CODEWITHSUNDEEP
makefile
gutelfuldead
gutelfuldead

Reputation: 602

Using tab character in Makefile $(info ...)

I would like to add tabs specifically to the stdout text in a makefile. I've tried placing tabs directly into the text as well as using a \t command and neither work.

I could always achieve the same with spaces but it is just annoying.

$(info test text with tabs)

tabs are completely removed on output

$(info \ttest text)

becomes : "\ttest text" on output

Is there a reasonable way to do this? I am aware I can do this with

@echo -e "\tNow the tabs work!"

However I was trying to get rid of using echos.

Thanks

edit :

I was wrong about using spaces instead -- they are just deleted on the output just like inserted tabs are.

Upvotes: 4

Views: 2714

Answers (1)

Renaud Pacalet
Renaud Pacalet

Reputation: 29280

make strips strings before using them as arguments of various commands or statements. So, let's first define a variable containing... nothing, use it to define a variable containing a tab and use that variable when needed:

$ cat Makefile
NULL :=
TAB  := $(NULL)<tab>$(NULL)

all:
    $(info X$(TAB)X)

$ make
X    X
make: 'all' is up to date.

I used <tab> to show where the tab character must go. Use the real tab character instead, of course. Note that NULL alone is enough for what you want:

$ cat Makefile
NULL :=

all:
    $(info $(NULL)<tab>X)

$ make
    X

But having a TAB variable is maybe more convenient.

Note also that make variables can have very strange names. If you prefer naming the variable \t instead of TAB, you can:

$ cat Makefile
NULL :=
\t   := $(NULL)<tab>$(NULL)

all:
    $(info X$(\t)X)

$ make
X    X
make: 'all' is up to date.

You can even define \n for end-of-line:

$ cat Makefile
NULL :=
\t   := $(NULL)<tab>$(NULL)
define \n


endef

all:
    $(info X$(\t)X$(\n)Y$(\t)Y)

$ make
X    X
Y    Y
make: 'all' is up to date.

The reason why we need two empty lines in the define-endef can be found in the GNU make manual:

The value in an ordinary assignment cannot contain a newline; but the newlines that separate the lines of the value in a define become part of the variable’s value (except for the final newline which precedes the endef and is not considered part of the value).

Upvotes: 5

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