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FreeBSD操作系统的详细使用手册

href="http://www.FreeBSD.org/cgi/url.cgi?ports/graphics/sane-frontends/pkg-descr"><tt
class="FILENAME">graphics/sane-frontends</tt></a>). The backends part provides access to
the scanner itself. The <b class="APPLICATION">SANE</b>'s <a
href="http://sane-project.org/sane-supported-devices.html" target="_top">supported
devices</a> list specifies which backend will support your image scanner. It is mandatory
to determine the correct backend for your scanner if you want to be able to use your
device. The frontends part provides the graphical scanning interface (<b
class="APPLICATION">xscanimage</b>).</p>

<p>The first thing to do is install the <a
href="http://www.FreeBSD.org/cgi/url.cgi?ports/graphics/sane-backends/pkg-descr"><tt
class="FILENAME">graphics/sane-backends</tt></a> port or package. Then, use the <tt
class="COMMAND">sane-find-scanner</tt> command to check the scanner detection by the <b
class="APPLICATION">SANE</b> system:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">sane-find-scanner -q</kbd>
found SCSI scanner "AGFA SNAPSCAN 600 1.10" at /dev/pass3
</pre>

<p>The output will show the interface type of the scanner and the device node used to
attach the scanner to the system. The vendor and the product model may not appear, it is
not important.</p>

<div class="NOTE">
<blockquote class="NOTE">
<p><b>Note:</b> Some USB scanners require you to load a firmware, this is explained in
the backend manual page. You should also read <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=sane-find-scanner&sektion=1&manpath=FreeBSD+Ports">
<span class="CITEREFENTRY"><span
class="REFENTRYTITLE">sane-find-scanner</span>(1)</span></a> and <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=sane&sektion=7&manpath=FreeBSD+Ports"><span
 class="CITEREFENTRY"><span class="REFENTRYTITLE">sane</span>(7)</span></a> manual
pages.</p>
</blockquote>
</div>

<p>Now we have to check if the scanner will be identified by a scanning frontend. By
default, the <b class="APPLICATION">SANE</b> backends comes with a command line tool
called <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=scanimage&sektion=1&manpath=FreeBSD+Ports">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">scanimage</span>(1)</span></a>.
This command allows you to list the devices and to perform an image acquisition from the
command line. The <var class="OPTION">-L</var> option is used to list the scanner
device:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">scanimage -L</kbd>
device `snapscan:/dev/pass3' is a AGFA SNAPSCAN 600 flatbed scanner
</pre>

<p>No output or a message saying that no scanners were identified indicates that <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=scanimage&sektion=1&manpath=FreeBSD+Ports">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">scanimage</span>(1)</span></a> is
unable to identify the scanner. If this happens, you will need to edit the backend
configuration file and define the scanner device used. The <tt
class="FILENAME">/usr/local/etc/sane.d/</tt> directory contains all backends
configuration files. This identification problem does appear with certain USB
scanners.</p>

<p>For example, with the USB scanner used in the <a
href="scanners.html#SCANNERS-KERNEL-USB">Section 7.6.2.1</a>, <tt
class="COMMAND">sane-find-scanner</tt> gives us the following information:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">sane-find-scanner -q</kbd>
found USB scanner (UNKNOWN vendor and product) at device /dev/uscanner0
</pre>

<p>The scanner is correctly detected, it uses the USB interface and is attached to the
<tt class="FILENAME">/dev/uscanner0</tt> device node. We can now check if the scanner is
correctly identified:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">scanimage -L</kbd>

No scanners were identified. If you were expecting something different,
check that the scanner is plugged in, turned on and detected by the
sane-find-scanner tool (if appropriate). Please read the documentation
which came with this software (README, FAQ, manpages).
</pre>

<p>Since the scanner is not identified, we will need to edit the <tt
class="FILENAME">/usr/local/etc/sane.d/epson.conf</tt> file. The scanner model used was
the <span class="TRADEMARK">EPSON Perfection</span>&reg; 1650, so we know the scanner
will use the <var class="LITERAL">epson</var> backend. Be sure to read the help comments
in the backends configuration files. Line changes are quite simple: comment out all lines
that have the wrong interface for your scanner (in our case, we will comment out all
lines starting with the word <var class="LITERAL">scsi</var> as our scanner uses the USB
interface), then add at the end of the file a line specifying the interface and the
device node used. In this case, we add the following line:</p>

<pre class="PROGRAMLISTING">
usb /dev/uscanner0
</pre>

<p>Please be sure to read the comments provided in the backend configuration file as well
as the backend manual page for more details and correct syntax to use. We can now verify
if the scanner is identified:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">scanimage -L</kbd>
device `epson:/dev/uscanner0' is a Epson GT-8200 flatbed scanner
</pre>

<p>Our USB scanner has been identified. It is not important if the brand and the model do
not match. The key item to be concerned with is the <var
class="LITERAL">`epson:/dev/uscanner0'</var> field, which give us the right backend name
and the right device node.</p>

<p>Once the <tt class="COMMAND">scanimage -L</tt> command is able to see the scanner, the
configuration is complete. The device is now ready to scan.</p>

<p>While <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=scanimage&sektion=1&manpath=FreeBSD+Ports">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">scanimage</span>(1)</span></a>
does allow us to perform an image acquisition from the command line, it is preferable to
use a graphical user interface to perform image scanning. <b class="APPLICATION">SANE</b>
offers a simple but efficient graphical interface: <b class="APPLICATION">xscanimage</b>
(<a href="http://www.FreeBSD.org/cgi/url.cgi?ports/graphics/sane-frontends/pkg-descr"><tt
class="FILENAME">graphics/sane-frontends</tt></a>).</p>

<p><b class="APPLICATION">Xsane</b> (<a
href="http://www.FreeBSD.org/cgi/url.cgi?ports/graphics/xsane/pkg-descr"><tt
class="FILENAME">graphics/xsane</tt></a>) is another popular graphical scanning frontend.
This frontend offers advanced features such as various scanning mode (photocopy, fax,
etc.), color correction, batch scans, etc. Both of these applications are useable as a <b
class="APPLICATION">GIMP</b> plugin.</p>
</div>

<div class="SECT2">
<h2 class="SECT2"><a id="AEN9228" name="AEN9228">7.6.4 Allowing Scanner Access to Other
Users</a></h2>

<p>All previous operations have been done with <tt class="USERNAME">root</tt> privileges.
You may however, need other users to have access to the scanner. The user will need read
and write permissions to the device node used by the scanner. As an example, our USB
scanner uses the device node <tt class="FILENAME">/dev/uscanner0</tt> which is owned by
the <tt class="GROUPNAME">operator</tt> group. Adding the user <tt
class="USERNAME">joe</tt> to the <tt class="GROUPNAME">operator</tt> group will allow him
to use the scanner:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">pw groupmod operator -m <var
class="REPLACEABLE">joe</var></kbd>
</pre>

<p>For more details read the <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=pw&sektion=8"><span
class="CITEREFENTRY"><span class="REFENTRYTITLE">pw</span>(8)</span></a> manual page.</p>

<div class="NOTE">
<blockquote class="NOTE">
<p><b>Note:</b> Of course, for security reasons, you should think twice before adding a
user to any group, especially the <tt class="GROUPNAME">operator</tt> group.</p>
</blockquote>
</div>
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