How to make a Makefile executable?

Question

I have a Makefile, and I want make to run automatically when I double-click it (from the Ubuntu file manager). So, I made this Makefile executable, and added at its top the following shebang line:

#!/usr/bin/make -f

When I run /usr/bin/make -f Makefile, I get the desired result.

However, when I double-click the Makefile, or just run ./Makefile, I get an error:

: No such file or directory
clang-9      -o .o
clang: error: no input files
make: *** [<builtin>: .o] Error 1

What is the correct way to make my Makefile executable?

Here are the entire contents of my makefile:

#!/usr/bin/make -f

# A makefile for building pdf files from the text (odt files) and slides (odp files).
# Author: Erel Segal-Halevi
# Since: 2019-02

SOURCES_ODP=$(shell find . -name '*.odp')
TARGETS_ODP=$(subst .odp,.pdf,$(SOURCES_ODP))
SOURCES_ODT=$(shell find . -name '*.odt')
TARGETS_ODT=$(subst .odt,.pdf,$(SOURCES_ODT))
SOURCES_DOC=$(shell find . -name '*.doc*')
TARGETS_DOC=$(subst .doc,.pdf,$(subst .docx,.pdf,$(SOURCES_DOC)))
SOURCES_ODS=$(shell find . -name '*.ods')
TARGETS_XSLX=$(subst .ods,.xlsx,$(SOURCES_ODS))

all: $(TARGETS_ODP) $(TARGETS_ODT) $(TARGETS_DOC) $(TARGETS_XSLX)
    #
    -git commit -am "update pdf files"
    -git push
    echo Done!
    sleep 86400

%.pdf: %.odt
    #
    libreoffice --headless --convert-to pdf $< --outdir $(@D)
    -git add $@
    -git add $<
    
%.pdf: %.doc*
    #
    libreoffice --headless --convert-to pdf $< --outdir $(@D)
    -git add $@
    -git add $<

%.pdf: %.odp
    #
    libreoffice --headless --convert-to pdf $< --outdir $(@D)
    -git add $@
    -git add $<

%.xlsx: %.ods
    #
    libreoffice --headless --convert-to xlsx $< --outdir $(@D)
    -git add $@
    -git add $<

clean:
    rm -f *.pdf

Answer 1

#!/usr/bin/make -f is a valid shebang to allow execution of a Makefile. The problem with your Makefile isn’t its shebang, it’s that it uses Windows line-endings; if you fix that, e.g. with

sed -i $'s/\r$//' Makefile

your Makefile will run correctly.

The difference between using make to run such a Makefile, and running it directly, is that in the latter case, because of the Windows line endings, make is invoked as

make -f $'\r'Makefile

This produces the “No such file or directory” error, since there is no file with a name consisting of a single carriage return. When Make is asked to process a file as a Makefile, it tries to produce it or update it if necessary; since the file that Make is looking for here is missing, it tries to create it. This invokes Make’s built-in rules, which is where the C compiler invocation comes from.