fortran fortran - 7 months ago 19
Bash Question

How to assign the output of a command to a Makefile variable

I need to execute some make rules conditionally, only if the Python installed is greater than a certain version (say 2.5).

I thought I could do something like executing:

python -c 'import sys; print int(sys.version_info >= (2,5))'


and then using the output ('1' if ok, '0' otherwise) in a
ifeq
make statement.

In a simple bash shell script it's just:

MY_VAR=`python -c 'import sys; print int(sys.version_info >= (2,5))'`


but that doesn't work in a Makefile.

Any suggestions? I could use any other sensible workaround to achieve this.

Answer

Use the Make shell builtin like in MY_VAR=$(shell echo whatever)

me@Zack:~$make
MY_VAR IS whatever
me@Zack:~$ cat Makefile 
MY_VAR=$(shell echo whatever)

all:
    @echo MY_VAR IS $(MY_VAR)
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