Category: Linux

linux software installation
October 2, 2021

Install Thin web server

Thin is a Ruby web server that can handle high levels of concurrency.

Install it with

gem install thin

root@server70 [/home/redmine]# gem install thin
Building native extensions.  This could take a while...
Building native extensions.  This could take a while...
Successfully installed eventmachine-0.12.10
Successfully installed daemons-1.1.2
Successfully installed thin-1.2.11
3 gems installed
Installing ri documentation for eventmachine-0.12.10...
Installing ri documentation for daemons-1.1.2...
Installing ri documentation for thin-1.2.11...
Installing RDoc documentation for eventmachine-0.12.10...
Could not find main page README
Could not find main page README
Could not find main page README
Could not find main page README
Installing RDoc documentation for daemons-1.1.2...
Installing RDoc documentation for thin-1.2.11...
root@server70 [/home/redmine]#

Installing thin on Ubuntu

You can install thin web server on Ubuntu/Debian using

apt install thin

October 2, 2021

How to host static site using pm2
PM2 is a process manager for node.js applications. You can use PM2 to host static websites.

To host a static website, create a folder, and put your files inside.
```
mkdir /home/website
```
Let’s create a static file, say index.html
```
echo "Welcome" > /home/website/index.html
```
Now you can make the site live using the following pm2 command
```
pm2 serve /home/website 8082
```
Now the static site will be available at
```
http://localhost:8082
```
If you have a Single Page Application (SPA) like Angular, React, you can use the option –spa with pm2 command so all non-existent pages get routed to index.html internally.
```
pm2 serve --spa
```
October 1, 2021
dmidecode
dmidecode is a tool for dumping a computer’s DMI (SMBIOS ) table contents in a human-readable format. This table contains a description of the system’s hardware components, as well as other useful pieces of information such as serial numbers and BIOS revision. Thanks to this table, you can retrieve this information without having to probe for the actual hardware. While this is a good point in terms of report speed and safeness, this also makes the presented information possibly unreliable.

The DMI table doesn’t only describe what the system is currently made of, it also can report the possible evolutions (such as the fastest supported CPU or the maximal amount of memory supported).

SMBIOS stands for System Management BIOS, while DMI stands for Desktop Management Interface. Both standards are tightly related and developed by the DMTF (Desktop Management Task Force).

To see system details, run
```
dmidecode
```
How to find RAM details in Linux
September 14, 2021
How to find RAM details in Linux
To find RAM memory details (model number/manufacturer) in Linux, you can use the command
```
dmidecode --type 17
```
To show only model numbers, run
```
dmidecode --type 17 | grep "Part Number"
```
Once you find the Part Number, you can search in google for the part number to see more details about the RAM.

On Ubuntu/Debian, you can install dmidecode with the command
```
apt install -y dmidecode
```
On RHEL, CentOS, OracleLinux, you can use the command
```
yum install dmidecode
```
On newer RHEL systems, you can use dnf instead of yum.
September 13, 2021

How to Install Elasticsearch in Docker

To Install Elasticsearch with Docker, first, you need to install docker on your server with command

wget -qO- https://get.docker.com/ | sh

Docker images for Elasticsearch are available from

https://hub.docker.com/_/elasticsearch

You can see all available versions at

https://hub.docker.com/_/elasticsearch?tab=tags&page=1&ordering=last_updated

To create an elasticsearch container, run

docker run -p 9200:9200 -p 9300:9300 -e "discovery.type=single-node" docker.elastic.co/elasticsearch/elasticsearch:7.5.2

To run it in the background

docker run --name sok-elasticsearch --restart=unless-stopped \
 -d -p 9200:9200 -p 9300:9300 \
 -e "xpack.security.enabled=false" \
 -e "discovery.type=single-node" docker.elastic.co/elasticsearch/elasticsearch:7.5.2

To verify if ElasticSearch works, run

boby@sok-01:~$ curl localhost:9200
{
  "name" : "730d385743b3",
  "cluster_name" : "docker-cluster",
  "cluster_uuid" : "V9XDIPXZQt-Tfgcy8hoIDg",
  "version" : {
    "number" : "7.5.2",
    "build_flavor" : "default",
    "build_type" : "docker",
    "build_hash" : "8bec50e1e0ad29dad5653712cf3bb580cd1afcdf",
    "build_date" : "2020-01-15T12:11:52.313576Z",
    "build_snapshot" : false,
    "lucene_version" : "8.3.0",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "You Know, for Search"
}
boby@sok-01:~$

Back to Elasticsearch

September 7, 2021

How to find CPU of a Linux Server

To find CPU used on a Linux system, run command

cat /proc/cpuinfo

Example

boby@sok-01:~$ cat /proc/cpuinfo | grep -i "model name"
model name	: AMD Ryzen 3 2200G with Radeon Vega Graphics
model name	: AMD Ryzen 3 2200G with Radeon Vega Graphics
model name	: AMD Ryzen 3 2200G with Radeon Vega Graphics
model name	: AMD Ryzen 3 2200G with Radeon Vega Graphics
boby@sok-01:~$

September 4, 2021

How to Delete Website (Virtual Server) in Virtualmin
In the Virtualmin Hosting control panel, websites are called Virtual Server. To delete a website, click on the Virtualmin tab.

