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Posted to user@ant.apache.org by Raja Nagendra Kumar <Na...@tejasoft.com> on 2009/12/30 07:56:32 UTC
Reading environment variables in ant script directly
Hi,
Is it possible to read OS environment variables directly in ant script
without the line
<property environment="evn"/>
As ant is java and by default all the ant variables would be passed to JRE
on each java invocation, I am looking for a way to get the value of the
property variables directly.
Why another line if I could avoid it. Also helps in managing few thing more
smartly without this call each project.
Regards,
Raja Nagendra Kumar,
C.T.O
www.tejasoft.com
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RE: Reading environment variables in ant script directly
Posted by Rez P <po...@hotmail.com>.
I'm not sure if there're any other reasons but to me it's very obvious so one can distinguish
${HOMEPATH} vs. ${env.HOMEPATH} as they're clearly 2 different animals, if you will. How else Ant would know what you mean and how're you magically going to reference the system environment w/o "env."?
Even if there was a way to comment out <property environment="env"/>, it's no savings in memory or uncluttering your scripts!
Sorry, I really don't know if there's any other way to refer to system environment values, maybe someone else does?
> Date: Wed, 30 Dec 2009 10:14:14 -0800
> From: Nagendra.Raja@tejasoft.com
> To: user@ant.apache.org
> Subject: RE: Reading environment variables in ant script directly
>
>
> Thank You Rez,
>
> Are u aware of why such explicit approach was taken rather providing the
> environment properties directly.
>
> It would be nice, if ant could consider to provide the environment variables
> implicitly including the conventions you mentioned on prefixing them with
> env.
>
> Regards,
> Raja Nagendra Kumar,
> C.T.O
> www.tejasoft.com
> --
> View this message in context: http://old.nabble.com/Reading-environment-variables-in-ant-script-directly-tp26964622p26970528.html
> Sent from the Ant - Users mailing list archive at Nabble.com.
>
>
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Re: Reading environment variables in ant script directly
Posted by Raja Nagendra Kumar <Na...@tejasoft.com>.
True Antonine.
I clearly understand that using of env is not to be encouraged and ant has a
way to use them with care if one wants.
Infact, our internal Mobile Single Source Build Framework keeps this
principle in very close to keep our self more portable.
However, we still there is a need for access the common boiler plate ant
script or ant properties which should exist on in system folders such
${user.home} or any of the currently exposed ant default properties. It is
just one variable, we need to depend on. Only for such reason, we are doing
a explicit evn property declaration and rest of them are pure ant.
Though it is one line (which is not too bad for us due to limited projects)
for big enterprises with many projects, I was suggesting that why not ant
provide such custom properties though automatic support fetching the
variables though some stand prefix such as evn.xxx etc.
Not sure, if made our point clear to ant developers to see some value of
making by default environment variables available though some standard
prefix, implicitly.
Regards,
Nagendra
antoinell wrote:
>
> Hello Raja,
>
> some ant scripts need access to environment variables but a lot of them
> do not. So this leaves it to each build file developer to decide whether
> he wants his ant property environment to include properties.
>
> Now you can create easily a standard build file that you import
> everywhere and containing the line <property environment="env"/>.
>
> You may end up with other "boilerplate" declarations that you want in
> all your build files.
>
> Regards,
>
> Antoine
>
> Raja Nagendra Kumar wrote:
>> Sure joe, now I understand why we need to give a prefix. Joe, I was
>> looking
>> for why ant did not ant make all the environment variables available
>> through
>> some documented prefix notation rather by default rather than user adding
>> this line in each build script.
>>
>> <property environment="env"/>
>>
>> Regards,
>> Nagendra
>>
>>
>
>
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Re: Reading environment variables in ant script directly
Posted by Antoine Levy Lambert <an...@gmx.de>.
Hello Raja,
some ant scripts need access to environment variables but a lot of them
do not. So this leaves it to each build file developer to decide whether
he wants his ant property environment to include properties.
