Make conditionals

Documentation

official docs

https://www.gnu.org/software/make/manual/html_node/Conditional-Syntax.html

if statement

Make conditionals are not indented.

install:
ifdef PKG
    @echo PKG envvar was assigned!
else ifdef GRP
    @echo GRP envvar was assigned!
else
    @echo neither PKG nor GRP were assigned!
endif

# available conditionals
ifeq (arg1, arg2)
ifneq (arg1, arg2)
ifdef arg1
ifndef arg1