From the dropdown menu, select the website you need to delete.

On the left menu, click on “Disable and Delete’. Then click on “Delete Virtual Server” Link.
```
Virtualmin > Domain > Disable and Delete > Delete Virtial Server
```
It will ask for confirmation. Click on the red “Yes, Delete it” button to delete the website.

See Virtualmin
September 4, 2021
How to display /proc/*/environ file in separate lines?
environ is a file located in /proc/PID/environ, it shows environment variables for a process.

If you run “cat environ”, you will get a long string.

To make it readable, you can use sed command.
```
cat environ | sed -z 's/$/\n/'
```
Example
September 3, 2021

Watermark video using ffmpeg

To watermark video using FFmpeg, run

ffmpeg -i SOURCE.mp4 -vf "drawtext=text='WATERMARK_TEXT':x=10:y=H-th-10:fontsize=32:fontcolor=white:shadowcolor=black:shadowx=2:shadowy=2" OUT.mp4

In the above command replace

SOURCE.mp4 = file name of the video you need to watermark.
OUT.mp4 = file name for the watermarked video.
WATERMARK_TEXT =  Text you need to watermark on the video.

See ffmpeg

August 31, 2021

Lego – LetsEncrypt client
Lego is a Let’s Encrypt client and ACME library written in Go.

https://go-acme.github.io/lego

Install Lego

To install go to the release page, download the latest version.
```
wget https://raw.githubusercontent.com/serverok/server-setup/master/install/lego.sh
bash ./lego.sh
```
Create SSL certificate

To create an SSL certificate standalone (built-in webserver), run
```
lego --accept-tos --http --email="EMAIL-ADDRESS" --key-type rsa2048 --domains="DOMAIN_NAME" --domains="www.DOMAIN_NAME" --path="/etc/lego" run
```
If you need to verify using port 443, use “–tls” instead of “–http”

Verify SSL using webroot (existing webserver)
```
lego --accept-tos --http --http.webroot="/var/www/html/" --email="EMAIL-ADDRESS" --key-type rsa2048 --domains="DOMAIN_NAME" --domains="www.DOMAIN_NAME" --path="/etc/lego" run
```
Issue Wildcard SSL using manual DNS verification
```
lego --email "EMAIL-ADDRESS" --key-type rsa2048 --domains="DOMAIN_NAME" --domains="*.DOMAIN_NAME" --dns "manual" --path="/etc/lego" run
```
Renew SSL certificate

To renew the SSL certificate, use the same command as SSL creation with “run” replaced with
```
renew --days 30
```
–days 30 means SSL will be renewed if the expiry date is with 30 days. If you need to force renew SSL, use –days 90.

Now run
```
lego --http --http.webroot="/var/www/html/" --email="EMAIL-ADDRESS" --key-type rsa2048 --domains="DOMAIN_NAME" --domains="www.DOMAIN_NAME" --path="/etc/lego" renew --days 30
```
You need to restart the webserver after running this command.

Renew Hook

If you need to execute a script after SSL renewal, you can add
```
--renew-hook="./myscript.sh"
```
Example
```
lego --http --http.webroot="/var/www/html/" --email="EMAIL-ADDRESS" --key-type rsa2048 --domains="DOMAIN_NAME" --domains="www.DOMAIN_NAME" --path="/etc/lego" renew --days 30 --renew-hook="./myscript.sh"
```
If you are using the standalone method, you need to stop the webserver before running the lego command.

SSL certificates will be in the directory
```
/etc/lego/certificates/
```
Make it readable by the web server with the command
```
chmod -R 755 /etc/lego/
```
See letsencrypt
August 29, 2021
Debian 11.0 Bullseye released

Debian 11.0 Bullseye released on August 14th, 2021 is the next major Debian GNU/Linux distribution release. Debian 10 buster is designated as oldstable.

https://www.debian.org/releases/bullseye/

Debian 12 “Bookworm” is the new testing distribution with is expected to be released in 2023.

You can download the latest version of Debian 11.0 ISO from

https://www.debian.org/download

What is new in Debian 11.0

Debian 11.0 is powered by Linux 5.10 LTS kernel. It supports exFAT file system. Control groups v2 support. Improved support for alternative init systems.

The new release of Debian 11.0 comes with a lot more software packages. It includes 11294 new packages. Most software on the distribution has been updated.

You can find the list of software packages and versions at

https://www.debian.org/releases/stable/amd64/release-notes/ch-whats-new.en.html#major-packages

Upgrade Debian 10 to Debian 11.0

You can find instructions for upgrading Debian 10 to Debian 11.0 at

https://www.debian.org/releases/stable/amd64/release-notes/ch-upgrading.en.html

See Debian

August 26, 2021

Category: Linux

Installing thin on Ubuntu

Install Lego

Create SSL certificate

Renew SSL certificate

Renew Hook

What is new in Debian 11.0

Upgrade Debian 10 to Debian 11.0