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From: Wang Xuerui <idontknw.wang@gmail.com>
Date: Thu, 19 Sep 2013 23:35:34 +0800
Message-ID: <CABK5mSYE_Rez2S6KseMdW0JV=ei=cp26Vdm4x3AgjvK9CzOUJQ@mail.gmail.com>
Subject: Re: [gentoo-user] Switching off a long list of USE flags
To: gentoo-user@lists.gentoo.org
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2013/9/19 gevisz <gevisz@gmail.com>:
> I would like to build sane-backend only for one specific scanner.
>
> However, there are a huge lot of different USE flags for other scanners
> that are already switched on by default.
>
> Is there any easy way to switch them off?
>
> Something like:
>
>           media-gfx/sane-backends -sane_backends* sane_backends_hp
>
> Exactly that way does not work, but may be something like that...
>
> ...instead of directly switching off every one of them.

According to the Package Manager Specification, the variable should
not be incremental, i.e. any value set would override *any* defaults
or previously set values. So just do SANE_BACKENDS="xxx" in your
make.conf, same as what you'd do for VIDEO_CARDS and the like.

Hope it helps :)