linux-and-azure

Moved from https://github.com/spawnmarvel/azure-automation

Set Up a Firewall with UFW on Ubuntu

https://github.com/spawnmarvel/linux-and-azure/blob/main/README_linux_security.md

Azure Linux Ubuntu

Install Azure CLI on Windows

https://learn.microsoft.com/en-us/cli/azure/install-azure-cli-windows?tabs=azure-cli

Run Linux on Windows

Git for Windows provides a BASH emulation used to run Git from the command line. *NIX users should feel right at home, as the BASH emulation behaves just like the "git" command in LINUX and UNIX environments.

https://gitforwindows.org/

mdkdir testfolder

cd testfolder

pwd
# /c/Users/username/testfolder

nano file

$ cat file
#!/bin/bash
echo "we are on windows"
v="my var"
echo "$v"

$ bash file
# we are on windows
# my var

VSC Terminal Shell Integration

By default, the shell integration script should automatically activate on supported shells launched from VS Code.

https://code.visualstudio.com/docs/terminal/shell-integration

Bash it, Git BASH

Git for Windows provides a BASH emulation used to run Git from the command line. *NIX users should feel right at home, as the BASH emulation behaves just like the "git" command in LINUX and UNIX environments.

https://gitforwindows.org/

Bash quick reference

Page1

Page 2

https://github.com/spawnmarvel/quickguides/blob/main/bash/bash.quickref.pdf

References

Linux Shell Scripting Tutorial - A Beginner's handbook http://www.cyberciti.biz/nixcraft/linux/docs/uniqlinuxfeat ures/lsst/ BASH Programming Introduction, Mike G http://www.tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html Advanced BASH Scripting Guide, Mendel Cooper http://tldp.org/LDP/abs/html/

Learn the ways of Linux-fu, for free.

Filesystem Hierarchy

Path	Description
/	- The root directory of the entire filesystem hierarchy, everything is nestled under this directory.
/bin -	Essential ready-to-run programs (binaries), includes the most basic commands such as ls and cp.
/boot -	Contains kernel boot loader files.
/dev -	Device files.
/etc -	Core system configuration directory, should hold only configuration files and not any binaries.
/home -	Personal directories for users, holds your documents, files, settings, etc.
/lib -	Holds library files that binaries can use.
/media -	Used as an attachment point for removable media like USB drives.
/mnt -	Temporarily mounted filesystems.
/opt -	Optional application software packages.
/proc -	Information about currently running processes.
/root -	The root user's home directory.
/run -	Information about the running system since the last boot.
/sbin -	Contains essential system binaries, usually can only be ran by root.
/srv -	Site-specific data which are served by the system.
/tmp -	Storage for temporary files
/usr -	This is unfortunately named, most often it does not contain user files in the sense of a home folder. This is meant for user installed software and utilities, however that is not to say you can't add personal directories in there. Inside this directory are sub-directories for /usr/bin, /usr/local, etc.
/var -	Variable directory, it's used for system logging, user tracking, caches, etc. Basically anything that is subject to change all the time.

ref https://linuxjourney.com/lesson/filesystem-hierarchy

https://linuxjourney.com/

Unix philosphy

ref https://bash.cyberciti.biz/guide/Unix_philosophy

Azure CLI

How to install the Azure CLI

https://learn.microsoft.com/en-us/cli/azure/install-azure-cli

Azure Linux joined to domain login with account

https://learn.microsoft.com/en-us/cli/azure/install-azure-cli-windows?tabs=azure-cli

Powershell (using az cli)

az --version

Log in to a Linux virtual machine in Azure by using Azure AD and OpenSSH

https://learn.microsoft.com/en-us/azure/active-directory/devices/howto-vm-sign-in-azure-ad-linux#configure-role-assignments-for-the-vm

Add IAM on the VM

IAM->Virtual Machine Administrator Login, Reader, Desktop Virtualization Power On Off Contributor
For username@domain.com

az extension add --name ssh
az extension show --name ssh

# login as username@domain.com
az login --tenant  TENANT-ID

az account set --subscription "SUBSSCRIPTION-NAME-VIEW-VM"

az ssh vm -n vmName -g resourceGroupName

# You can now run sudo as username@domain.com

sudo mysql -u root -p

Upgrade AZ CLI

az --version

az upgrade --yes

List of Basic SSH Commands Linux (ubuntu 20.04)

