Linux on myblog

Bash

Thu, 18 Sep 2025 21:29:01 +0800

Using Variables in Shell Scripts

Welcome back to the world of shell scripting. In the previous lesson, you crafted your very first shell script that printed “Hello, World!” to the screen. Today, we will take the next step by exploring how to use variables in shell scripts. This lesson will introduce you to variable declaration, reassignment, and some basic arithmetic operations.

Using variables can make your scripts more dynamic and flexible, allowing you to store information, reuse values, and perform calculations. Let’s get started!

OpenWrt

Fri, 01 Nov 2024 21:29:01 +0800

BRI-R3 Mini

https://wiki.banana-pi.org/Getting_Started_with_BPI-R3_MINI

https://downloads.openwrt.org/snapshots/targets/mediatek/filogic/

https://firmware-selector.openwrt.org/?version=SNAPSHOT&target=mediatek%2Ffilogic&id=bananapi_bpi-r3-mini

https://openwrt.org/toh/sinovoip/bananapi_bpi_r3_mini?s[]=bananapi&s[]=bpi&s[]=r3&s[]=mini

Unbrick Nand from Emmc U-Boot

usb start

usb storage

Device 0: Vendor: SanDisk Rev: 1.00 Prod: Cruzer Blade
            Type: Removable Hard Disk
            Capacity: 14664.0 MB = 14.3 GB (30031872 x 512)

usb tree

USB device tree:
  1  Hub (5 Gb/s, 0mA)
  |  U-Boot XHCI Host Controller
  |
  +-2  Mass Storage (480 Mb/s, 200mA)
       SanDisk Cruzer Blade 03025908011622061257

ls usb 0:1

fatload usb 0:1 $loadaddr openwrt-mediatek-filogic-bananapi_bpi-r3-mini-snand-factory.bin

fatload usb 0:1 $loadaddr mtk-bpi-r3mini-NAND-20231115-single-image.bin

nand erase 0x0 0x8000000

nand write $loadaddr 0 0x8000000

switch to nand

NFS

Mon, 01 Apr 2024 21:29:01 +0800

Install Server NFS

update

sudo apt update

install nfs server

sudo apt install nfs-kernal-server

view if nfs ok

rpcinfo -p | grep nfs

other ways view if ok

cat /proc/filesystems | grep nfs

enable nfs-server start after restart

sudo systemctl enable nfs-server

create folder

sudo mkdir /mnt/nfs

chown nobody:nogroup /mnt/nfs

admin privilege on folder

sudo chmod -R 777 /mnt/nfs

edit exports file

sudo nano /etc/exports

The /etc/exports Options

General Options	Description
secure	Requires request originate on secure ports, those less than 1024. This is on by default.
insecure	Turns off the secure option.
ro	Allows only read-only access. This is the default.
rw	Allows read/write access.
sync	Performs all writes when requested. This is the default.
async	Performs all writes when the server is ready.
no_wdelay	Performs writes immediately, not checking to see if they are related.
wdelay	Checks to see if writes are related, and, if so, waits to perform them together. Can degrade performance. This is the default.
hide	Automatically hides an exported directory that is the subdirectory of another exported directory. The subdirectory has to be explicitly mounted to be accessed. Mounting the parent directory does not allow access. This is the default.
no_hide	Does not hide an exported directory that is the subdirectory of another exported directory (opposite of hide). Only works for single hosts and can be unreliable.
subtree_check	Checks parent directories in a file system to validate an exported subdirectory. This is the default.
no_subtree_check	Does not check parent directories in a file system to validate an exported subdirectory.
insecure_locks	Does not require authentication of locking requests. Used for older NFS versions.

