user6918: I would like to be able to generate a new seed phrase using:
cardano-wallet recovery-phrase generate

...and use that for a new wallet, but do it offline. So the seed phrase is never onscreen on a network connected machine and only ever recorded on paper.
Is there a documented procedure for doing this?

user4023: The short answer is Yes, you can generate and store your seed phrase offline.
When generating a primary recovery phrase for new Cardano CLI wallet, you can choose 15, 18, 21, or 24-word phrase. Optional additional protection can be provided with a secondary recovery phrase containing 9 or 12 words.
These two Medium stories will provide you with useful information how to do that:
How does 12-word seed phrase work?
Cardano wallet Command Line Interface (Part one)

user252: You can use BIP39 compatible library to generate 15/24 word mnemonics. If looking for CLI, you can use cardano-addresses, check out the Readme in the repo, the command to generate mnemonics would be:
cardano-address recovery-phrase generate --size 15 > phrase.prv

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6918: <p>I would like to be able to generate a new seed phrase using:</p>
<pre><code>cardano-wallet recovery-phrase generate
</code></pre>
<p>...and use that for a new wallet, but do it offline. So the seed phrase is never onscreen on a network connected machine and only ever recorded on paper.</p>
<p>Is there a documented procedure for doing this?</p>
 4023: <p>The short answer is <strong>Yes</strong>, you can generate and store your seed phrase offline.</p>
<p>When generating a <strong>primary recovery phrase</strong> for new Cardano CLI wallet, you can choose 15, 18, 21, or 24-word phrase. Optional additional protection can be provided with a <strong>secondary recovery phrase</strong> containing 9 or 12 words.</p>
<p>These two Medium stories will provide you with useful information how to do that:</p>
<p><a href="https://medium.com/geekculture/cryptocurrency-911-how-does-12-word-seed-phrase-work-9d892de9732" rel="nofollow noreferrer">How does 12-word seed phrase work?</a></p>
<p><a href="https://medium.com/geekculture/cardano-911-wallet-command-line-interface-part-one-ad0ee5ac8509" rel="nofollow noreferrer">Cardano wallet Command Line Interface (Part one)</a></p>
 252: <p>You can use BIP39 compatible library to generate 15/24 word mnemonics. If looking for CLI, you can use <a href="https://github.com/input-output-hk/cardano-addresses" rel="nofollow noreferrer">cardano-addresses</a>, check out the Readme in the repo, the command to generate mnemonics would be:</p>
<pre class="lang-bash prettyprint-override"><code>cardano-address recovery-phrase generate --size 15 &gt; phrase.prv

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</code></pre>
