Ubuntu Commands
Misc. Ubuntu commands.
Remove Pre-installed
If you don’t know what they are …
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| apt purge cloud-* snapd whoopsie* unattended-upgrades ubuntu-advantage-tools
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If not using LVM, LXC/LXD
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| apt purge lvm2 lxd lxcfs
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If completely rely on journald.
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| apt purge rsyslog libestr0 libfastjson4
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Get Version
Change Timezone
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| dpkg-reconfigure tzdata
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systemd-resolver
Ubuntu/Systemd use systemd-resolver for dns lookup and /etc/resolve.conf no longer show the actual upstream dns. Use following to check and change.
Show DNS Settings
Change DNS
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| resolvectl dns <interface> <dns1> <dns2> ...
resolvectl dns enp0s2 8.8.8.8 8.8.4.4 1.1.1.1
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Change Search Domain
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| resolvectl domain <interface> <domain>
resolvectl domain enp0s2 johnsiu.com
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Disable CPU mitigations
Do this at your own risk.
/etc/default/grub
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| GRUB_CMDLINE_LINUX_DEFAULT="noibrs noibpb nopti nospectre_v2 nospectre_v1 l1tf=off nospec_store_bypass_disable no_stf_barrier mds=off mitigations=off"
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Update GRUB
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| update-grub
grub-install <boot disk>
grub-install /dev/sda
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Update Initramfs
This is needed if module used during boot is changed.
Ubuntu Release Upgrade
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| apt install update-manager-core
do-release-upgrade -d
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Netplan
Apply netplan changes. Will not apply if there is syntax error in configuration files:
Try, will apply and auto revert:
Purge Uninstalled Packages
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| apt-get purge $(dpkg -l | grep '^rc' | awk '{print $2}')
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APT Cache
On apt cache server:
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| apt install apt-cacher-ng
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On other server:
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| echo 'Acquire::http::Proxy "http://<cache-server>:3142";' > /etc/apt/apt.conf.d/00proxy
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John Siu
Update: 2020-08-12