User ID Mapping	Description
all_squash	Maps all UIDs and GIDs to the anonymous user. Useful for NFS-exported public FTP directories, news spool directories, and so forth.
no_all_squash	The opposite option to all_squash. This is the default setting.
root_squash	Maps requests from remote root user to the anonymous UID/GID. This is the default.
no_root_squash	Turns off root squashing. Allows the root user to access as the remote root.
anonuid
anongid	Sets explicitly the UID and GID of the anonymous account used for all_squash and root_squash options. The defaults are nobody and nogroup.

exemple:

Ansible

Sun, 03 Sep 2023 21:29:01 +0800

Host

[frontend_servers]
reactjs_one ansible_host=192.168.1.200 ansible_user=ubuntu ansible_ssh_private_key=~/.ssh/id_rsa

ansible -i hosts frontend_servers -m ping

ansible.cfg

[defaults]
host_key_checking = False
inventory         = ./hosts

reactjs.yaml

---
- hosts: frontend_servers
  
  vars:
    project_path: /var/www
    repository: gitlab.com/danpoznanski/example.git

  tasks: 

    - name: "Yarn | GPG"
      apt_key:
        url: https://dl.yarnpkg.com/debian/pubkey.gpg
        state: present
    
    - name: "Yarn | Ensure Debian sources list file exists"
      file: 
        path: /etc/apt/sources.list.d/yarn.list
        owner: root
        mode: 0644
        state: touch
    
    - name: "Yarn | Update APT cache"
      apt:
        update_cache: yes
    
    - name: Install the packages YARN, NPM, NodeJS, Nginx
      apt:
        pkg: ['yarn','npm','nodejs','nginx']
    
    - name: Delete the html file
      file:
        path: "{{project_path}}/html"
        state: absent
    
    - name: Set some variable
      set_fact:
      release_path: "{{ project_path }}/releases/{{ lookup('pipe','date +%Y%m%d%H%M%S',) }}"
      current_path: "{{ project_path }}/html"
    
    
    - name: Create project path
      file: 
        dest={{ project_path }}
        mode=0755
        recurse=yes
        state=directory

    - name: Retrieve current release folder
      command: readlink -f html
      register: current_release_path
      ignore_errors: yes
      args:
        chdir: "{{ project_path }}"
    
    - name: Create Release folder
      file:
        dest={{ release_path }}
        mode=0755
        recurse=yes
        state=directory

    - name: Clone the repository
      git:
        repo: "{{ repository }}"
        dest: "{{ release_path }}"
    
    - name: YARN install dependencies
      command: yarn install
      args:
        chdir: "{{ release_path }}"
    
    - name: Yarn build
      command: yaen build
      args:
        chdir: "{{ release_path }}"
    
    - name: Update symlink
      file:
        scr={{ release_path }}/build
        dest={{ current_path }}
        state=link

run playbook -b or --become its sudo

Ngrok

Sun, 03 Sep 2023 21:29:01 +0800

Ngrok on Ubuntu

after download ngrok Unzip

create folders and file

root/.config/ngrok/ngrok.yml

# in ngrok.yml
authtoken: 2UoPmLJDDOzSLlTA3obRZuswHTN_ZbmHcjZYLDdsPShY5KYP
version: 2
region: us

for config ./ngrok config edit

to run ./ngrok http 8080

SonarQube

Sun, 03 Sep 2023 21:29:01 +0800

Install SonarQube on Ubuntu

Modify Kernel System Limits

SonarQube uses Elasticsearch to store its indices in an MMap FS directory. It requires some changes to the system defaults.

