Category: ubuntu

Change user name in ubuntu

Posted on by Bian Xi Leave a Comment on Change user name in ubuntu

Change user name in ubuntu

To change default user name ubuntu created in Raspberry Pi image, without adding a temporary user or enable root id, can be done using background job.

Commands

Change user name and home directory

usermod -l newUsername -d /home/newUsername oldUsername

Change group name

groupmod -n <newgroup> <oldgroup>

Job

The actual execution should be triggered as background job. I used screen command as below

  1. Login as ubuntu (default id)
  2. Run sudo -i to root
  3. Run screen to launch screen session
  4. Run following command, and press Ctrl-A d detach screen session immediately, without command executed.
newname=<new_user_name>
sleep 30; ps -ef | grep ^ubuntu | awk '{print $2}' | xargs kill -9 ; usermod -l $newname -d /home/$newname ubuntu; groupmod -n $newname ubuntu; mv /home/ubuntu /home/$newname
  1. Quit from console or ssh session
  2. After 30 seconds, login to the system using newname if succeeded. Othewise, use ubuntu login again.
  3. Then sudo to root and run screen -r to check if error or quit screen session.

References

How do I change my username?

Add bluetooth device from ubuntu console

Posted on by Bian Xi Leave a Comment on Add bluetooth device from ubuntu console

Add bluetooth device from ubuntu console

I used following steps to add bluetooth keyboard.

Steps

  • Run bluetoothctl, then get following prompt
[bluetooth]#
  • Run following commands to initialize bluetooth
power on
agent on
default-agent
scan on

  • Find the bluetooth device mac address

  • Run following command to connect to it

trust XX:XX:XX:XX:XX:XX
pair XX:XX:XX:XX:XX:XX
connect XX:XX:XX:XX:XX:XX
  • Then disable scan and quit
scan off
exit

References

How to connect bluetooth headset via command line on ubuntu 12.04

Verify package using debsums

Posted on by Bian Xi Leave a Comment on Verify package using debsums

Verify package using debsums

Verify every installed package

debsums

Verify every installed package (including configuration files).

debsums -a

Verify installed packages and report errors only

debsums -s

Verify every installed package and report changed files only

debsums -c

Verify every installed package (including configuration files) and report changed files only.

debsums -ca

Verify every installed package and report changed configuration files only.

sudo debsums -ce

Verify specific package

debsums -a bash

Create mismatch list

dpkg-query -S $(sudo debsums -c 2>&1 | sed -e "s/.*file \(.*\) (.*/\1/g") | cut -d: -f1 | sort -u

To reinstall them

apt-get install --reinstall <package name>

References

How to verify installed packages

Ubuntu grub-efi-amd64-signed error after do-release-upgrade

Posted on by Bian Xi Leave a Comment on Ubuntu grub-efi-amd64-signed error after do-release-upgrade

Ubuntu grub-efi-amd64-signed error after do-release-upgrade

Following error occurred whenever run apt upgrade after perform do-release-upgrade

dpkg: error processing package grub-efi-amd64-signed (–configure):
installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 32

Solution

Reinstall all grub group packages using following commands

sudo apt-get purge grub\*
sudo apt-get install grub-efi
sudo apt-get autoremove
sudo update-grub

Remove ubuntu zfs snapshots

Posted on by Bian Xi Leave a Comment on Remove ubuntu zfs snapshots

Remove ubuntu zfs snapshots

There are so many snapshots when using zfs in ubuntu.

Issue

When tried to do release update, got following error

# do-release-update
...
...
Not enough free disk space 

The upgrade has aborted. The upgrade needs a total of 256 M free 
space on disk '/boot'. Please free at least an additional 91.4 M of 
disk space on '/boot'. You can remove old kernels using 'sudo apt 
autoremove' and you could also set COMPRESS=xz in 
/etc/initramfs-tools/initramfs.conf to reduce the size of your 
initramfs. 
...

This error messsage was occurred many times before, but those systems had very small /boot partition or many old kernels kept. If it is the first case, total repartitioning and moving root filesystem are required.

