Ubuntu Server

https://ubuntu.com/server/docs/
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### Install package with --snapshot option

Source: https://ubuntu.com/server/docs/how-to/software/snapshot-service

Quick start example: install hello using a snapshot timestamp. The --snapshot option is passed to apt followed by a UTC timestamp in YYYYMMDDTHHMMSSZ format.

```bash
sudo apt install hello --update --snapshot 20240301T030400Z
```

--------------------------------

### Install DOCA-OFED generic metapackage example

Source: https://ubuntu.com/server/docs/how-to/networking/install-doca-ofed

Example installation when uname -r returns 6.17.0-20-generic.

```bash
$ sudo apt install -y doca-ofed-generic
```

--------------------------------

### Install and start NFS server

Source: https://ubuntu.com/server/docs/how-to/networking/install-nfs

Install the NFS server package and start the NFS server service.

```bash
sudo apt install nfs-kernel-server
```

```bash
sudo systemctl start nfs-kernel-server.service
```

--------------------------------

### Install MySQL server with apt

Source: https://ubuntu.com/server/docs/how-to/databases/install-mysql

Installs the MySQL server package. After installation, the MySQL server should start automatically.

```bash
sudo apt install mysql-server
```

--------------------------------

### APT install output for apache2

Source: https://ubuntu.com/server/docs/tutorial/managing-software

Example output from the apt install apache2 command, showing the packages to be installed, dependencies, suggested packages, and a summary. The prompt 'Continue? [Y/n]' appears at the end.

```text
Installing:                     
  apache2

Installing dependencies:
  apache2-bin    libapr1t64               libaprutil1t64
  apache2-data   libaprutil1-dbd-sqlite3  liblua5.4-0
  apache2-utils  libaprutil1-ldap         ssl-cert

Suggested packages:
  apache2-doc  apache2-suexec-pristine  | apache2-suexec-custom  www-browser

Summary:
  Upgrading: 0, Installing: 10, Removing: 0, Not Upgrading: 0
  Download size: 2116 kB
  Space needed: 8218 kB / 1328 MB available

Continue? [Y/n] 
```

--------------------------------

### Install CUPS with apt

Source: https://ubuntu.com/server/docs/how-to/networking/cups-print-server

Run this command in the terminal to perform a basic installation of CUPS. It installs CUPS and its dependencies, and the server starts automatically after installation.

```bash
sudo apt install cups
```

--------------------------------

### Start virtiofsd

Source: https://ubuntu.com/server/docs/explanation/virtualisation/qemu-microvm

Installs virtiofsd and starts it with a socket path and shared directory, waiting for a vhost-user socket connection.

```bash
sudo apt install virtiofsd
```

```bash
/usr/libexec/virtiofsd --socket-path=/tmp/vfsd.sock --shared-dir /tmp/chiselled-hello
```

```text
...
[INFO  virtiofsd] Waiting for vhost-user socket connection...
```

