How to get the basename of the parent directory of a makefile in GNU make?

Question

Suppose you want to have a makefile that shall generate one file named after the parent directory. One way to do that is to hard-code the target name but that's not very "generic", eg

TARGET := dirname.pdf

$(TARGET): $(TARGET:.pdf=.tex)
    pdflatex $(@:.pdf=.tex)

It would be much nicer to retrieve the directory name via make functions. There are various questions (and answers) on SA on how to retrieve the full path of a makefile (eg, https://stackoverflow.com/a/18137056/1905491 ) but not the name of the parent directory...

What's the most efficient and portable way to do that in GNU make?

Answer 1

Why not just use the built-in file name functions ?

TARGET := $(notdir $(CURDIR))

I guess I'm not sure what you mean by "parent directory"; it's a bit ambiguous. A specific example with a pathname and the result you wanted would make it easier to understand.

Answer 2

It depends very much on what you mean by "parent" directory. After all, make can only operate on strings and has no real notion of directories and files in terms of a datatype. You can eg extract the last name of a path by calling this function:

parent_name = $(lastword $(subst /, ,$(dir $(abspath $1))))
$(info $(call parent_name,/home/stefanct/myproject/foo.c))

Output:

myproject

Answer 3

If you have GNU make >4.0 with guile-support (output of $(info .FEATURES) contains guile ) and the basename does not contain spaces the following solution works without any external dependencies or subprocesses:

MAKEFILE_PATH:=$(abspath $(lastword $(MAKEFILE_LIST)))
MAKEFILE_PATH_ELEMS:=$(subst /, ,$(MAKEFILE_PATH))
PARENT_DIR:=$(word $(guile (- $(words $(MAKEFILE_PATH_ELEMS)) 1)),$(MAKEFILE_PATH_ELEMS))

Unfortunately, guile support is not enabled by default by (all/many?) distributions and thus this requires to install a distinctive package (eg, make-guile on Ubuntu) that provides guile support and replaces the ordinary make .

Answer 4

If by parent directory you mean:

Makefile path:

/some/file/path/Makefile

Makefile directory:

/some/file/path

Parent directory (of Makefile)

/some/file

Then the following simple code is probably what you're looking for:

 MK_PATH:=$(dir $(realpath $(lastword $(MAKEFILE_LIST))))
 MK_PARENT:=$(realpath $(MK_PATH)../)