Escaping in makefile

Question

I'm trying to do this in a makefile and it fails horribly:

M_ARCH := $(shell g++ -dumpmachine | awk '{split($1,a,"-");print a[1]}')

do you know why? I guess it has to do with escaping, but what and where?

How does it fail? What error messages does it produce? What do you expect it to do? — , Mar 04 '10 at 21:20

score 177 · Accepted Answer · answered Mar 04 '10 at 21:21

177

It's the dollar sign, in makefiles you'll have to type $$ to get a single dollar sign:

M_ARCH := $(shell g++ -dumpmachine | awk '{split($$1,a,"-");print a[1]}')

answered Mar 04 '10 at 21:21

Martin

138

Yeah, make is a total waste of money: you have to put two `$` to get one. – P Shved Mar 04 '10 at 21:31
8

@PavelShved I've never once paid for make. :) – Trevor Hickey Oct 31 '12 at 02:29
For anyone finding this answer as part of a search, there are also problems with '#' characters that are taken as the start of comments. For these, you should escape with a backslash: "\#". – Jim Monte Jan 28 '20 at 06:05

richq · Answer 2 · 2010-08-07T22:11:26.153

18

Make is quite lispy when you get down to it. Here's a non-awk version that does the same thing:

space := $() #

M_ARCH := $(firstword $(subst -,$(space),$(shell g++ -dumpmachine)))

all:
    $(info $(M_ARCH))

edited Aug 07 '10 at 22:11

answered Mar 04 '10 at 21:41

richq

2 Answers2