--------------------------------

### Open vSwitch DPDK startup log

Source: https://ubuntu.com/server/docs/how-to/networking/dpdk-with-open-vswitch

Example output from starting Open vSwitch with DPDK support. Shows systemd and ovs-ctl messages, EAL initialization, PCI device probing, and the default vhost_sock_dir of /var/run/openvswitch when -vhost_sock_dir is not provided.

```text
systemd[1]: Stopping Open vSwitch...
systemd[1]: Stopped Open vSwitch.
systemd[1]: Stopping Open vSwitch Internal Unit...
ovs-ctl[3541]: * Killing ovs-vswitchd (3329)
ovs-ctl[3541]: * Killing ovsdb-server (3318)
systemd[1]: Stopped Open vSwitch Internal Unit.
systemd[1]: Starting Open vSwitch Internal Unit...
ovs-ctl[3560]: * Starting ovsdb-server
ovs-vsctl: ovs|00001|vsctl|INFO|Called as ovs-vsctl --no-wait -- init -- set Open_vSwitch . db-version=7.12.1
ovs-vsctl: ovs|00001|vsctl|INFO|Called as ovs-vsctl --no-wait set Open_vSwitch . ovs-version=2.5.0 "external-ids:system-id=\"e7c5ba80-bb14-45c1-b8eb-628f3ad03903\"" "system-type=\"Ubuntu\"" "system-version=\"16.04-xenial\""
ovs-ctl[3560]: * Configuring Open vSwitch system IDs
ovs-ctl[3560]: 2016-01-22T08:58:31Z|00001|dpdk|INFO|No -vhost_sock_dir provided - defaulting to /var/run/openvswitch
ovs-vswitchd: ovs|00001|dpdk|INFO|No -vhost_sock_dir provided - defaulting to /var/run/openvswitch
ovs-ctl[3560]: EAL: Detected lcore 0 as core 0 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 1 as core 1 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 2 as core 2 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 3 as core 3 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 4 as core 4 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 5 as core 5 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 6 as core 0 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 7 as core 1 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 8 as core 2 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 9 as core 3 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 10 as core 4 on socket 0
ovs-ctl[3560]: EAL: Detected lcore 11 as core 5 on socket 0
ovs-ctl[3560]: EAL: Support maximum 128 logical core(s) by configuration.
ovs-ctl[3560]: EAL: Detected 12 lcore(s)
ovs-ctl[3560]: EAL: VFIO modules not all loaded, skip VFIO support...
ovs-ctl[3560]: EAL: Setting up physically contiguous memory...
ovs-ctl[3560]: EAL: Ask a virtual area of 0x100000000 bytes
ovs-ctl[3560]: EAL: Virtual area found at 0x7f2040000000 (size = 0x100000000)
ovs-ctl[3560]: EAL: Requesting 4 pages of size 1024MB from socket 0
ovs-ctl[3560]: EAL: TSC frequency is ~2397202 KHz
ovs-vswitchd[3592]: EAL: TSC frequency is ~2397202 KHz
ovs-vswitchd[3592]: EAL: Master lcore 0 is ready (tid=fc6cbb00;cpuset=[0])
ovs-vswitchd[3592]: EAL: PCI device 0000:04:00.0 on NUMA socket 0
ovs-vswitchd[3592]: EAL:   probe driver: 8086:1528 rte_ixgbe_pmd
ovs-vswitchd[3592]: EAL:   Not managed by a supported kernel driver, skipped
ovs-vswitchd[3592]: EAL: PCI device 0000:04:00.1 on NUMA socket 0
ovs-vswitchd[3592]: EAL:   probe driver: 8086:1528 rte_ixgbe_pmd
ovs-vswitchd[3592]: EAL:   PCI memory mapped at 0x7f2140000000
ovs-vswitchd[3592]: EAL:   PCI memory mapped at 0x7f2140200000
ovs-ctl[3560]: EAL: Master lcore 0 is ready (tid=fc6cbb00;cpuset=[0])
ovs-ctl[3560]: EAL: PCI device 0000:04:00.0 on NUMA socket 0
ovs-ctl[3560]: EAL:   probe driver: 8086:1528 rte_ixgbe_pmd
ovs-ctl[3560]: EAL:   Not managed by a supported kernel driver, skipped
ovs-ctl[3560]: EAL: PCI device 0000:04:00.1 on NUMA socket 0
ovs-ctl[3560]: EAL:   probe driver: 8086:1528 rte_ixgbe_pmd
ovs-ctl[3560]: EAL:   PCI memory mapped at 0x7f2140000000
ovs-ctl[3560]: EAL:   PCI memory mapped at 0x7f2140200000
ovs-vswitchd[3592]: PMD: eth_ixgbe_dev_init(): MAC: 4, PHY: 3
ovs-vswitchd[3592]: PMD: eth_ixgbe_dev_init(): port 0 vendorID=0x8086 deviceID=0x1528
ovs-ctl[3560]: PMD: eth_ixgbe_dev_init(): MAC: 4, PHY: 3
ovs-ctl[3560]: PMD: eth_ixgbe_dev_init(): port 0 vendorID=0x8086 deviceID=0x1528
ovs-ctl[3560]: Zone 0: name:<RG_MP_log_history>, phys:0x83fffdec0, len:0x2080, virt:0x7f213fffdec0, socket_id:0, flags:0
ovs-ctl[3560]: Zone 1: name:<MP_log_history>, phys:0x83fd73d40, len:0x28a0c0, virt:0x7f213fd73d40, socket_id:0, flags:0
ovs-ctl[3560]: Zone 2: name:<rte_eth_dev_data>, phys:0x83fd43380, len:0x2f700, virt:0x7f213fd43380, socket_id:0, flags:0
ovs-ctl[3560]: * Starting ovs-vswitchd
ovs-ctl[3560]: * Enabling remote OVSDB managers
systemd[1]: Started Open vSwitch Internal Unit.
systemd[1]: Starting Open vSwitch...
systemd[1]: Started Open vSwitch.
```