SSH cmds	Description	Example
help	help pwd	help pwd
whatis	Find what a command is used for	whatis ls
sudo apt update	use the apt package management tools to update your local package index
sudo apt update && sudo apt upgrade -y	Make sure all current packages are up to date apt is the command that is being recommended by the Linux distributions.	https://itsfoss.com/apt-vs-apt-get-difference/
apt list --installed	Get installed packages
apt (pacman, yum, rpm)	Package managers depending on the distro
sudo apt install, remove, purge zip	When using the “remove” option, Ubuntu can leave files behind while uninstalling a package. To work around this apt offers another option, the “purge” option.	sudo apt remove zip
sudo apt autoremove	If you want to clean up your Ubuntu system by uninstalling unused packages, then apt offers an option called “autoremove“.	Use 'sudo apt autoremove' to remove it.
whereis	Locate the binary, source, and manual pages for a command	whereis wget, whereis traceroute
which	Identify and report the location of the provided executable	which wget, which traceroute
reboot		sudo shutdown -r now
ls	Show directory contents (list the names of files)	-a (list all + hidden), -l (list all + size)
lsblk	Show disks, The ones with the TYPE disk are the physically attached disks on your computer.	lsblk -o NAME,HCTL,SIZE,MOUNTPOINT
cd	Change dir	cd ./folder
cd /	Get to root directory	(bin boot dev etc home lib lib32 lib64 libx32 lost+found media mnt opt proc root run sbin snap srv sys tmp usr var)
mkdir	Make dir	mkdir folder1
touch	New file	touch file.txt
rm	Remove a file	rm file1
rmdir	Remove a directory, if empty	rmdir folder1
rm -r	To remove a directory and all its contents, including any subdirectories and files	rm -r folder
cat	Show content of file (redirect to var, content=$(cat data.conf))	cat data.conf
pwd	Show current dir: example - >	/home/user
cp	Copy file use if for backup, source destination	cp data.conf data.conf_bck
cp -r	Copy folder, In order to copy a directory on Linux, you have to execute the “cp” command with the “-R” option for recursive and specify the source and destination directories to be copied.	cp -r folder1 folder2
mv	Move file, the difference is that cp will keep the old file(s) while mv won't, source destination	mv myconf.conf myconf.conf_bck = myconf.conf_bck
grep	Search for a string within an output	cat data.conf 'pipe-symbol' grep "uid"
grep	Search for a string in a file	grep -l "espen" file
find	Search files and dirs	find . -name data.conf
nano	Text editor	nano data.conf
head	return specified num of lines from top	head -n 2 data.conf
tail	return specified num of lines from bottom, -f follow	tail -f data.conf
less	Display the contents of a file one page at a time, exit with q	less data.conf
more	Loads the entire file at once, enter for more	more data.conf
diff	find diff between two files	diff data.conf data.conf_bck
cmp	check if two files are identical	cmp data.conf data.conf_identical
comm	combines diff and cmp	comm data.conf data.conf_bck
sort	sort (lines) content of file while outputting	cat names.txt Xavier,Jim, Anna, Bob sort names.txt, Anna, Bob, Jim, Xavier
history	Show last 50 cmds
clear	Clear terminal
echo	Print	var="Hodor", echo $var
man	Access manual pages for all Linux commands	man ls
uname	command to get basic information about the OS	uname -a
hostnamectl	find os name and version	Operating System: Ubuntu 22.04.2 LTS, Kernel: Linux 5.15.0-1040-azur
whoami	Get the active username
export	The export command is specially used when exporting environment variables in runtime	export dbCon="MySql:1245", echo $dbCon
tar	The tar command in Linux is used to create and extract archived files, -cvf compress, -xvf extract	tar -cvf compFolder.tar folder tar -xvf compFolder.ta
gzip	man gzip	d = decompress k = keep comp files also. gzip -dk server.sql.gz, A file compressed with gzip ends with either .gz or .z.
zip	sudo apt install zip	zip -r folder.zip folder1
unzip	sudo apt install unzip	unzip folder.zip, unzip folder.zip -d destinationfolder
ssh	Secure Shell command	ssh user@ipaddress
service	start stop service	service ssh stop
ps	display active proc
ps -aux	display all active proc	ps -aux 'pipe' less
