Yes of course. I'm sorry for the mis-direction. Please try this code:
test:
@export QA_STEP=start; touch $${QA_STEP}
The double-dollar sign tells make to pass the reference on, rather than
dereferencing it in the makefile.
John
On Sat, Feb 28, 2009 at 11:36 AM, kalyan <[email protected]> wrote:
> Hi John,
> I actually tried out these examples:
>
> case 1:
> test:
> @export QA_STEP=start;touch ${QA_STEP}
> This case actually gave the error of "touch: file arguments missing". Note
> that using curly or normal braces gave the same error.
>
> If i understand correctly, the reason for failure is that make tries to
> de-references all the variables before it passes the contents to the shell.
> Before passing the contents to the shell, make tried to evaluate QA_STEP
> which ofcourse turned out to be empty and hence the error.
>
> case 2:
> export QA_STEP=start
>
> test:
> @touch ${QA_STEP}
>
> This case worked perfectly :)
>
> Regards
> Kalyan
>
>
>
>
> On Fri, Feb 27, 2009 at 10:20 PM, John Calcote <[email protected]>wrote:
>
>> Kaylan,
>>
>>
>>
>> There are two contexts for the export keyword here. Make supports an
>> export keyword, and the shell also support an export keyword. These two
>> contexts are separate and not related to each other in any way. When a **
>> command** uses export, its context is only within the shell assigned to
>> run that command.
>>
>>
>>
>> This is why you need to ensure that both the export command, and the
>> following command that uses the exported shell variable are both executed by
>> the same shell. Since each command is executed by a separate shell, you need
>> to use a semicolon and an optional backslash. If you don’t want to use a
>> backslash, you can simply append the two lines into one like this:
>>
>>
>>
>> test:
>>
>> export QA_STEP=start; touch ${QA_STEP}
>>
>>
>>
>> Outside of **commands**, the word export is used to communicate that a **
>> make** variable should be exported to child processes of the current make
>> process—so that make variable will be available to child make processes –
>> like this:
>>
>>
>>
>> export QA_STEP_MAKE_VAR=start
>>
>>
>>
>> test:
>>
>> touch $(QA_STEP_MAKE_VAR)
>>
>>
>>
>> Also note the difference in dereference syntax. Make variables are
>> dereferenced by make before the command is passed to the shell by using $()
>> syntax, whereas shell variables are dereferenced by the shell after it
>> receives the command, by using the ${} syntax.
>>
>>
>>
>> John
>>
>>
>>
>> *From:* kalyan [mailto:[email protected]]
>> *Sent:* Thursday, February 26, 2009 8:39 PM
>> *To:* John Calcote
>> *Cc:* albob; [email protected]
>> *Subject:* Re: Using environmnet variables in make
>>
>>
>>
>> i guess backslash wouldnt work because export is not recognized as a shell
>> command in make..
>> Also, make manual hints that export can be used to communicate variables
>> to sub-make, so i am not sure if exporting a variable and using it in the
>> same makefile would work..
>>
>> kalyan
>>
>> On Fri, Feb 27, 2009 at 4:38 AM, John Calcote <[email protected]>
>> wrote:
>>
>> Alan,
>>
>> Try adding a backslash after the export QA... statement like this:
>>
>>
>> test:
>> export QA_STEP=start; \
>> touch ${QA_STEP};
>>
>> make executes each line in a separate shell, so QA_STEP will not be set in
>> the shell that executes the touch statement unless you execute both
>> commands
>> in the same statement.
>>
>> John
>>
>>
>> -----Original Message-----
>> From: [email protected]
>> [mailto:help-make-bounces+john.calcote <help-make-bounces%2Bjohn.calcote>
>> [email protected]] On Behalf Of albob
>> Sent: Thursday, February 26, 2009 10:28 AM
>> To: [email protected]
>> Subject: Using environmnet variables in make
>>
>>
>> Hi,
>> I have the following Makefile
>>
>> .EXPORT_ALL_VARIABLES:
>> .SUFFIXES:
>>
>> test:
>> export QA_STEP=start ;
>> touch ${QA_STEP};
>>
>> Which I run using "gmake". This gives me:
>>
>> slappy628: gmake test
>> export QA_STEP=qa_rtl ;
>> touch ;
>> touch: file arguments missing
>> Try `touch --help' for more information.
>> gmake: *** [test] Error 1
>>
>> Can anyone tell me what I am doing wrong? No matter what I try I can not
>> get
>> it to pick up on the environment variable set. Help would be much
>> appreciated.
>> Thanks
>> Alan
>>
>> --
>> View this message in context:
>>
>> http://www.nabble.com/Using-environmnet-variables-in-make-tp22229241p2222924
>> 1.html<http://www.nabble.com/Using-environmnet-variables-in-make-tp22229241p2222924%0A1.html>
>> Sent from the Gnu - Make - Help mailing list archive at Nabble.com.
>>
>>
>>
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>
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