--------------------------------

### Install nginx with apt

Source: https://ubuntu.com/server/docs/how-to/web-services/install-nginx

Updates the package list and installs nginx along with required dependencies and common modules, then starts the nginx web server.

```bash
sudo apt update && sudo apt install nginx
```

--------------------------------

### Interactive network configuration prompt for live server installation

Source: https://ubuntu.com/server/docs/how-to/installation/interactive-live-server-installation-on-ibm-z-vm-s390x

Interactive network configuration prompt when no parmfile is set. It asks to enable interactive netboot, select a qeth device, choose static or DHCP IP configuration, and specify the URL of the installer ISO. The example uses static IP 10.222.111.24 and an FTP URL.

```text
Attempt interactive netboot from a URL? 
yes no (default yes): yes
Available qeth devices: 
0.0.0600 0.0.0603 
zdev to activate (comma separated, optional): 0600
QETH device 0.0.0600:0.0.0601:0.0.0602 configured 
Two methods available for IP configuration: 
  * static: for static IP configuration 
  * dhcp: for automatic IP configuration 
static dhcp (default 'dhcp'): static
ip: 10.222.111.24
gateway (default 10.222.111.1): .
dns (default .): 
vlan id (optional): 
 http://cdimage.ubuntu.com/ubuntu/releases/20.04.5/release/ubuntu-20.04.5-live-server-s390x.iso (default) 
url: ftp://10.11.12.2:21/ubuntu-live-server-20.04.5/ubuntu-20.04.5-live-server-s390x.iso
http_proxy (optional):  
```

--------------------------------

### Boot VM from live ISO with qemu-system-x86_64

Source: https://ubuntu.com/server/docs/how-to/virtualisation/qemu

Boots a VM directly from a live ISO with 4G RAM and KVM acceleration. This example is for illustration only; verify checksums before use. On headless systems, specify an alternative display method such as VNC.

```bash
qemu-system-x86_64 -m 4G -enable-kvm -cdrom http://releases.ubuntu.com/noble/ubuntu-24.04.3-live-server-amd64.iso
```

--------------------------------

### Launch Multipass VM with 'multipass launch resolute --name tutorial'

Source: https://ubuntu.com/server/docs/tutorial/cli-in-depth

Launches a new Ubuntu 26.04 LTS (resolute) virtual machine named 'tutorial' using Multipass. Requires Multipass to be installed and a terminal window open. Downloads the most recent daily image and may take some time depending on internet speed.

```bash
multipass launch resolute --name tutorial
```

--------------------------------

### Install and configure Open vSwitch with DPDK

Source: https://ubuntu.com/server/docs/how-to/networking/dpdk-with-open-vswitch

Commands to install the openvswitch-switch-dpdk package, set the DPDK vswitchd alternative, and initialize DPDK. Also includes optional commands to run on core 0 only, allocate 2G huge pages, and limit to one allowlisted device. After configuration, restart the service.

```bash
sudo apt-get install openvswitch-switch-dpdk
```

```bash
sudo update-alternatives --set ovs-vswitchd /usr/lib/openvswitch-switch-dpdk/ovs-vswitchd-dpdk
```

```bash
ovs-vsctl set Open_vSwitch . "other_config:dpdk-init=true"
```

```bash
ovs-vsctl set Open_vSwitch . "other_config:dpdk-lcore-mask=0x1"
```

```bash
ovs-vsctl set Open_vSwitch . "other_config:dpdk-alloc-mem=2048"
```

```bash
ovs-vsctl set Open_vSwitch . "other_config:dpdk-extra=--pci-whitelist=0000:04:00.0"
```

```bash
sudo service openvswitch-switch restart
```

