Re: how to output newline at the end of making a target (on Windows)

[Paul Smith]

On Sun, 2009-11-29 at 14:30 -0800, Mark Galeck (CW) wrote:
> Hello,
> 
> SHELL=cmd.exe
> foobar:
>               @echo.
> 
> gives me:
> C:\tmp>make foobar
> process_begin: CreateProcess(NULL, echo., ...) failed.
> make (e=2): The system cannot find the file specified.
> make: *** [foobar] Error 2
> 
> 
> However, I do use "echo." process all the time on Windows, just
> outputting to a file - this works perfectly fine:
> 
> SHELL=cmd.exe
> foobar:
>               @echo.>foo
> 
> and 
> C:\tmp>make foobar
> works fine, foo gets a newline (no errors either in foo or on standard
> out).  
> 
> Why is this so??

This is really a Windows-specific question so it will be more likely to
be answered accurately if you ask on the address@hidden mailing list.

However, I'd guess that this is due to make's fast path processing: if
make can determine that the command you're invoking does not need a
shell, it won't start one; instead it will simply try to invoke the
command directly.

In this case, the command "echo." is not known to make as a command that
requires a shell, so it tries to run it directly.  In reality this is
not a real command but rather a builtin command for the Windows shell
(for example command.com), so trying to invoke it directly fails.

On the other hand, when you run "echo.>foo" make sees the redirection
(">") and understands that this is not a simple command and can't be run
using the fast path, so it invokes the shell to run it and it works.

Make knows the command "echo" is a shell builtin, but not "echo.".
Someone else will need to judge whether "echo." should be added as a
builtin, or whether something else should be done.

-- 
-------------------------------------------------------------------------------
 Paul D. Smith <address@hidden>          Find some GNU make tips at:
 http://www.gnu.org                      http://make.mad-scientist.net
 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist