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I have a definitions.mk file with some definitions:
define some-method
if [ ! -f <some file> ] ; then
MYVAR += text_to_append
It is the line with MYVAR that is my problem. It thinks MYVAR is a command. How can I make it realize that it is the variable MYVAR (which also exists in other make files) that I am referring to?
Thanks in advance for any input!
255
makefile Variables Appending Text To an Existing Variable The += operator is a common extension that adds the specified content to the end of the variable, separated by a space. Variable references in the right-hand side will be expanded if and only if the original variable was defined as a simply-expanded variable.
+= is used for appending more text to variables e.g. objects=main.o foo.o bar.o. objects+=new.o. which will set objects to 'main.o foo.o bar.o new.o' = is for recursively expanded variable.
The ifeq directive begins the conditional, and specifies the condition. It contains two arguments, separated by a comma and surrounded by parentheses. Variable substitution is performed on both arguments and then they are compared.
In python, to append a string in python we will use the ” + ” operator and it will append the variable to the existing string.
You can't use a shell-style "if" statement in a Makefile. You need to use the GNU make conditional syntax.
Something like:
ifneq ($(wildcard some_file),)
# File exists
MYVAR += text_to_append
endif
Also, do not use tabs for indentation in your Makefile, they have special meaning to Make.
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