--------------------------------

### List sample configuration files

Source: https://ubuntu.com/server/docs/how-to/security/install-openvpn

Shows the paths to the sample client and server configuration files included with the OpenVPN installation.

```text
/usr/share/doc/openvpn/examples/sample-config-files/client.conf
/usr/share/doc/openvpn/examples/sample-config-files/server.conf
```

--------------------------------

### Install kpropd daemon

Source: https://ubuntu.com/server/docs/how-to/kerberos/set-up-secondary-kdc

Installs the kpropd daemon, which listens for connections from the kprop utility on the primary KDC. The service starts immediately after installation.

```bash
sudo apt install krb5-kpropd
```

--------------------------------

### Install virtualization packages with apt

Source: https://ubuntu.com/server/docs/how-to/virtualisation/intel-tdx

Installs qemu-system-x86, ovmf-inteltdx, libvirt-daemon-system, and libvirt-clients. Run as root or with sudo.

```bash
sudo apt update
sudo apt install \
  qemu-system-x86 \
  ovmf-inteltdx \
  libvirt-daemon-system \
  libvirt-clients
```

--------------------------------

### Provisioning Output Example

Source: https://ubuntu.com/server/docs/how-to/samba/provision-samba-ad-controller

Example output from the provisioning command, with long lines truncated. Shows the server role, hostname, NetBIOS domain, DNS domain, and domain SID.

```text
INFO ... #498: Server Role:     active directory domain controller
INFO ... #499: Hostname:        ad
INFO ... #500: NetBIOS Domain:  EXAMPLE
INFO ... #501: DNS Domain:      example.internal
INFO ... #502: DOMAIN SID:      S-1-5-21-2373640847-2123283686-338028823
```

--------------------------------

### Install krb5-user package

Source: https://ubuntu.com/server/docs/how-to/security/openssh-gssapi

Install the krb5-user package to get the kadmin tool. During installation, you will be prompted for the Kerberos realm and KDC/Admin server hostnames.

```bash
sudo apt install krb5-user
```

--------------------------------

### Set up legacy boot files

Source: https://ubuntu.com/server/docs/how-to/installation/how-to-netboot-the-server-installer-on-amd64

Commands to download pxelinux and configure the legacy boot environment.

```bash
wget http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/legacy-images/netboot/pxelinux.0
> mkdir -p /srv/tftp
> mv pxelinux.0 /srv/tftp/
```

```bash
cp /usr/lib/syslinux/modules/bios/ldlinux.c32 /srv/tftp/
```

--------------------------------

### Install libnss3-tools

Source: https://ubuntu.com/server/docs/explanation/crypto/network-security-services-nss

Installs the libnss3-tools package, which provides the certutil and tstclnt utilities used in the examples.

```bash
sudo apt install libnss3-tools
```

--------------------------------

### Install QEMU with apt-get

Source: https://ubuntu.com/server/docs/how-to/virtualisation/qemu

Installs QEMU on Ubuntu. Run after confirming KVM support with kvm-ok.

```bash
sudo apt-get install qemu-system
```

--------------------------------

### Install debug symbols for xserver-xorg-core

Source: https://ubuntu.com/server/docs/how-to/debugging/debug-symbol-packages

Example of installing debug symbols for xserver-xorg-core using the -dbgsym package.

```bash
sudo apt-get install xserver-xorg-core-dbgsym
```

--------------------------------

### multipass launch --name tutorial

Source: https://ubuntu.com/server/docs/tutorial/welcome-to-the-terminal

Command to create a Multipass VM named 'tutorial' and its output. The output 'Launched: tutorial' confirms the VM was created successfully.

```text
user@computer:~$ multipass launch --name tutorial
```

```text
Launched: tutorial
```

