Category: Ubuntu

How to convert images to webp format in Ubuntu
Webp is a new image format for the web. It can be used on websites for the fast and efficient loading of images. Webp is an open-source image format created by Google and quickly getting adopted by web developers.

If you use Ubuntu or Debain, you can install webp from the official repository with the command
```
sudo apt-get install webp
```
To convert an image to webp format, open the terminal and run
```
cwebp FILE.png -o FILE.webp
```
If you want to specify the quality of the converted webp image, you can use -q option.
```
cwebp -q 60 FILE.png -o FILE.webp
```
Image viewer comes with Ubuntu won’t display webp images. To view webp images, you can open them in the GIMP image editor or drag and drop them in a web browser. Another way is to use the command-line tool that comes with webp package.
```
vwebp FILE.webp
```
April 7, 2022

Install CSF firewall on Ubuntu Server

First, install libwww-perl package needed for CSF firewall

apt -y install libwww-perl

Install CSF with

cd /usr/local/src
wget https://download.configserver.com/csf.tgz
tar -xzf csf.tgz
cd csf
sh install.sh

Change following settings in csf.conf file

/bin/sed -i "s/RESTRICT_SYSLOG\s*=.*$/RESTRICT_SYSLOG = \"3\"/g" /etc/csf/csf.conf
/bin/sed -i "s/SYSLOG_CHECK\s*=.*$/SYSLOG_CHECK = \"3600\"/g" /etc/csf/csf.conf
/bin/sed -i "s/TESTING = \"1\"/TESTING = \"0\"/g" /etc/csf/csf.conf

If you need GUI enabled, edit file

vi /etc/csf/csf.conf

Modify following settings

UI = "1"
UI_PORT = "8282"
UI_USER = "username"
UI_PASS = "password"
UI_ALLOW = "0"

March 26, 2022

dpkg dependency problems not removing

When removing a package, I got the following error message

root@82-165-118-245:/~# dpkg --remove psa-phpmyadmin
dpkg: dependency problems prevent removal of psa-phpmyadmin:
 plesk-core depends on psa-phpmyadmin (>= 5.1.1); however:
  Package psa-phpmyadmin is to be removed.

dpkg: error processing package psa-phpmyadmin (--remove):
 dependency problems - not removing
Errors were encountered while processing:
 psa-phpmyadmin
root@82-165-118-245:/~#

It is fixed by specifying –ignore-depends=plesk-core in apt command.

Example

root@82-165-118-245:/~# dpkg --remove --ignore-depends=plesk-core psa-phpmyadmin
(Reading database ... 168316 files and directories currently installed.)
Removing psa-phpmyadmin (5.1.1-v.ubuntu.18.04+p18.0.38.0+t210825.1032) ...
root@82-165-118-245:/~#

February 12, 2022

dpkg package pre-removal script returned error

On a Plesk server, MySQL somehow went missing. When I tried to remove a package, I get error

root@82-165-118-245:~# dpkg --remove plesk-config-troubleshooter
(Reading database ... 168528 files and directories currently installed.)
Removing plesk-config-troubleshooter (18.0-v.ubuntu.18.04+p18.0.39.2+t211117.1817) ...
dpkg action: 

ERROR while trying to detect MySQL service name

Check the error reason (see log file: /var/log/plesk/install/plesk_18.0.39_installation.log), fix and try again
dpkg action: 

ERROR while trying to detect MySQL service name


Package script failed

***** installing problem report *****
ERROR while trying to detect MySQL service name
Package script failed
dpkg: error processing package plesk-config-troubleshooter (--remove):
 installed plesk-config-troubleshooter package pre-removal script subprocess returned error exit status 1
Errors were encountered while processing:
 plesk-config-troubleshooter
root@82-165-118-245:~#

To fix this, I removed the prerm and postrm scripts. These scripts execute before and after a package is removed. It is not recommended to remove it, but if these scripts prevent you from uninstalling a package, you can remove them as the last option.

mv /var/lib/dpkg/info/plesk-config-troubleshooter.prerm ~/
mv /var/lib/dpkg/info/plesk-config-troubleshooter.postrm ~/

Or you can just edit the file, put

exit 0

somewhere before the error happens.

February 12, 2022

Convert image to WebP format in Ubuntu
WebP is an image format for web by Google. The size of webp images are much smaller compared with other image formats, so better to use webp images on websites for faster site load speed.