Edit the sysctl configuration file

sudo nano /etc/sysctl.conf

Add the following lines:

vm.max_map_count=262144
fs.file-max=65536
ulimit -n 65536
ulimit -u 4096

Save and exit the file

Reboot the system to apply the changes

sudo reboot

install Java

See vesion

java-version

install java 17 need for sonarqube 10 for sonarqube 9 need java 11

Loki

Tue, 01 Aug 2023 21:29:01 +0800

The architecture of Loki

A brief overview of components in Loki architecture:

Promtail - It is the log collection agent that runs on each node of a Kubernetes cluster.
Distributor - The first component to receive logs from promtail.
Ingestor - It builds compressed chunks of log data and flushes them out as chunks.
Querior - It handles the read path, scanning the index to figure out which chunks match

Prometheus

Tue, 01 Aug 2023 21:29:01 +0800

Prometheus

Prometheus - database of time series
Exporter - instrument for get metric
Alertmanager - notification and everything is connected with it

Basic startup parameters

We will start looking at the configuration file in the next task, but now let’s look at the main Prometheus startup keys:

--config.file="prometheus.yml" - which configuration file to use;

--web.listen-address="0.0.0.0:9090" - the address that the embedded web server will listen to;

--web.enable-admin-api - enable or disable administrative API via web-interface;

Puppet

Tue, 01 Aug 2023 21:29:01 +0800

CRM Configuration Management System

Diagram of Work Puppet Push/Pull

Vagrant

Wed, 03 May 2023 21:29:01 +0800

Example

vagrantfile

vagrant.configure("2") do |config|
  
  config.vm.provider :virtualbox do |v|
    v.memory = 2048
  end

  config.vm.define "reactjsserver" do |db|
    db.vm.box = "ubuntu/focal64"
    db.vm.hostname = "reactjsserver"
    db.vm.network :private_network, ip: "10.10.10.10"
    db.vm.provision "ansible" do |ansible"
        ansible.playbook = "OneServer/reactjs.yaml"
        ansible.become = true
    end 
  end
end

run vagrant

vargant up

connect to vagrant virtualmachine

vagrant ssh

ss -tlpn see all ports

see all boxes

vagrant box list

delete virtual machine

vagrant destroy

Search Boxes

https://app.vagrantup.com/boxes/search

Terraform

Mon, 03 Apr 2023 21:29:01 +0800

structura of terraform:

main.tf

outputs.tf

terraform.tfstate

terraform.tfstate.backup

variable.tf

used for create new project terraform init command in Terraform initializes a new or existing Terraform configuration, setting up the environment, downloading necessary plugins, modules, and configuring the backend to prepare for managing infrastructure as code.

cd /path/to/your/terraform/project
terraform init

terraform plan command in Terraform creates an execution plan that outlines the actions Terraform will take to modify the infrastructure according to the configuration files. It shows the changes, additions, modifications, or deletions of resources without actually applying these changes, allowing users to review and validate the proposed modifications before execution.

Shadowsock + V2Ray

Tue, 06 Sep 2022 21:29:01 +0800

Server Shadowsocks Classic

First uprgade system

apt update && apt uprgade -y

Install need packets

apt install shadowsocks-libev -y

View what your ip address

ip -br a

Edit options parametrs you can change port and all ip "::1", "127.0.0.1" for example “185.85.85.85”

nano /etc/shodowsocks-libev/config.json

{
"server":["::1", "127.0.0.1"],
"mode":"tcp_and_udp",
"server_port":"8388",
"local_port":"1080",
"password":"12345678 ",
"timeout":"60",
"method":"chacha20-ietf-poly1305"
}

{
"server":["185.85.85.85"],
"mode":"tcp_and_udp",
"server_port":"8388",
"local_port":"1080",
"password":"12345678 ",
"timeout":"60",
"method":"chacha20-ietf-poly1305"
}

after change restart service:

service shadowsocks-libev restart

Gitlab

Thu, 01 Sep 2022 21:29:01 +0800

https://gitlab.com/rluna-gitlab/gitlab-ce

For Ubuntu 20.04 and 22.04, arm64 packages are also available and will be automatically used on that platform when using the GitLab repository for installation.

sudo apt-get update
sudo apt-get install -y curl openssh-server ca-certificates tzdata perl

Next, install Postfix (or Sendmail) to send notification emails. If you want to use another solution to send emails please skip this step and configure an external SMTP server after GitLab has been installed

