How to source a script in a Makefile?

Question

Is there a better way to source a script, which sets env vars, from within a makefile?

FLAG ?= 0 ifeq ($(FLAG),0) export FLAG=1 /bin/myshell -c '<source scripts here> ; $(MAKE) $@' else ...targets... endif 

Answer 1

Makefile default shell is /bin/sh which does not implement source.

Changing shell to /bin/bash makes it possible:

# Makefile  SHELL := /bin/bash  rule:     source env.sh && YourCommand 

Answer 2

To answer the question as asked: you can't.

The basic issue is that a child process can not alter the parent's environment. The shell gets around this by not forking a new process when source'ing, but just running those commands in the current incarnation of the shell. That works fine, but make is not /bin/sh (or whatever shell your script is for) and does not understand that language (aside from the bits they have in common).

Chris Dodd and Foo Bah have addressed one possible workaround, so I'll suggest another (assuming you are running GNU make): post-process the shell script into make compatible text and include the result:

shell-variable-setter.make: shell-varaible-setter.sh     postprocess.py @^  # ... else include shell-variable-setter.make endif 

messy details left as an exercise.