On 23 November 2022 a new way of installing and using WSL was announced, see <ahref="https://www.theregister.com/2022/11/23/wsl_microsoft_store_default_version/">
Windows Subsystem for Linux now packaged as a Microsoft Store app</a> so some of the documentation on this expo site needs to be revised. <ahref="https://learn.microsoft.com/en-us/windows/wsl/compare-versions?source=recommendations">WSL2 is now noticeably even slower</a> for NTFS files.
<p>WSL now installs as WSL2 by default, but older machines (mostly laptops) may not have the Hyper-V Virtualization hardware and may have to run WSL1.
This is fine: the behaviour is nearly identical so far as an expo laptop is concerned, where you just want to use rsync and scp. An old 2011-era PC has
been doing troggle development happily using WSL1.
<p>For some laptops though, WSL1 does not install properly and you have to use WSL2. The symptom is two error messages when you run <var>dmesg</var> in
the Linux bash terminal window. However, if all you want to use it for is rsync, this may still be fine.
'network' method <var>\\wsl$\Ubuntu-20.04\home\expo\troggle\</var>. This means that file access is somewhat faster too but you probably won't notice. You will need to make sure that your backup/archive methods access this filesystem though.
permissions managed by the filesystem. Every NTFS file that WSL knows about (if mounted with -o metadata) acquires a completely parallel set of file
permissions that are fundamentally different things and are never in sync in any sense. <a
href="https://devblogs.microsoft.com/commandline/chmod-chown-wsl-improvements/">All sorts of fun</a> results. The alternative is to store all your data
in the \\wsl$\ ext4 filesystem (WSL2 only, not WSL1).
<p>If you are disturbed by the instructions to produce an entirely different key for WSL to use when your PC already has a perfectly good PuTTy key installed on the server, then you are right. It is inelegant. But it works, the instructions are shorter and there are fewer things that go wrong. If you are terribly offended by that then you can set your PC up to use one key shared between WSL and normal-Windows as described in <ahref="https://devblogs.microsoft.com/commandline/sharing-ssh-keys-between-windows-and-wsl-2/">this October 2019 article</a>. (Don't set up a password on the key because then you don't need to install keychain.) But beware, this sort of thing goes out of date quite rapidly.
<p>If you have PuTTY installed and working, but you now want to use WSL rsync, you need to set up a key again within the WSL environment. So on a machine with WSL enabled, create an ordinary cmd window and get into the WSL environment using the wsl command:<br/>
The generated key is in the current directory and you need to move them to ~/.ssh/ as is standard on Linux (which is not at all the same place that puTTY uses to keep keys on Windows).
<p>Now you have to complete the <ahref="keyexchange.html">key-pair setup</a> with the new key "id_ras_wsl.pub". But you don't need anyone else's help this time as you can use puTTY to ssh into the server and copy your key to the right place yourself: it is a <ahref="keyexchange.html#secondmachine">"Second Machine"</a>.
<p>
Now finally you can use all the usual command line tools at yor wsl command line to communicate with the server with ssh, scp, rsync, such as:
<p>Having happily used WSL1 in this manner for a couple of years, it was a rude awakening to try this with a new laptop with a small
hard-drive, so all the expo code was re-mounted on a plugged-in SD card. The problem of permissions that seemed to be a WSL2 issue reappeared with
a vengence on WSL1.
<p>The recommended WSL procedure (Jan.2021) said to mount the drive using
<ahref="https://devblogs.microsoft.com/commandline/chmod-chown-wsl-improvements/">a new 'metadata' setting</a>:
<pre><code>sudo umount /mnt/d
sudo mount -t drvfs D: /mnt/d -o metadata,uid=1000,gid=1000,umask=22,fmask=111</code></pre>
<p>This is probably why there is a difference between automatically-mounted drives (e.g. C:, /mnt/c) and plug-in drives:
"<em>By default, WSL will set the uid and gid to the default user with drives that are auto-mounted during instance start. If you mount manually, you will
have to set these explicitly (the default user that gets created when WSL is first installed has a uid=1000 and gid=1000).</em>"
<p>And of course you will need to arrange that this happens automatically whenever you start WSL, so you will need to set
<ahref="https://help.ubuntu.com/community/Fstab"><var>/etc/fstab</var></a>, so ensure that the relevant line says:
<li><ahref="https://www.hanselman.com/blog/CoolWSLWindowsSubsystemForLinuxTipsAndTricksYouOrIDidntKnowWerePossible.aspx">Cool WSL tricks</a> - running Windows commands from WSL environment and running Linux commands from Windows terminal.
<li><ahref="https://code.visualstudio.com/blogs/2019/09/03/wsl2">deep integration</a> - Don't use gitforwindows, install the linux git client in WSL2
<li><ahref="https://blog.anaisbetts.org/using-github-credentials-in-wsl2/">using-github-credentials-in-wsl2</a> - How to use gitforwindows and WSL to connect to GitHub.
</ul>
<p>When things go wrong when trying to sort this out, you may find these pages useful. I did.
<tt><ahref="https://serverfault.com/questions/423075/rsync-failed-to-set-permission-operation-not-permitted">rsync - failed to set permission - operation not permitted</a></tt>