--------------------------------

### Install nfs-kernel-server

Source: https://ubuntu.com/server/docs/how-to/networking/install-nfs

Install the NFS server package. The presence of /etc/krb5.keytab automatically starts the Kerberos-related NFS services.

```bash
sudo apt install nfs-kernel-server
```

--------------------------------

### Install cyrus-clients for smtptest

Source: https://ubuntu.com/server/docs/how-to/mail-services/install-exim4

Install the cyrus-clients package to get the smtptest tool. The --no-install-recommends option avoids installing unnecessary components of the Cyrus email system. It is recommended to install on a separate machine from Exim4.

```bash
sudo apt install cyrus-clients --no-install-recommends
```

--------------------------------

### Start OpenVPN server with systemctl

Source: https://ubuntu.com/server/docs/how-to/security/install-openvpn

Starts the OpenVPN server using the configuration file /etc/openvpn/myserver.conf.

```bash
sudo systemctl start openvpn@myserver
```

--------------------------------

### Example /etc/postfix/main.cf after configuration

Source: https://ubuntu.com/server/docs/how-to/mail-services/install-postfix

Example /etc/postfix/main.cf after running the SMTP-AUTH and TLS configuration commands. Shows the expected configuration with SMTP-AUTH enabled and TLS settings.

```text
# See /usr/share/postfix/main.cf.dist for a commented, more complete
# version
    
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
    
# appending .domain is the MUA's job.
append_dot_mydomain = no
    
# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
    
myhostname = server1.example.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = server1.example.com, localhost.example.com, localhost
relayhost =
mynetworks = 127.0.0.0/8
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
smtpd_sasl_local_domain =
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions =
permit_sasl_authenticated,permit_mynetworks,reject _unauth_destination
smtpd_tls_auth_only = no
smtp_tls_security_level = may
smtpd_tls_security_level = may
smtp_tls_note_starttls_offer = yes
smtpd_tls_key_file = /etc/ssl/private/smtpd.key
smtpd_tls_cert_file = /etc/ssl/certs/smtpd.crt
smtpd_tls_CAfile = /etc/ssl/certs/cacert.pem
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom
```

--------------------------------

### Install certificate tools packages

Source: https://ubuntu.com/server/docs/how-to/openldap/ldap-and-tls

Installs the gnutls-bin and ssl-cert packages required for generating certificates and keys in this TLS setup.

```bash
sudo apt install gnutls-bin ssl-cert
```

--------------------------------

### Copy sample client.conf to /etc/openvpn/

Source: https://ubuntu.com/server/docs/how-to/security/install-openvpn

Copy the sample client configuration file from the package documentation to the OpenVPN configuration directory.

```bash
sudo cp /usr/share/doc/openvpn/examples/sample-config-files/client.conf /etc/openvpn/
```

--------------------------------

### Install Prometheus and Alertmanager snaps

Source: https://ubuntu.com/server/docs/how-to/observability/set-up-your-lma-stack

Installs Prometheus and the Prometheus Alertmanager plugin via snap. The snap automatically configures and starts the services.

```bash
monitor:~# snap install prometheus
monitor:~# snap install prometheus-alertmanager
```

--------------------------------

### Temporary installer password output

Source: https://ubuntu.com/server/docs/how-to/installation/non-interactive-ibm-z-vm-autoinstall-s390x

Example output during the IPL boot process showing the temporary installation password generated by cloud-init. This password is needed to connect to the installer via SSH in the next step.

```default
...
|37.487141| cloud-init¬1873|: Set the following 'random' passwords
|37.487176| cloud-init¬1873|: installer: **i7UFdP8fhiVVMme3qqH8**
...
```

--------------------------------

### Mount the ISO and list boot files

Source: https://ubuntu.com/server/docs/how-to/installation/interactive-live-server-installation-on-ibm-z-lpar-s390x

