Clever Geek Handbook

How to avoid whitespace inside a Makefile

Let's say I want to compile a C ++ project located in /home/me/Google Drive/Foobar/

to an executable file named Foobar

and I want to use GNU Make to make this process automatic.

This is what my Makefile looks like:

OUTPUT = $(notdir $(CURDIR))

all $(OUTPUT):
    g++ *.cpp -o $(OUTPUT)

The problem is that there are spaces in the project path, the command notdir

interprets two separate paths and returns Google Foobar

.

I've tried putting quotes around $(CURDIR)

( $(notdir "$(CURDIR)")

), but I'm getting the following error:

/bin/sh: -c: line 0: unexpected EOF while looking for matching `"'
/bin/sh: -c: line 1: syntax error: unexpected end of file
Makefile:4: recipe for target 'all' failed
make: *** [all] Error 1

I don't understand where this problem comes from.

Also, I would appreciate an answer that does not involve changing the path name ... Thanks :)

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4 answers


You can try replacing space

with _

in $(CURDIR)

and then select $(OUTPUT)

. Like below

null      :=
SPACE     := $(null) $(null)
OUTPUT     = $(notdir $(subst $(SPACE),_,$(CURDIR)))

all $(OUTPUT):
    g++ *.cpp -o $(OUTPUT)


So essentially after string substitution (subst) 


$(OUTPUT) will be Foobar
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The problem is that the problem with GNU make in directory storage is less than on the extension side of the shell. So change

 g++ *.cpp -o $(OUTPUT)

in

 g++ *.cpp -o "$(OUTPUT)"

Using a GNU make variant called remake you can see this more easily.



With the remake, if you want to check if $ OUTPUT has a space in it, you can run:

$ remake -X
GNU Make 4.1+dbg0.91
...
-> (/home/me/Google Drive/Makefile:3)
all: 
remake<0> expand OUTPUT
Makefile:1 (origin: makefile) OUTPUT := Google Drive

Now, if you want to see a shell script that does the same things as GNU make, use the write command:

remake<1> write all
File "/tmp/all.sh" written.

everything above is the name of the make target. Then take a look /tmp/all.sh

at which is a shell script and you will see that you have a problem, which of course can be fixed by adding quotes.

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It looks like this combination works in this context.

OUTPUT = "$(notdir $(CURDIR))"
0


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do:

OUTPUT = $(notdir $(lastword $(CURDIR)))

all $(OUTPUT):
    g++ *.cpp -o $(OUTPUT)
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