====== Update Raspbian ======
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To upgrade and update Raspbian, enter the following from the command line:
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   sudo apt-get update && sudo apt-get upgrade -y 
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The <color Red>-y</color> means you don't have to say 'yes' to any Yes/No questions.
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==== Update Firmware =====
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    sudo apt-get install rpi-update
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===== Automatic Updates =====
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If you want to automate these procedures it can be done by configuring apt's Periodic options. The Raspberry Pi comes with apt installed (it provides the apt-get commands, etc.), and as part of that package an automated script is installed (in /etc/cron.daily/apt) for doing automated updates on a daily basis (using the cron daemon). These may be controlled by creating (as root) a file /etc/apt/apt.conf.d/10periodic putting the following into it:
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<file>
APT::Periodic::Update-Package-Lists "1";
APT::Periodic::Download-Upgradeable-Packages "0";
APT::Periodic::AutocleanInterval "0";
APT::Periodic::Unattended-Upgrade "0";
</file>
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This configuration will just run update every day for you so when you run sudo apt-get upgrade you'll install the latest packages (without having to first run apt-get update).
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===== Automatic Upgrades =====
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To configure apt to automatically upgrade packages as well - firstly you'll need to install a new package to make the unattended upgrades work:

<file>
sudo apt-get install unattended-upgrades
</file>
Then you change the following option to "1" in /etc/apt/apt.conf.d/10periodic to enable automated upgrades:

<file>
APT::Periodic::Unattended-Upgrade "1";
</file>
For more details see the comments inside the /etc/cron.daily/apt and then put the relevant options into the /etc/apt/apt.conf.d/10periodic file.