Steam OS

Sun, 01 May 2022 21:29:01 +0800

Installing PORTPROTON:

All command do in terminal

out from mode “Read only”

sudo steamos-readonly disable

Initialize the key

sudo pacman-key --init

Custom Keys

sudo pacman-key -u

adding keys from the repository

sudo pacman-key --populate

Install the .cab unzipping program

sudo pacman -S cabextract

Install dependencies

sudo pacman -Syu bash icoutils wget bubblewrap zstd cabextract bc tar openssl gamemode desktop-file-utils curl dbus freetype2 gdk-pixbuf2 ttf-font zenity lsb-release nss xorg-xrandr vulkan-driver vulkan-icd-loader lsof lib32-freetype2 lib32-libgl lib32-gcc-libs lib32-libx11 lib32-libxss lib32-alsa-plugins lib32-libgpg-error lib32-nss lib32-vulkan-driver lib32-vulkan-icd-loader lib32-gamemode lib32-openssl

Installing the program

wget -c "https://github.com/Castro-Fidel/PortWINE/raw/master/portwine_install_script/PortProton_1.0" && sh PortProton_1.0

Returning “Read-Only” mode

sudo steamos-readonly enable

Simple Linux Routing

Wed, 06 May 2020 21:29:01 +0800

to see all routing

All Routing command

ip route show

for see all routing for ip v6

Routing for ip v6

ip -6 route show

Old command to see routing

Route - an obsolete utility included in the net-tools package. used to display the routing table and build static routes

you need install net-tools (apt install net-tools)

route -n

for v6 ip

route -n -6

routel - its utility for display routing its script for ip route

Windows

Tue, 07 Jan 2020 21:29:01 +0800

IP

free ip address

ipconfig / release

see all ip address

ipconfig / all

renew dns

ipconfig / flushdns

renew ip to other

ipconfig / renew

set DNS to interface

netsh int ip set dns name="name_of_network_interface" static 8.8.8.8 8.8.4.4

fix net reset winsock

netsh winsock reset

Aggregation link in Windows 7-10

Open PowerShell as Administrator:

Get-NetAdapter

Create a New NetSwithTeam

NetSwitchTeam -Name "MyTeam" -TeamMembers "Enternet1", "Enternet2"

to remove

Remove-NetSwitchTeam -Name "MyTeam"

see config

Get-NetSwitchTeam

Wim Capture Image

need external disk image capture to d:\

Nginx

Tue, 18 Jun 2019 00:00:00 +0000

———– redirect site to yandex.ru /etc/nginx/sites-enebled

server listen 80;

server_nane nginx.srwx.net;

return 301 “http://ya.ru”;

test config

nginx -t

curl -D - -o /dev/null -s http://nginx.srwx.net

cat etc/nginx/sites-enabled

nginx reload

Location

location /test {
  return 201 "TEST";
}

password and user

location /restricted {
  auth_basic "Restrictred";
  auth_basic_user_file .htpasswd; 
}

proxy to yandex on main domain

location /admin {
  proxy_pass http://ya.ru;
}

balance beetwen servers

upstream app {
  server 127.0.0.1:8080;
  server 10.10.21.12:8080;
}
server 
  listen 80 default_server;

  server_nane nginx.srwx.net;

  location /admin {
    proxy_pass http://app;
  }
}

Makes the site faster and gives the static css

Linux Basic Command and Map

Sat, 18 May 2019 00:00:00 +0000

Process

all process ps -auxf

see all zombie process ps -aux | grep 'Z'

see systemd ps -p 1

SIGKILL –9 SIGKILL –15

kill -9 PID

Symlink & Hardlink

Symlink example:

ln original_file symlink1

for Read: readlink symlink1

for search find . -type l

for see inode stat original_file

Hardlink example:

ln original_file hardlink1

see number of inode ‘stat original_file’

see how many hardlinks find . -inum 672135

inode - inode is a data structure that stores information about a file or directory in a file system.