Commands to loop-back mount the downloaded ISO and list the four required boot files (initrd.ubuntu, kernel.ubuntu, parmfile.ubuntu, ubuntu.exec).

```bash
mkdir iso
sudo mount -o loop ubuntu-20.04.5-live-server-s390x.iso iso
ls -1 ./iso/boot/{ubuntu.exec,parmfile.*,kernel.u*,initrd.u*}
```

--------------------------------

### Build and serve documentation with make run

Source: https://ubuntu.com/server/docs/contributing/local-development

Builds and serves the documentation at http://127.0.0.1:8000/ with live reload on file changes.

```bash
make run
```

--------------------------------

### Install isc-kea

Source: https://ubuntu.com/server/docs/how-to/networking/install-isc-kea

Installs the isc-kea package along with its binary packages including kea-dhcp4-server, kea-dhcp6-server, kea-ctrl-agent, and kea-dhcp-ddns-server. During installation, a debconf prompt appears with options to configure the kea-ctrl-agent password; if no password is set, the kea-ctrl-agent will not start.

```bash
sudo apt install kea
```

--------------------------------

### Create a virtual machine with virt-install

Source: https://ubuntu.com/server/docs/how-to/virtualisation/virtual-machine-manager

Example command to create a virtual machine named web_devel with specified RAM, disk, CD-ROM, network, graphics, and CPU options.

```bash
virt-install \
    --name web_devel \
    --ram 8192 \
    --disk path=/home/doug/vm/web_devel.img,bus=virtio,size=50 \
    --cdrom focal-desktop-amd64.iso \
    --network network=default,model=virtio \
    --graphics vnc,listen=0.0.0.0 \
    --noautoconsole \
    --hvm \
    --vcpus=4
```

--------------------------------

### Install rootless Docker daemon

Source: https://ubuntu.com/server/docs/how-to/containers/docker-for-system-admins

Run the rootless Docker setup script as a non-root user to install the rootless daemon. The script shows help if any prerequisites are not met.

```bash
/usr/share/docker.io/contrib/dockerd-rootless-setuptool.sh install
```

--------------------------------

### APT sources.list.d ubuntu.sources example

Source: https://ubuntu.com/server/docs/how-to/software/package-management

Example content of /etc/apt/sources.list.d/ubuntu.sources showing the default enabled repositories. To disable universe and multiverse, remove those entries from the Components line.

```default
Types: deb
URIs: http://archive.ubuntu.com/ubuntu
Suites: DISTRO-SHORT-CODENAME DISTRO-SHORT-CODENAME-updates DISTRO-SHORT-CODENAME-backports
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
```

--------------------------------

### Output of automatic commit after apt install postfix

Source: https://ubuntu.com/server/docs/how-to/backups/install-etckeeper

Example output from the automatic commit made by etckeeper after installing postfix, showing the commit hash, author, and list of created files.

```text
[master 5a16a0d] committing changes in /etc made by "apt install postfix"
 Author: Your Name <xyz@example.com>
 36 files changed, 2987 insertions(+), 4 deletions(-)
 create mode 100755 init.d/postfix
 create mode 100644 insserv.conf.d/postfix
 create mode 100755 network/if-down.d/postfix
 create mode 100755 network/if-up.d/postfix
 create mode 100644 postfix/dynamicmaps.cf
 create mode 100644 postfix/main.cf
 create mode 100644 postfix/main.cf.proto
 create mode 120000 postfix/makedefs.out
 create mode 100644 postfix/master.cf
 create mode 100644 postfix/master.cf.proto
 create mode 100755 postfix/post-install
 create mode 100644 postfix/postfix-files
 create mode 100755 postfix/postfix-script
 create mode 100755 ppp/ip-down.d/postfix
 create mode 100755 ppp/ip-up.d/postfix
 create mode 120000 rc0.d/K01postfix
 create mode 120000 rc1.d/K01postfix
 create mode 120000 rc2.d/S01postfix
 create mode 120000 rc3.d/S01postfix
 create mode 120000 rc4.d/S01postfix
 create mode 120000 rc5.d/S01postfix
     create mode 120000 rc6.d/K01postfix
     create mode 100755 resolvconf/update-libc.d/postfix
     create mode 100644 rsyslog.d/postfix.conf
     create mode 120000 systemd/system/multi-user.target.wants/postfix.service
     create mode 100644 ufw/applications.d/postfix
```