Space on /boot

Examing disk space for bpool, found that zfs reported 675MB used in bpool, but actual usage is only 242MB.

root@ubuntu:~# zpool list
NAME    SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
bpool   960M   675M   285M        -         -    30%    70%  1.00x    ONLINE  -
rpool  17.5G  7.99G  9.51G        -         -    21%    45%  1.00x    ONLINE  -
root@ubuntu:~# zfs list bpool
NAME    USED  AVAIL     REFER  MOUNTPOINT
bpool   675M   157M       96K  /boot
root@ubuntu:~# du -cshx /boot
242M    /boot
242M    total
root@ubuntu:~#

Then found many snapshots both in bpool and data pool

root@ubuntu:~# zfs list -t snapshot | head
NAME                                                               USED  AVAIL     REFER  MOUNTPOINT
bpool/BOOT/ubuntu_e8m8h0@autozsys_ywm1ok                             0B      -      238M  -
bpool/BOOT/ubuntu_e8m8h0@autozsys_ms74md                             0B      -      238M  -
bpool/BOOT/ubuntu_e8m8h0@autozsys_ugu9z7                            80K      -      242M  -
bpool/BOOT/ubuntu_e8m8h0@autozsys_r3xqau                            72K      -      242M  -
bpool/BOOT/ubuntu_e8m8h0@autozsys_nkagbh                             0B      -      242M  -
bpool/BOOT/ubuntu_e8m8h0@autozsys_xdbwsy                             0B      -      242M  -
bpool/BOOT/ubuntu_e8m8h0@autozsys_zrt7vi                            72K      -      242M  -
bpool/BOOT/ubuntu_e8m8h0@autozsys_jbmnwk                            72K      -      242M  -
bpool/BOOT/ubuntu_e8m8h0@autozsys_0e5p2e                            64K      -      242M  -
root@ubuntu:~# 
root@ubuntu:~# zfs list -t snapshot | wc
    301    1505   27701

Too many! Not sure how many snapshots ubuntu likes to create

Removing snapshots

List all snapshots for /boot

root@ubuntu:~# df /boot
Filesystem               1K-blocks   Used Available Use% Mounted on
bpool/BOOT/ubuntu_e8m8h0    408192 247808    160384  61% /boot
root@ubuntu:~# zfs list -H -o name -t snapshot bpool/BOOT/ubuntu_e8m8h0
bpool/BOOT/ubuntu_e8m8h0@autozsys_ywm1ok
bpool/BOOT/ubuntu_e8m8h0@autozsys_ms74md
bpool/BOOT/ubuntu_e8m8h0@autozsys_ugu9z7
bpool/BOOT/ubuntu_e8m8h0@autozsys_r3xqau
bpool/BOOT/ubuntu_e8m8h0@autozsys_nkagbh
bpool/BOOT/ubuntu_e8m8h0@autozsys_xdbwsy
bpool/BOOT/ubuntu_e8m8h0@autozsys_zrt7vi
bpool/BOOT/ubuntu_e8m8h0@autozsys_jbmnwk
bpool/BOOT/ubuntu_e8m8h0@autozsys_0e5p2e
bpool/BOOT/ubuntu_e8m8h0@autozsys_b17dwn
bpool/BOOT/ubuntu_e8m8h0@autozsys_uad1rb
bpool/BOOT/ubuntu_e8m8h0@autozsys_mxhvc9
bpool/BOOT/ubuntu_e8m8h0@autozsys_9athz8
bpool/BOOT/ubuntu_e8m8h0@autozsys_61umv1
bpool/BOOT/ubuntu_e8m8h0@autozsys_1q65cz
root@ubuntu:~#

Then remove them

zfs list -H -o name -t snapshot bpool/BOOT/ubuntu_e8m8h0 | xargs -n 1 zfs destroy

Now, it is ok to upgrade

root@ubuntu:~# zfs list -o space bpool
NAME   AVAIL   USED  USEDSNAP  USEDDS  USEDREFRESERV  USEDCHILD
bpool   589M   243M        0B     96K             0B       243M
root@ubuntu:~#

Docker Compose – wordpress

Posted on by Bian Xi Leave a Comment on Docker Compose – wordpress

Docker Compose - wordpress

Simple steps to start using docker compose to create wordpress dockers.

Installation

Install docker-compose package

Run following command on ubuntu and armbian servers.

apt install docker-compose

Create dockers

Create folder as project name wp

The project name will be used as a part of docker container name.

mkdir -p /app/wp

Create docker compose file

Using vi to create file docker-compose.yml in directory /app/wp

version: "3.3"

services:
  db:
    image: mariadb:latest
    volumes:
      - db_data:/var/lib/mysql
    ports:
      - "3306:3306"
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: somewordpress
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: wordpress

  wordpress:
    depends_on:
      - db
    image: wordpress:latest
    volumes:
      - wordpress_data:/var/www/html
    ports:
      - "80:80"
    restart: always
    environment:
      WORDPRESS_DB_HOST: db:3306
      WORDPRESS_DB_USER: wordpress
      WORDPRESS_DB_PASSWORD: wordpress
      WORDPRESS_DB_NAME: wordpress
volumes:
  db_data: {}
  wordpress_data: {}

Run docker compose command

docker-compose up -d

Destroy dockers

Run docker compose command

docker-compose down

Destroy dockers and their volumes

docker-compose down --volumes