Now you can create easily a standard build file that you import
everywhere and containing the line <property environment="env"/>.
You may end up with other "boilerplate" declarations that you want in
all your build files.
Regards,
Antoine
Raja Nagendra Kumar wrote:
> Sure joe, now I understand why we need to give a prefix. Joe, I was looking
> for why ant did not ant make all the environment variables available through
> some documented prefix notation rather by default rather than user adding
> this line in each build script.
>
> <property environment="env"/>
>
> Regards,
> Nagendra
>
>
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Re: Reading environment variables in ant script directly
Posted by Raja Nagendra Kumar <Na...@tejasoft.com>.
Sure joe, now I understand why we need to give a prefix. Joe, I was looking
for why ant did not ant make all the environment variables available through
some documented prefix notation rather by default rather than user adding
this line in each build script.
<property environment="env"/>
Regards,
Nagendra
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Re: Reading environment variables in ant script directly
Posted by Joe Schmetzer <jo...@exubero.com>.
2009/12/30 Raja Nagendra Kumar <Na...@tejasoft.com>:
> Are u aware of why such explicit approach was taken rather providing the
> environment properties directly.
>
> It would be nice, if ant could consider to provide the environment variables
> implicitly including the conventions you mentioned on prefixing them with
> env.
Hi Raja,
That approach wouldn't work well with Ant's immutable properites. It
could lead to bugs that were hard to diagnose, and make build scripts
less portable.
For example, consider an ant script that used a property "libdir",
perhaps something like this:
<property name="libdir" location="lib"/>
If Ant were to pick up environment variables directly, if this
particular property was defined in the external environment, then that
definition would take precedence, and the build would probably fail,
although the reason would not be immediatly obvious.
Regards,
Joe Schmetzer
Ant Script Library http://www.exubero.com/asl/
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RE: Reading environment variables in ant script directly
Posted by Raja Nagendra Kumar <Na...@tejasoft.com>.
Thank You Rez,
Are u aware of why such explicit approach was taken rather providing the
environment properties directly.
It would be nice, if ant could consider to provide the environment variables
implicitly including the conventions you mentioned on prefixing them with
env.
Regards,
Raja Nagendra Kumar,
C.T.O
www.tejasoft.com
--
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RE: Reading environment variables in ant script directly
Posted by Rez P <po...@hotmail.com>.
In short, no. You can test it for yourself by writing a simple ant script. All system environment variables have to be preceded by "env.", otherwise, in the example below ${HOMEPATH} by itself is meaningless unless you have assigned a prior value to it. But the minute it's preceded by "env." it knows you're requesting something out of the system environment. If you comment out, <property environment="env"/>, the script will work but ${env.HOMEPATH} will just echo as itself w/o a value.
<project name="test" basedir="." default="test-target">
<target name="test-target">
<property environment="env"/>
<echo>User.Home=${env.HOMEPATH}</echo>
</target>
</project>
> Date: Tue, 29 Dec 2009 22:56:32 -0800
> From: Nagendra.Raja@tejasoft.com
> To: user@ant.apache.org
> Subject: Reading environment variables in ant script directly
>
>
> Hi,
>
> Is it possible to read OS environment variables directly in ant script
> without the line
>
> <property environment="evn"/>
>
> As ant is java and by default all the ant variables would be passed to JRE
> on each java invocation, I am looking for a way to get the value of the
> property variables directly.
>
> Why another line if I could avoid it. Also helps in managing few thing more
> smartly without this call each project.
>
>
> Regards,
> Raja Nagendra Kumar,
> C.T.O
> www.tejasoft.com
> --
> View this message in context: http://old.nabble.com/Reading-environment-variables-in-ant-script-directly-tp26964622p26964622.html
> Sent from the Ant - Users mailing list archive at Nabble.com.
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: user-unsubscribe@ant.apache.org
> For additional commands, e-mail: user-help@ant.apache.org
>
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