Ubuntu 20.04 Upgrade

패키지 업데이트
패키지를 최신 버전으로 업데이트합니다.
$ sudo apt update && sudo apt upgrade && sudo apt dist-upgrade
업데이트 완료 후 재부팅합니다.
$ sudo reboot now
더 이상 필요하지 않은 패키지를 삭제합니다.
$ sudo apt autoremove && sudo apt clean
업데이트 매니저 설치
update-manager-core가 설치되지 않은 경우 설치합니다.
$ sudo apt install update-manager-core
lts 릴리스로 업데이트 하기 위해 update-manager의 설정을 변경합니다.
$ sudo nano /etc/update-manager/release-upgrades
아래 내용과 같이 Prompt=lts로 변경합니다.
Default behavior for the release upgrader.
[DEFAULT]
# Default prompting behavior, valid options:
#
# never - Never check for, or allow upgrading to, a new release.
# normal - Check to see if a new release is available. If more than one new
# release is found, the release upgrader will attempt to upgrade to
# the supported release that immediately succeeds the
# currently-running release.
# lts - Check to see if a new LTS release is available. The upgrader
# will attempt to upgrade to the first LTS release available after
# the currently-running one. Note that if this option is used and
# the currently-running release is not itself an LTS release the
# upgrader will assume prompt was meant to be normal.
Prompt=lts
Ctrl+X – Y – Enter 하여 저장합니다.

우분투 릴리스 업그레이드
업그레이드를 진행합니다.
$ sudo do-release-upgrade
There are services installed on your system which need to be restarted when certain libraries, such as libpam, libc, and libssl, are upgraded. Since these restarts may cause interruptions of service for the system, you will normally beprompted on each upgrade for the list of services you wish to restart. You can choose this option to avoid being prompted; instead, all necessary restarts will be done for you automatically so you can avoid being asked questions on each library upgrade.
Restart services during package upgrades without asking?
No (Default)
Running services and programs that are using NSS need to be restarted, otherwise they might not be able to do lookup or authentication any more (for services such as ssh, this can affect your ability to login). Please review the following space-separated list of init.d scripts for services to be restarted now, and correct it if needed. Note: restarting sshd/telnetd should not affect any existing connections. Services to restart for GNU libc library upgrade:
OK
A new version (/tmp/filenkZG9H) of configuration file /etc/ssh/sshd_config is available, but the version installed currently has been locally modified. What do you want to do about modified configuration file sshd_config?
Default (Keep~)
A new version (/tmp/filenkZG9H) of configuration file /etc/ssh/sshd_config is available, but the version installed currently has been locally modified. What do you want to do about modified configuration file sshd_config?
OK
Restarting services possibly affected by the upgrade:
vsftpd: stopping...starting...done.
samba-ad-dc: stopping...starting...done.
smbd: stopping...starting...done.
cron: stopping...starting...done.

Services restarted successfully.
이 화면에서 꼼짝을 안하길래 새 새션 창을 열어보니 부팅이 되네. 해서 여기에서 다시
sudo apt update
sudo apt upgrade 실행
sudo apt dist-upgrade

위 과정에서 비활성화된 서드파티 저장소를 활성화합니다.

/etc/apt/sources.list.d/ 내부에 있는 *.list 파일의 내용을 확인하여

# ....... focal main # disabled on upgrade to focal
의 주석을 해제합니다.

패키지 목록을 다시 받아옵니다.

$ sudo apt update