Using the installer to flash the kernel again

<p>

Every once in a while someone asks how they can use the Debian installer
to access their system on disk to run commands, for example to write
the kernel and ramdisk to flash again.  This is particularly useful on
headless NAS devices.  So here's how to do it:

</p>

<ol>

<li>Start the Debian installer.</li>

<li>Remove the SSH key from <tt>~/.known_hosts</tt> because the installer
will always generate a new key.</li>

<li>Connect to the installer with SSH: <tt>ssh installer@...</tt></li>

<li>Follow the installer until you reach the partitioner, then choose "go
back".</li>

<li>Open a shell (look for <tt>Execute a shell</tt> towards the end of the
menu).</li>

<li>Run the commands below (the example assumes that <tt>/boot</tt> is
<tt>/dev/sda1</tt> and <tt>/</tt> is <tt>/dev/sda2</tt>.</li>

</ol>

<div class="code">
<pre>
mkdir -p /target
mount /dev/sda2 /target
mount /dev/sda1 /target/boot
mount --bind /dev /target/dev
mount -t proc none /target/proc
mount -t sysfs none /target/sys
chroot /target /bin/sh
# the prompt will change
# make modifications to the system and regenerate the initramfs
update-initramfs -u
exit
# the prompt will change again as you're leaving the chroot
umount /target/sys
umount /target/proc
umount /target/dev
umount /target/boot
umount /target
reboot
</pre>
</div>

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