reading variable value declared in script.sh in Makefile - bash

Question

I run makefile to generate an image file for a target device. After I burn the image into the target device during one of the operation funtion1.sh calls script.sh where my VAR is declared.
I want during running Makefile to generate the target image access script.sh knowing the path, read the value of VAR and use it in Makefile.
example:
script.sh:
...
VAR=some_value
...
=====Now what script do I need for Makefile ???===============
-I tried this method but it did not work--------------------------
Makefile:
PLAT_SCRIPT := /path/to/script.sh
PLAT_VAR := VAR
PLAT_SCRIPT_TEXT := $(shell grep ${PLAT_VAR} ${PLAT_SCRIPT}) VAR := $(filter-out ${PLAT_VAR}, $(strip $(subst =, , $(subst ",, $(strip ${PLAT_SCRIPT_TEXT})))))
all:
#echo VAR=$(VAR)
It did not work for some reason. Maybe I should replace line 4 with:
VAR := $(shell echo $(PLAT_SCRIPT_TEXT)|cut -d, -f1|awk -F'=' '{print $2 }' )
all:
#echo VAR=$(VAR)

Answer 1

You must export the variable to make it visible in subprocess.
exporting variable from Makefile to bash script:
export variable := Stop
all:
/path/to/script.sh
or export it using shell style:
all:
variable=Stop /path/to/script.sh
exporting variable from shell to make:
export variable=Stop
make -C path/to/dir/with/makefile
or:
variable=Stop make -C path/to/dir/with/makefile
or:
make -C path/to/dir/with/makefile variable=Stop
If you need to read variable from script you can find it's declaration and extract the value like that:
script.sh:
...
VAR=some_value
...
Makefile:
VAR := $(shell sed -n '/VAR=/s/^.*=//p' script1.sh)
all:
#echo VAR=$(VAR)
But, think this is not a very good method.
Better is to output results of execution in the script and fetch it in Makefile.
Example:
script.sh:
#!/bin/bash
VAR=some_value
# some work here
echo "some useful output here"
# outputting result with the variable to use it in Makefile
echo "result: $VAR"
Makefile:
# start script and fetch the value
VAR := $(shell ./script.sh | sed -n '/^result: /s/^.*: //p')
all:
#echo VAR=$(VAR)