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<div class="moz-cite-prefix">Le 04/10/2024 à 18:06, Andrew Plowright
a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CAOHs3k1bY1bcHHtAJo9RWEAMUihymSNFFSLOS9jRjJKShLQ_Uw@mail.gmail.com">
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<div>Thanks again Even and Fernando, you've both provided a lot
of helpful information that has turned this into a very
instructive Linux learning opportunity. <br>
</div>
<div><br>
</div>
<div>Even: can I confirm that, in the third option you suggested
(the "less ugly alternative"), this would involve:</div>
<div><br>
</div>
<div>1. Installing QGIS using Software Manager (or any other
way, just not necessarily building it from source)</div>
<div>2. Building a second instance of GDAL from source which has
the same version as whatevever GDAL version is created by the
QGIS installation (ex.: 3.8.4) and which is built with the Mr
Sid driver.<br>
</div>
<div>3. This second instance of GDAL is given its own secluded
/opt/gdal_3_8_4 folder to keep it separate from /usr</div>
<div>4. Setting GDAL_DRIVER_PATH will make GDAL search
/opt/gdal_3_8_4/lib/gdalplugins for additional plugins, such
as the MrSid driver. This should affect any instance of GDAL,
whether I'm running it through QGIS or through the command
line?</div>
<div><br>
</div>
<div>Did I get all that correct?<br>
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yes<br>
<blockquote type="cite"
cite="mid:CAOHs3k1bY1bcHHtAJo9RWEAMUihymSNFFSLOS9jRjJKShLQ_Uw@mail.gmail.com"><br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sat, Sep 28, 2024 at
10:33 AM Even Rouault <<a
href="mailto:even.rouault@spatialys.com"
moz-do-not-send="true" class="moz-txt-link-freetext">even.rouault@spatialys.com</a>>
wrote:<br>
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style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p>Andrew,<br>
</p>
<br>
<blockquote type="cite">
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<div>
<div>
<div>
<div>
<div style="margin-left:40px">$ ldd
/bin/qgis.bin | grep gdal<br>
</div>
</div>
<div><br>
<div style="margin-left:40px">libgdal.so.34
=> /lib/x86_64-linux-gnu/libgdal.so.34
(0x00007a0581a00000)<br>
</div>
<br>
</div>
But I'm not sure what to do with that information.<br>
</div>
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</blockquote>
<p> /lib/x86_64-linux-gnu/libgdal.so.34 is the version of
GDAL that comes with package manager, so 3.8.4 here</p>
<p>I'm not sure how you are familiar with the dynamic
linking concepts and tools, but if you're not, reading
<a
href="https://opensource.com/article/22/5/dynamic-linking-modular-libraries-linux"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">https://opensource.com/article/22/5/dynamic-linking-modular-libraries-linux</a>
or related resources on dynamic linking might help you
understand why those seemlingly "weird" behaviors are
totally explainable. Takes time, and even with experience,
mixing up several versions of a library on a system and
being confused is not uncommon</p>
<p>I'm going to hate myself for the below suggestion, and
you probably too when it will hit you back in the face (so
forget I've told you about it ;-), ... but ... to quickly
workaround your issue, you can do:<br>
</p>
<p>sudo ln -s /usr/lib/libgdal.so.35 /usr/lib/libgdal.so.34
# i'm already hating myself</p>
<p>sudo mv /lib/x86_64-linux-gnu/libgdal.so.34
/lib/x86_64-linux-gnu/libgdal.so.34.disabled # I'm
hating myself even more... <br>
</p>
<p>And now launch QGIS.... As GDAL keeps a backwards
compatible C ABI, this ugly substitution of the expected
GDAL 3.8.4 version at build time is supposed to (mostly)
work. That said, you might run in occasional bugs, where
QGIS tries to workaround GDAL specific bug, based on the
version of GDAL QGIS was built against...</p>
<p>OK, I believe you've been sufficienly warned this is
*not* the normal way of proceeding, just a quick&dirty
workaround<br>
</p>
<p>To undo the above mess:</p>
<p>sudo mv /lib/x86_64-linux-gnu/libgdal.so.34.disabled
/lib/x86_64-linux-gnu/libgdal.so.34</p>
<p>sudo mv /usr/lib/libgdal.so.34
/usr/lib/libgdal.so.34.disabled (i'm always nervous doing
a rm in /usr territory, so I tend to just rename ...)<br>
</p>
<p>The clean solution would be that you rebuild QGIS against
your installed GDAL, but that would be for another
episode. Another friendly advice would be that when doing
a custom build you don't do CMAKE_INSTALL_PREFIX=/opt ,
but here something like
CMAKE_INSTALL_PREFIX=/opt/gdal_3_10_master to avoid
messing with /usr which should be only the territory of
your package manager tool.</p>
<p><br>
</p>
<p>Another less ugly alternative would be that you download
<a
href="http://download.osgeo.org/gdal/3.8.4/gdal-3.8.4.tar.gz"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">http://download.osgeo.org/gdal/3.8.4/gdal-3.8.4.tar.gz</a>,
build it with support of the MrSID driver as a plugin,
with -DGDAL_ENABLE_DRIVER_MRSID_PLUGIN=ON, install it in
/opt/gdal_3_8_4, and then just set the
GDAL_DRIVER_PATH=/opt/gdal_3_8_4/lib/gdalplugins
environment variable. That way you would use the system
GDAL library with just the addition of the MrSID driver.</p>
<p>Actually that might not be terribly harder to do than my
above hacks, so I'm definitely encouraging you to explore
that way</p>
<p>And ... you should know that the company behind the MrSID
SDK has declared they won't ever release any new binary
version of it. This means that at most in a few years,
this SDK will likely be totally unusable on modern
systems. So everyone using SID files had better convert
them to something else, like COG, when they still have a
chance...</p>
<p>/me taking a passport to an undisclosed country without
extradition <span lang="en"><span><span>agreement.</span></span></span></p>
Even
<pre cols="72">--
<a href="http://www.spatialys.com" target="_blank"
moz-do-not-send="true" class="moz-txt-link-freetext">http://www.spatialys.com</a>
My software is free, but my time generally not.</pre>
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</blockquote>
<pre class="moz-signature" cols="72">--
<a class="moz-txt-link-freetext" href="http://www.spatialys.com">http://www.spatialys.com</a>
My software is free, but my time generally not.</pre>
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