[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: How can I check an environment variable?
|
From: |
Eric Blake |
|
Subject: |
Re: How can I check an environment variable? |
|
Date: |
Wed, 12 Aug 2009 07:26:28 -0600 |
|
User-agent: |
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.22) Gecko/20090605 Thunderbird/2.0.0.22 Mnenhy/0.7.6.666 |
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
According to Dr. David Kirkby on 8/12/2009 3:18 AM:
> What's the best way to check if an environment variable is set?
See AC_ARG_VAR,
http://www.gnu.org/software/autoconf/manual/autoconf.html#Setting-Output-Variables,
for how to treat SAGE_USE_BROKEN_TOOLS as a precious variable.
> I want
> to allow a user to set an environment variable
>
> $ SAGE_USE_BROKEN_TOOLS=yes
> $ export SAGE_USE_BROKEN_TOOLS
>
> then the configure script check if SAGE_USE_BROKEN_TOOLS is set to 'yes'
> or not and behave differently whether or not it is set.
Ultimately, you should teach your users to prefer:
./configure SAGE_USE_BROKEN_TOOLS=yes
rather than your approach of:
export SAGE_USE_BROKEN_TOOLS=yes
./configure
as the former will remember the user's choice at the time of the configure
even if they subsequently change their environment.
- --
Don't work too hard, make some time for fun as well!
Eric Blake address@hidden
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (Cygwin)
Comment: Public key at home.comcast.net/~ericblake/eblake.gpg
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
iEYEARECAAYFAkqCwwQACgkQ84KuGfSFAYBxRgCgxcPUPNnxBAXWR5d90QnUCTlY
TSMAnizTtpziz/b3qVAWkBptDF8efRHG
=/hB0
-----END PGP SIGNATURE-----