RE: Indirection Operators in the Command section of a makefile doesnt work.

[Rakesh Sharma]

Hello Tim,

 

Thanks for a very detailed response to my query of the heredoc operator in make.

 

My goal for a heredoc inside a makefile was to create a file on the fly from a 
target.

 

Initially I tried using the "define" macro for a multiline for getting this 
done but that didnt work either.

Then zeroed in on the "cat" utility with the heredoc operator.

 

I couldnt make the exmple you gave of the $LINES variable to work at my end.

 

But what I have at my end is :

i) setenv a multiline variable in a csh file .

ii) invoke the make from the csh file, so now the makefile will have access to 
this multiline variable as well. then i do a printf $$multiline variable

inside the makefile.

 

Regards,

Rakesh Sharma
 

> Date: Thu, 16 Jan 2014 14:41:54 +0000
> Subject: Re: Indirection Operators in the Command section of a makefile 
> doesnt work.
> From: address@hidden
> To: address@hidden
> CC: address@hidden
> 
> As I understand it that's a "here document", not merely indirection.
> First check that you have a tab character rather than 9 spaces before
> 'cat'. Then you should get another error like this:
> 
> /bin/sh: warning: here-document at line 0 delimited by end-of-file
> (wanted `EOF')
> 
> 
> Commands in make are single lines but here-documents are multiline.
> You usage creates a line like this:
> 
> cat - <<EOF ; Testing line 1 Testing line 2 EOF
> 
> those '\' characters in your makefile remove the newlines and bash
> sees what I typed above. Try that at your bash commandline - it
> won't work either.
> 
> So you're trying to use a multiline shell feature in a place where
> there will never be multiple lines because in a recipe, every line is
> a separate bash command.
> 
> You can use .ONESHELL but that affects your entire makefile and you
> might not be happy about that.
> 
> I don't know what your goal is (at the moment it seems strange to me
> to use a here document in a makefile) but you might be able to replace
> what you have with something like this:
> 
> 
> LINES=""; read X; while [ $$? -eq 0 ]; do if [ "$$X" == "EOF" ]; then
> break; fi; LINES="$$LINES\n$$X"; read X; done
> 
> This gives you a bash variable, LINES, which you might echo to the
> terminal or whatever you want to do. Your action has to go on the end
> e.g. "; echo -e $$LINES"
> 
> Regards,
> 
> Tm