top	View active processes live with their system usage
kill and killall	Kill active processes by process ID or name
df	Display disk filesystem information, -h parameter to make the data human-readable.	df -h
mount	Mount file systems	https://github.com/spawnmarvel/azure-automation/blob/main/azure-extra-linux-vm/READMEQuickstartsLinuxMS.md
chmod	Command to change file permissions, get permission ls - l, -rw-rw-r--	chmod +x file, -rwxrwxr-x or chmod 0755 file
chown	Command for granting ownership of files or folders, command allows you to change the user and/or group ownership of a given file, directory, or symbolic link. get permission and owner, ls -l	chown user-or-userid file1
ifconfig	Display network interfaces and IP addresses	sudo apt install net-tools, eth0:inet private ipaddress
traceroute	Trace all the network hops to reach the destination, sudo apt install traceroute	traceroute www.google.com
telnet	Check connection	telnet ip-address port
nc	The nc (or netcat) utility is used for just about anything under the sun involving TCP, UDP, or UNIX-domain sockets.	nc -zvw10 ip-address 3306
wget	Download files from internet, GNU Wget is a command-line utility for downloading files from the web. With Wget, you can download files using HTTP, HTTPS, and FTP protocols. wget --version, sudo apt install wget	wget https://cdn.zabbix.com/zabbix/binaries/stable/6.0/6.0.3/zabbix_agent-6.0.3-linux-4.12-ppc64le-static.tar.gz
du	Get file size, -h human readble	du -h zabbix_agent-6.0.3-linux-4.12-ppc64le-static.tar.gz
curl	Download or upload data using protocols such as FTP, SFTP, HTTP and HTTPS.	curl www.google.com
sudo	which is an acronym for superuser do or substitute user do, is a command that runs an elevated prompt without a need to change your identity.
sudo -i	A simple way to switch to an interactive session as a root user is the following	root$vmName
su	on the other hand, is an acronym for switch user or substitute user. You are basically switching to a particular user and you need the password for the user you are switching to.
su - bryant	switch to the bryant user account including bryant's path and environment variables, use the (-) switch
sudo ufw enable	By default, when UFW is enabled, it blocks external access to all ports on the server
sudo ufw	Use iptables or ufw to open ports	sudo ufw allow 1022/tcp sudo ufw allow 'Nginx HTTPS'
sudo ufw status	list ufw rules
iptables	Base firewall for all other firewall utilities to interface with. List:	sudo iptables -L
useradd and usermod	Add new user or change existing users data When executed without any option, useradd creates a new user account using the default settings specified in the /etc/default/useradd file. -M, --no-create-home	sudo useradd -m soloman /home/soloman
passwd	To be able to log in as the newly created user, you need to set the user password. The command adds an entry to the /etc/passwd, /etc/shadow, /etc/group and /etc/gshadow files.	sudo passwd soloman
passwd	Create or update passwords for existing users
git --version	Git is likely already installed in your Ubuntu 22.04 server.	# else: sudo apt update, sudo apt install git, git --version
mariadb client	app server	sudo apt install mariadb-client
mariadb	db server	sudo apt install mariadb-server mariadb-client sudo systemctl enable --now mariadb systemctl status mariadb sudo mysql_secure_installation
mysql/mariadb	https://linux.how2shout.com/how-to-install-wordpress-on-ubuntu-22-04-lts-server/	mysql -u USERNAME -h localhost-IP -p db_mydatabase (enter password) sudo mysql -u root -p
IPV6, IPV4	allow remote, /etc/mysql/mariadb.cnf	[mysqld] bind-address = ::, [mysqld] bind-address = 0.0.0.0
crontab	-e, edit, -l display, -v last time edited (must install it)	crontab -e
env	see all system vaiables
echo "$PATH"	print path for a system variable	echo "$HOME"
printf "$PATH\n"	The printf command is just like echo command and is available under various versions of UNIX operating systems. It is a good idea to use printf if portability is a major concern for you.	printf "$HOME\n"
sed	SED command in UNIX stands for stream editor and it can perform lots of functions on file like searching, find and replace, insertion or deletion.	sed -i 's/VAR1=TEST11/VAR1=TEST111/g' test_update.txt

