a Makefile.

       When invoked with the -a option, xmkmf builds the Makefile in the current directory, and then automatically executes ``make Makefiles'' (in
       case  there are subdirectories), ``make includes'', and ``make depend'' for you.  This is the normal way to configure software that is out-
       side the X Consortium build tree.

       If working inside the X Consortium build tree (unlikely unless you are an X developer, and even then this option is never really used), the
       topdir  argument  should be specified as the relative pathname from the current directory to the top of the build tree.	Optionally, curdir
       may be specified as a relative pathname from the top of the build tree to the current directory.  It is necessary to supply curdir  if  the
       current	directory  has	subdirectories, or the Makefile will not be able to build the subdirectories.  If a topdir is given, xmkmf assumes
       nothing is installed on your system and looks for files in the build tree instead of using the installed versions.

SEE ALSO

       imake(1)

X Version 11							    imake 1.0.2 							  XMKMF(1)
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