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Why does the separation of update and upgrade even exist?
February 13, 2018
Edited: June 12, 2020
November 24, 2022
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They do separate things for many reasons.
One example is a question I posted and self-answered: How can PPAs be removed using GUI?. On this screen we want to remove PPAs not upgrade the software:
After removing a PPA the GUI software automatically runs
sudo apt update. If you were to remove a PPA from the command line you need to run
sudo apt update after removing a PPA from sources list.
Without a separate
apt update function there is no way to remove a PPA!.
Another example is you need to run
sudo apt update from command line to refresh sources. Then you can find out what could be upgraded without actually upgrading:
$ apt list --upgradable Listing... Done conky-std/xenial 1.10.1-3 amd64 [upgradable from: 1.9.0-4] google-chrome-stable/stable 65.0.3325.181-1 amd64 [upgradable from: 63.0.3239.132-1] libxnvctrl0/xenial 390.48-0ubuntu0~gpu16.04.1 amd64 [upgradable from: 387.22-0ubuntu0~gpu16.04.1] nvidia-settings/xenial 390.48-0ubuntu0~gpu16.04.1 amd64 [upgradable from: 387.22-0ubuntu0~gpu16.04.1] peek/xenial 1.3.1-0~ppa23~ubuntu16.04.1 amd64 [upgradable from: 1.2.1-0~ppa20~ubuntu16.04.1]
Looking at the output you could decide to have a given package “pinned” or “held back” and not upgraded the next time `sudo apt upgrade” is run. If there were a single “update/upgrade” process you would loose these ability.