https://www.digitalocean.com/community/tutorials/linux-commands

Script bash, permission and run it

touch myScript.sh
nano myScript.sh
which bash, /bin/bash

#!/bin/bash

echo "Start script"

sleep 3

echo "End script"

Run it

# Run it 1
bash myScript.sh
# Run it 2, Permission denied
./myScript.sh
# Get permission
ls -l
# -rw-r--r-- no execute, add it
sudo chmod +x myScript.sh
# Get permission
ls -l
# -rwxr-xr-r- 
# Run it 3
./myScript.sh

# When we write functions and shell scripts, in which arguments are passed in to be processed, 
# the arguments will be passed int numerically-named variables, e.g. $1, $2, $3
myScript.sh oil gas

# The variable reference, $0, will expand to the current script's name, e.g. my_script.sh

myScript.sh

  GNU nano 6.2                                                                                                          myScript.sh
#!/bin/bash


echo "Input1: $1";
echo "Input2: $2"
### Turn OFF debug mode ###
set +x
# Add more commands without debug mode
result="Combined: $1 and $2"
echo "$result"
echo "cat to var contains:"
rv=$(cat numbers.txt)
echo "$rv"
echo "check sub str in str"
str="Oil is here"
check_it="Oil"
if [[ "$str" =~ .*"$check_it".* ]]; then
   echo "It is here"

Example

Linux Bash Shell Scripting Tutorial Wiki

Bash variables and command substitution

varName=someValue

# Variables
var_a=Hello # (notice no space)
var_b="Hello World"
n=10
inp="/Home/sales/data.txt"
NOW=$(date)
# Referencing the value of a variable

# # not advisable unless you know what the variable contains
echo $var_a 
# use
echo "$var_a"
echo "$var_b"
echo "$n"
echo "$inp"
echo $NOW

Valid variable names

Should start with either an alphabetical letter or an underscore
hey, x9, THESQL_STRING, _secret
Variables names are case-sensitive, just like filenames.

vech=
echo "$vech"

vech=test
echo "$vech"
test

# Generating Output With printf command
# printf does not provide a new line. 
# You need to provide format string using % directives and escapes to format numeric and string arguments in a 
# way that is mostly similar to the C printf() function

# Format control string syntax is as follows:
printf "%w.pL\n" $varName
# w - Minimum field width.
# p - Display number of digits after the decimal point (precision).
# L - a conversion character. , s - String, d - Integer, e - Exponential, f - Floating point

vech="Car"
printf "%s\n" $vech
Car

printf "%s10.5\n" $vech
Car10.5

no=10
printf "%d\n" $no
10

big=5355765
printf "%e\n" $big
5.355765e+06

sales=25.123
printf "%.f\n" $sales
25
printf "%.2f\n" $sales
25.12

Default shell variables value

echo $shellvar

echo ${shellvar:-DefaultValueHere}
DefaultValueHere

# if $ name is not set use default
echo ${shellvar=Terminator 2}
Terminator 2

# if $ unset, set name to default 
echo ${shellvar:=Terminator 2}

echo $shellvar

# The := syntax
# If the variable is an empty, you can assign a default value. The syntax is:
${var:=defaultValue}

The internal field separator

The global variable IFS is what Bash uses to split a string of expanded into separate words
By default, the IFS variable is set to three characters: newline, space, and the tab. If you echo $IFS, you won't see anything because those characters

Quoting

echo "$PATH"
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin

echo /etc/*.conf
/etc/adduser.conf /etc/ca-certificates.conf /etc/debconf.conf /etc/deluser.conf [...]

echo "Path: $PATH"
Path: /usr/local/sbin: [...]

echo 'Path: $PATH'
Path: $PATH

The Backslash

# The backslash ( \ ) alters the special meaning of the ' and " i.e. it will escape or cancel the special meaning of the next character.
\b     backspace
\e     an escape character
\n     new line
\r     carriage return
\t     horizontal tab
\v     vertical tab
\\     backslash
\'     single quote
echo "Pizza bill \$22.5"
echo "CIFS path must be \\\\NT-Server-Name\\ShareName"
echo -e "Sr.no\t DVD (price) "

Export

export backup="/nas10/mysql"
echo "bck $backup"
# list all vlocal vars
export
[...]
declare -x backup="/nas10/mysql"

Getting User Input Via Keyboard and IFS

#!/bin/bash
# Read txt
read -p "Enter db name: " name
read -s -p "Enter password: " my_password
echo "Password: $my_passsord"
echo "Db: $name. Do stuff."