--------------------------------

### VM prompt example 'ubuntu@tutorial:~ $'

Source: https://ubuntu.com/server/docs/tutorial/cli-in-depth

Example of the terminal prompt shown after entering the VM with 'multipass shell tutorial'. Indicates the username is 'ubuntu' and the hostname is 'tutorial'.

```bash
ubuntu@tutorial:~ $
```

--------------------------------

### Install SSSD LDAP and Kerberos packages

Source: https://ubuntu.com/server/docs/how-to/sssd/with-ldap-and-kerberos

Installs the required packages for SSSD with LDAP and Kerberos on the client host. You may be prompted for the default Kerberos realm; this guide uses EXAMPLE.COM.

```bash
sudo apt install sssd-ldap sssd-krb5 ldap-utils krb5-user
```

--------------------------------

### Block all packages starting with linux-

Source: https://ubuntu.com/server/docs/how-to/software/automatic-updates

Configuration for /etc/apt/apt.conf.d/50unattended-upgrades that blocks all packages whose names start with 'linux-' from being automatically upgraded. Note that blocking a package may prevent dependent updates from installing.

```text
Unattended-Upgrade::Package-Blacklist {
    "linux-";
}
```

--------------------------------

### Copy sample server configuration to /etc/openvpn/myserver.conf

Source: https://ubuntu.com/server/docs/how-to/security/install-openvpn

Copies the example server configuration file to /etc/openvpn/myserver.conf. On Ubuntu 20.04 LTS or older, the file is compressed, so copy the .gz version and decompress it.

```bash
sudo cp /usr/share/doc/openvpn/examples/sample-config-files/server.conf /etc/openvpn/myserver.conf
```

```bash
sudo cp /usr/share/doc/openvpn/examples/sample-config-files/server.conf.gz /etc/openvpn/myserver.conf.gz
sudo gzip -d /etc/openvpn/myserver.conf.gz
```

--------------------------------

### Install Hyper-V role on Windows Server: Install-WindowsFeature

Source: https://ubuntu.com/server/docs/how-to/virtualisation/ubuntu-on-hyper-v

Run this command in an elevated PowerShell session on Windows Server to install the Hyper-V server role along with management tools. The -Restart flag triggers an automatic restart after installation. See Microsoft's guide for complete steps including remote installation and role verification.

```powershell
Install-WindowsFeature -Name Hyper-V -IncludeManagementTools -Restart
```

--------------------------------

### Serve built documentation with make serve

Source: https://ubuntu.com/server/docs/contributing/local-development

Serves previously built documentation without rebuilding.

```bash
make serve
```

--------------------------------

### Check installed variant with ubuntu_virt_helper --verbose

Source: https://ubuntu.com/server/docs/how-to/virtualisation/virt-hwe

Output of the ubuntu_virt_helper script with the --verbose flag, showing the installed HWE variant and the list of packages. This example illustrates the incomplete stack after the switch.

```bash
root@enticed-cichlid:~# ubuntu_virt_helper --verbose
Installed variant: hwe


4 packages:
  - qemu-block-extra-hwe (1:10.2.1+ds-1ubuntu4, src:qemu-hwe, auto)
  - qemu-utils-hwe (1:10.2.1+ds-1ubuntu4, src:qemu-hwe, manual)
  - ubuntu-helper-virt-hwe (1:10.2.1+ds-1ubuntu4, src:qemu-hwe, manual)
  - ubuntu-virt-hwe (1:10.2.1+ds-1ubuntu4, src:qemu-hwe, auto)
```

--------------------------------

### apt upgrade output example

Source: https://ubuntu.com/server/docs/tutorial/managing-software

Example output line showing where apt upgrade fetches the upgrade from for each package, including package name, version, and source.

```text
Get:1 http://archive.ubuntu.com/ubuntu resolute-updates/main amd64 libgcrypt20 amd64 1.12.0-2ubuntu0.1 [670 kB]
```
Tokens:
Raw