[CMake] Test if ENV${VAR} is set

[Davis Ford]

Thanks to all for the feedback / suggestions.

I did edit the wiki -- feel free to revise my submission or extend with
your own.  I linked to this thread on there, as well.

http://www.itk.org/Wiki/CMake/Examples#Check_if_environment_variable_is_set

On Fri, Sep 14, 2012 at 4:43 PM, Bogdan Cristea <cristeab at gmail.com> wrote:

> On Friday 14 September 2012 16:26:10 you wrote:
> > On Fri, Sep 14, 2012 at 4:17 PM, Bogdan Cristea <cristeab at gmail.com>
> wrote:
> > > On Friday 14 September 2012 16:13:16 Davis Ford wrote:
> > >> if("$ENV{FOO_HOME}" MATCHES "")
> > >>
> > >>    message("You must set FOO_HOME")
> > >>    return()
> > >>
> > >> endif()
> > >
> > > Try something like this
> > >
> > > if(NOT ENV{FOO_HOME})
> > > message("etc")
> > > endif()
> > >
> > > --
> > > Bogdan
> > > --
> > >
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> > >
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> >
> > I would use the double quotes like you had originally, but use
> > STREQUAL instead of MATCHES. Or use MATCHES "^$" to match ONLY the
> > explicitly empty string, because MATCHES "" basically matches
> > everything because everything "contains" the empty string...
> >
> > HTH,
> > David
>
> I have tested and this should work
>
> set(VAR $ENV{FOO_VAR})
> if (NOT VAR)
>   message("Cannot find FOO_VAR")
> endif()
>
> For some reason, when I use directly
> if (NOT ENV{FOO_VAR})
> does not seem to work.
>
> --
> Bogdan Cristea
> Software Engineer
> tel: +33 (0)6 21 64 15 81
>       +33 (0)6 26 74 98 19
> personal site: http://sites.google.com/site/cristeab/
> --
>
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the CMake FAQ at:
> http://www.cmake.org/Wiki/CMake_FAQ
>
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