Re: Variable confusion

[Paul Smith]

On Tue, 2010-06-15 at 15:51 +0200, Gary wrote:
> Sorry. Can't see for looking, can I! I mean the echo produces the
> -I burble, while the invocation of the "compiler" (gpp -x blah) shows
> the command "`find ...".

Ah.  Yes, Greg explained that to you.  The variable contains whatever
string you provided, which in this case is a backquoted command.  Make
doesn't _interpret_ that string, it just stores it.

Then you use it in a command, and the string is passed to the shell (but
still as a string, not the expansion of the string).  Then the shell
runs that command.

You probably would have been able to figure it out faster if you'd not
had the "@" hiding the echo command.  Then you would have seen this:

>> $ make echo
>> echo `find ${LIB_ROOT} -type d \! \( -name '.*' -prune \) | sed -e 's/^/-I 
>> /'`
>> -x --curdirinclast -I ../lib -I ../lib/db -I ../lib/ewz -I ../lib/ewz/ws -I 
>> ../lib/net -I ../lib/net/protocol -I ../lib/net/protocol/http

And this:

>> $ make echo
>> echo `find ${LIB_ROOT} -type d \! \( -name '.*' -prune \) | sed -e 's/^/-I 
>> /'`
>> -x --curdirinclast -I ../lib -I ../lib/db -I ../lib/ewz -I ../lib/ewz/ws -I 
>> ../lib/net -I ../lib/net/protocol -I ../lib/net/protocol/http
>> gpp -x --curdirinclast `find ../lib -type d \! \( -name '.*' -prune \) | sed 
>> -e 's/^/-I /'` -o FOO.php FOO.gpp

Using "@" is very handy once your makefile is completed and you don't
want to bother people with details, but I find that most of the time
it's just hiding potentially important information when makefiles are
being developed.

-- 
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