Cockpit uses the PackageKit D-Bus API to get information about available package updates and to apply them, in an Operating System independent manner.
To perform similar tasks from the command line, use the pkcon command:
$ pkcon refresh
$ pkcon get-updates
Available sudo-1.8.20p2-1.fc26.x86_64 (updates-testing)
Allows restricted root access for specified users
Available vim-filesystem-2:8.0.617-1.fc26.x86_64 (updates-testing)
VIM filesystem layout
Available vim-minimal-2:8.0.617-1.fc26.x86_64 (updates-testing)
A minimal version of the VIM editor
$ pkcon get-update-detail sudo
Details about the update:6.x86_64 [fedora]
Package: sudo-1.8.20p2-1.fc26.x86_64
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1452941
Update text: - update to 1.8.20p2
- added sudo package to dnf/yum protected packages
$ pkcon update
The following packages have to be updated:
sudo-1.8.20p2-1.fc26.x86_64 Allows restricted root access for specified users
vim-filesystem-2:8.0.617-1.fc26.x86_64 VIM filesystem layout
vim-minimal-2:8.0.617-1.fc26.x86_64 A minimal version of the VIM editor
Proceed with changes? [N/y] y
[...]
Of course you can also use your Operating System specific commands for
that, such as dnf updateinfo info on Fedora or sudo apt upgrade
on Debian.