System Administration tips for Ubuntu
If you've enabled full disk encryption, you will need to enter a password to unlock the disk during boot-up. If you are sitting in front of your desktop, no problem. But if you want to be able to unlock the disk remotely via ssh, and let the system complete boot-up even if you are not in front of the video console, then here are the steps
Host unlock
Hostname 192.168.56.101
User root
IdentityFile /Users/ksa/.ssh/id_rsa_ubuntu_unlock
StrictHostKeyChecking no
If you have a group of 10 or fewer Ubuntu hosts you administer, you can install "Landscape On Premises Edition" in a VM to manage those hosts for free.
In addition to Landscape (or an alternative) is Cockpit which you can use to centrally manage CentOS, RedHat, Fedora, and Ubuntu hosts:
https://www.digitalocean.com/community/tutorials/ubuntu-and-debian-package-management-essentials
https://help.ubuntu.com/lts/serverguide/package-management.html
https://help.ubuntu.com/lts/serverguide/automatic-updates.html
When there's more than one way to perform an action, multiple commands are listed. There is some overlap is these commands. Some are better suited for interactive use and might have enhanced usability features, and others might be better suited to run inside a script. Many of these examples have auto-completion available (tab) for both actions and package names.
If you install a VM using a "server" image, then you can install the desktop related packages (and get a GUI login screen, etc) using 'apt install ubuntu-desktop' or 'apt install ubuntu-gnome-desktop'
| Command | Relevent Pathname | Package Name | Purpose / Notes |
|---|---|---|---|
apt update | update repository metadata | ||
apt upgrade | install all pending updates | ||
apt-cache policy | /etc/apt/sources.list /etc/apt/sources.list.d/ | list repository sources | |
| /var/log/apt/ /var/log/dpkg.log /var/log/aptitude /var/log/unattended-upgrades/ | log file locations relevent to software management | ||
dpkg-query --list | list all installed packages | ||
dpkg-query --listfiles <package-name> | list all files owned by <package-name> | ||
dpkg-query --search <filename-pattern> | find out which installed package owns a filename | ||
apt-file search <filename-pattern> | apt-file | find out which package would install <filename-pattern>. package does not need to be installed already | |
aptitude install <package-name> apt install <package-name> apt-get install <package-name> | aptitude | install <package-name{ tip: use tab completion for actions and package names | |
apt show <package-name> | show details about <package-name>, including repository | ||
debconf-show <package-name> | /var/cache/debconf | show configuration options and current values of <package-name> | |
dpkg-reconfigure <package-name> | reconfigures packages after they have already been installed. | ||
aptitude changelog <package-name> | displays the changelog for <package-name> | ||
aptitude search <package-name-pattern> | search for packages which match <package-name-pattern> | ||
aptitude download <package-name> | downloads the .deb file for the given package to the current directory | ||
aptitude --simulate <action> | print the actions that would normally be performed, but don't | ||
man deb | man page describing deb package format | ||
dpkg-deb --raw-extract <package.deb> <directory> | extracts contents of <package-deb> to <directory>, including the control information files into a DEBIAN subdirectory | ||
apt-cache search meta package | list of all meta packages (a package name that installs a group of other packages) | ||
aptitude search ~o | list of packages which do not have an associated repository (ie, they cannot be downloaded or updated via the standard apt repositories on the host) |
| You may also want to use visual panels to communicate related information, tips or things users need to be aware of. |
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