To install webp on Ubuntu/Debian, run
```
sudo apt install webp
```
To convert an image to webp format, run
```
cwebp image.png -o image.webp
```
With the above command, image.png file gets converted to image.webp

You can specify quality with -q option
```
-q  ............. quality factor (0:small..100:big), default=75
```
To view a webp image, run
```
vwebp image.webp
```
December 13, 2021
bash: /usr/bin/man: No such file or directory
On Ubuntu, I get the following error
```
root@vps1:~# man
bash: /usr/bin/man: No such file or directory
root@vps1:~#
```
This is fixed by installing man with apt-get
```
apt-get install man
```
December 11, 2021
How to disable GUI in Ubuntu
If you have installed Ubuntu with GUI and don’t want GUI, you can disable GUI from starting on boot with command
```
systemctl set-default multi-user
```
If you need to GUI auto-start on boot, run
```
systemctl set-default graphical.target
```
December 9, 2021
Configure Failover IP in Ubuntu 20.04 OVH VPS
To configure IP on OVH VPS, you need to manually configure networking as OVH gateway is outside the failover IP subnet. For most hosting providers getaway will be in the same subnet as the IP address. To configure IP using netplan, see instruction here.

First, install ifupdown package
```
apt install -y ifupdown
```
Now edit file
```
vi /etc/network/interfaces
```
Add
```
auto NETWORK_INTERFACE_HERE
iface NETWORK_INTERFACE_HERE inet static
    address FO_IP_ADDR
    netmask 255.255.255.255
    broadcast FO_IP_ADDR
    dns-nameservers 8.8.8.8 8.8.4.4
    post-up ip route add GATEWAY_ADDR dev NETWORK_INTERFACE_HERE
    post-up ip route add default via GATEWAY_ADDR dev NETWORK_INTERFACE_HERE
    pre-down ip route del GATEWAY_ADDR dev NETWORK_INTERFACE_HERE
    pre-down ip route del default via GATEWAY_ADDR dev NETWORK_INTERFACE_HERE
```
In the above text, replace

NETWORK_INTERFACE_HERE = with your actual network interface name, for example, eth0, ens18, etc.
FO_IP_ADDR = Your VPS IP address, OVH calls this Failover IP address. It is just any secondary IP address you purchase.
GATEWAY_ADDR = Gateway IP address. This is the same as the Main IP of the server with the last octal replaced by 254

Example

Configuration is the same as Ubuntu 18.04, the only difference is post-up and pre-down tines, where Ubuntu 18.04 used older route command, in Ubuntu 20.04, we use “ip route” command instead.
November 26, 2021
Module php-imagick in this instance has no SVG support
On Ubuntu server running Nextcloud, I got the following warning in Nextcloud
```
Module php-imagick in this instance has no SVG support. For better compatibility it is recommended to install it.
```
To fix this warning, install libmagickcore-6.q16-6-extra package with the command
```
apt-get install libmagickcore-6.q16-6-extra
```
See Nextcloud
October 28, 2021
How to install zabbix agent on Ubuntu
To install the Zabbix agent on Ubuntu, run the command
```
apt install zabbix-agent
```
To autostart, Zabbix agent on boot, enable it with
```
systemctl enable zabbix-agent
```
To manage Zabbix, use commands
```
systemctl stop zabbix-agent
systemctl start zabbix-agent
systemctl restart zabbix-agent
```
To see Zabbix listening port
```
netstat -lntp | grep zabbix
```
Edit file
```
vi /etc/zabbix/zabbix_agentd.conf 
```
Find
```
Server=127.0.0.1
```
Replace with
```
Server=127.0.0.1,IP_OF_ZABBIX_SERVER_HERE
```
Restart zabbix agent
```
systemctl restart zabbix-agent
```
After the Zabbix agent is installed, you need to add the sevrer in your Zabbix installation.
October 16, 2021
How to install development tools on Debian/Ubuntu
Development tools are programs used to build software from its source code. These include compilers, make, and other generally used libraries.

To install development tools on Ubuntu/Debian, run
```
apt install -y build-essential
apt install -y autoconf automake gdb libffi-dev zlib1g-dev libssl-dev git wget
```
See Ubuntu, Debian
July 28, 2021
bash: lspci: command not found
On Ubuntu server, when I run lspci command, I get the error
```
root@first-vm:~# lspci
-bash: lspci: command not found
root@first-vm:~# 
```
To fix this error, install the package pciutils
```
apt install -y pciutils
```
See lspci
July 17, 2021