<div dir="ltr"><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></div><div></div></div><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">even.rouault@spatialys.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
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<p>Andrew,<br>
</p>
<br>
<blockquote type="cite">
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<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>
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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">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">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">http://www.spatialys.com</a>
My software is free, but my time generally not.</pre>
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