user112354: Although I've broadcasted many transactions via testnet with RBF opted-in ( --rbf true), yet, given different
incentives present among the miners of the testnet and of the mainnet, my experience so far does not seem very helpful when it comes to grasping firmly how RBF works in Electrum.
So far I've always broadcast them with 1 sat/byte. I most
cases they were picked up by miners with this fee. A couple of times I noticed a slight discrepancy between the fee that I did broadcast (always 1 sat/byte) and the fee (1.2-1.3 sat/byte) that was shown in the blockchain explorer. Such minor discrepancies suggest to me that Electrum somehow automates the process of bumping the fee up when needed.
Does Electrum handle incrementing the fee for me or do I have to manually bump the fee up? If the latter is the case,
can the fee bumping be done from the terminal (i.e. without GUI)?
If the logic of the wallet automates the RBF process, how does it look like exactly? How many blocks does it wait until it increments the fee? By what factor is the fee increased?
I have not found any information that would answer my questions in Electrum's documentation.

user-1: 
A couple of times I noticed a slight discrepancy between the fee that I did broadcast (always 1 sat/byte) and the fee (1.2-1.3 sat/byte) that was shown in the blockchain explorer. Such minor discrepancies suggest to me that Electrum somehow automates the process of bumping the fee up when needed.

Most of the times its above 1 sat/byte (it should be sat/vbyte instead of sat/byte but thats unrelated to question) and you can notice this even in Electrum before broadcasting transaction on top-left in the below screenshot:

If you try different values in fee rate and fee, it will either be below relay fee so not broadcasted or above 1 sat/byte.
Reason:

This rounding can be disabled from preferences:

Now you can use 1 sat/byte fee rate:


Does Electrum handle incrementing the fee for me or do I have to manually bump the fee up?

If a transaction has RBF enabled it can be replaced with another transaction that uses higher fee rate and fee. Right click on any transaction that is not confirmed yet and click on 'increase fee':

Click on OK, sign and broadcast the replacement transaction: 4df6cc117882570b635bf08c28152e5985885227c19ac4cb337532241fdfd087

can the fee bumping be done from the terminal [...]?

Yes bumpfee command can be used which was added in https://github.com/spesmilo/electrum/pull/7438

112354: <p>Although I've broadcasted many transactions via testnet with <a href="https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki" rel="nofollow noreferrer">RBF</a> opted-in ( <code>--rbf true</code>), yet, given different
incentives present among the miners of the testnet and of the mainnet, my experience so far does not seem very helpful when it comes to grasping firmly how RBF works in Electrum.
So far I've always broadcast them with 1 sat/byte. I most
cases they were picked up by miners with this fee. A couple of times I noticed a slight discrepancy between the fee that I did broadcast (always 1 sat/byte) and the fee (1.2-1.3 sat/byte) that was shown in <a href="https://mempool.space/" rel="nofollow noreferrer">the blockchain explorer</a>. Such minor discrepancies suggest to me that <a href="https://electrum.org/" rel="nofollow noreferrer">Electrum</a> somehow automates the process of bumping the fee up when needed.</p>
<p>Does Electrum handle incrementing the fee for me or do I have to manually bump the fee up? If the latter is the case,
can the fee bumping be done from the terminal (i.e. without <a href="https://en.wikipedia.org/wiki/Graphical_user_interface" rel="nofollow noreferrer">GUI</a>)?
If the logic of the wallet automates the RBF process, how does it look like exactly? How many blocks does it wait until it increments the fee? By what factor is the fee increased?
I have not found any information that would answer my questions in <a href="https://electrum.readthedocs.io/en/latest/" rel="nofollow noreferrer">Electrum's documentation</a>.</p>
 -1: <blockquote>
<p>A couple of times I noticed a slight discrepancy between the fee that I did broadcast (always 1 sat/byte) and the fee (1.2-1.3 sat/byte) that was shown in the blockchain explorer. Such minor discrepancies suggest to me that Electrum somehow automates the process of bumping the fee up when needed.</p>
</blockquote>
<p>Most of the times its above 1 sat/byte (<em>it should be sat/vbyte instead of sat/byte but thats unrelated to question</em>) and you can notice this even in Electrum before broadcasting transaction on top-left in the below screenshot:</p>
<p><a href="https://i.stack.imgur.com/l2BKz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/l2BKz.png" alt="fee-rate-electrum" /></a></p>
<p>If you try different values in fee rate and fee, it will either be below relay fee so not broadcasted or above 1 sat/byte.</p>
<p>Reason:</p>
<p><a href="https://i.stack.imgur.com/aVtAF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/aVtAF.png" alt="rounding" /></a></p>
<p>This rounding can be disabled from preferences:</p>
<p><a href="https://i.stack.imgur.com/PX3mC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PX3mC.png" alt="preferences" /></a></p>
<p>Now you can use 1 sat/byte fee rate:</p>
<p><a href="https://i.stack.imgur.com/3yPIe.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3yPIe.png" alt="1-sat-fee-rate" /></a></p>
<blockquote>
<p>Does Electrum handle incrementing the fee for me or do I have to manually bump the fee up?</p>
</blockquote>
<p>If a transaction has RBF enabled it can be replaced with another transaction that uses higher fee rate and fee. Right click on any transaction that is not confirmed yet and click on 'increase fee':</p>
<p><a href="https://i.stack.imgur.com/rOMXt.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rOMXt.png" alt="RBF" /></a></p>
<p>Click on OK, sign and broadcast the replacement transaction: <a href="https://tbtc.bitaps.com/4df6cc117882570b635bf08c28152e5985885227c19ac4cb337532241fdfd087" rel="nofollow noreferrer"><code>4df6cc117882570b635bf08c28152e5985885227c19ac4cb337532241fdfd087</code></a></p>
<blockquote>
<p>can the fee bumping be done from the terminal [...]?</p>
</blockquote>
<p>Yes <code>bumpfee</code> command can be used which was added in <a href="https://github.com/spesmilo/electrum/pull/7438" rel="nofollow noreferrer">https://github.com/spesmilo/electrum/pull/7438</a></p>
