Get makefile directory

Question

I am distributing my cpp files along with a makefile. Now the makefile is located in the same directory as the cpp file.

What is the variable (if any) in makefile that allows me to retrieve the current directory where the makefile is located? In this way I can use that variable to specify my cpp path for compilation.

My makefile is as follows:

all:
    g++ ($makeFileDir)/main.cpp ($makeFileDir)/hello.cpp ($makeFileDir)/factorial.cpp -o ($makeFileDir)/hello.exe

Edit: I am running my makefiles on Windows

Answer 1

Here is a cross-platform way to get the directory of the Makefile, which should be fully shell-agnostic.

makeFileDir := $(dir $(abspath $(lastword $(MAKEFILE_LIST))))

Note that this will give you the directory of the Makefile being currently interpreted. You might have bad (or good!) surprises if you include a Malefile using this statement from another.

That should be enough if you use a recent implementation of make for windows, i.e. Chocolatey's.

Issues with older make for Windows

Depending on the version of make you're using on Windows, there can be inconsistencies in the handling of backslashes. You might need one of the following variant. That's the case for GnuWin's make 3.81 binary for example.

• Make the path separator consistent. The statement below uses forward slashes only, just swap \ and / to get the opposite behavior. From my experience (with GnuWin's make), you might have to use forward slashes to use such a variable for make include statements or to use it in VPATH. But you would of course need backslashes in the DOS shell, and therefore in recipes... You might need two versions of the variable, but at least the substitution makes sure that the path separator is consistent!

makeFileDir := $(subst \,/,$(dir $(abspath $(lastword $(MAKEFILE_LIST)))))

• The abspath function of GnuWin make 3.81 is broken and doesn't handle paths with drive letters in it. Here is a workaround to handle Windows absolute paths (with drive letter) as well. You can then use it to get the directory of the Makefile (here with the path separator substitution as well). I won't explain the details, but the workaround simply returns the argument if that's already a Windows absolute path, i.e. if there is : in the root of the path, and uses the builtin abspath otherwise.

define fixabspath
$(if $(findstring :,$(firstword $(subst /, ,$(subst \,/,$(1))))),$\$
$(1),$\
$(abspath $(1)))

makeFileDir := $(subst \,/,$(dir $(call fixabspath,$(lastword $(MAKEFILE_LIST)))))

Remarks

• There might be sources I'm omitting here and I'm sorry for that. It's been a long time ago.
• In the fixabspath definition, $\ are just here to split the line for readability.
• The MAKEFILE_LIST variable contains a list of the Makefiles being interpreted, the last one being the current one. See the corresponding manual page.
• If I remember correctly, this also works with macOS' native make.

Answer 2

I remember I had the exact same problem. It's not possible, as far as I remember. The best bet you can have is to pass it as a variable. That is both cross platform and guaranteed to work, as you know the makefile dir at invoke time (otherwise you can't invoke it).

In alternative, you can do a very dirty trick, meaning you try to combine your current path (you can obtain with $(CURDIR) in gnu make) with the path of the invocation of the makefile (which can be tricky, and depends on your make)