# Read nr
read -p "Enter ID one: " n1
read -p "Enter ID two: " n2
read -p "Enter ID three: " n3
echo "ID : $n1, $n2, $n3"

# IFS, the IFS variable worked as token delimiter or separator.
echo "IFS: $IFS .You will see a whitespace which is nothing but a space, a tab, and a newline (default). "

nameservers="ns1.nixcraft.net ns2.nixcraft.net ns3.nixcraft.net"
echo "$nameservers"
read -r ns1 ns2 ns3 <<< "$nameservers"
echo "DNS #1: $ns1"
echo "DNS #2: $ns2"
echo "DNS #3: $ns3"

# Change IFS separator
pwd="gitevivek:x:1002:1002::/home/gitevivek:/bin/sh"
old="$IFS"
echo "$IFS"
# Set IFS to :
IFS=:
read -r login password uid gid info home shell <<< "$pwd"
echo "$login, $password, $uid, $gid, $info, $home, $shell"

# Array -a
# Set the IFS to split on whitespace
IFS=$'\n'
words="one two three"
read -r -a words <<< "$words"
echo "${words[@]}"

# Make array
arr=("one" "two" "three")
echo "${arr[1]}"

Perform arithmetic operations

#!/bin/bash
# Create an integer variable
declare -i sale=100
declare -i bonus=12
total=$(( sale + bonus))
echo "Total sum int = $total"

# input
# input
read -p "Enter two numbers: " x y
ans=$(( x + y ))
echo "$x + $y = $ans"

https://bash.cyberciti.biz/guide/Main_Page

Setting Up Environment Variables on Ubuntu

# To view all the environment variables
printenv
# or
env

# Setting Environment Variables Temporarily
export MY_VAR="GOT"
printenv MY_VAR

# Setting Environment Variables Permanently
# For system-wide environment variables, edit the /etc/environment file.
sudo nano /etc/environment
MY_VAR="GOT"
# Save and exit the file. For the changes to take effect, either reboot the system or run:
source /etc/environment

# Verify it
printenv
MY_VAR=GOT

# Do a reboot and to be sure and verify it
sudo shutdown -r now
printenv
MY_VAR=GOT

https://tecadmin.net/setting-up-environment-variables-on-ubuntu/

Linux disks and path/folder information

The "thing mentioned"	Description	Example
/dev/sda	The OS disk is labeled,/dev/sda. OS disk should not be used for applications or data. For applications and data, use data disks	https://learn.microsoft.com/en-us/azure/virtual-machines/linux/tutorial-manage-disks *
/dev/sdb	Temporary disks use a solid-state drive that is located on the same Azure host as the VM. Temp disks are highly performant and may be used for operations such as temporary data processing.	mountpoint of /mnt *
/dec/sdc	Data disk(s)	Attach disk at VM creation or Attach disk to existing VM, Prepare data disks, Mount and /etc/fstab
Linux drive letter	Applications and users should not care what SCSI device letter a particular storage gets, because those sdX letters can change and are expected to change. Instead, the storage should be addressed by some unique and permanent property, such as the LUN WWID or filesystem UUID.	https://access.redhat.com/discussions/6004221

Initial Server Setup with Ubuntu 20.04

Step 1 — Logging in as root

The root user is the administrative user in a Linux environment that has very broad privileges.

The next step is setting up a new user account with reduced privileges for day-to-day use.

Once you are logged in as root, you’ll be able to add the new user account. In the future, we’ll log in with this new account instead of root.

Step 2 — Creating a New User

# become root
sudo -i
adduser username
# or
sudo adduser username
# list user
getent passwd username

Step 3 — Granting Administrative Privileges

To avoid having to log out of our normal user and log back in as the root account, we can set up what is known as superuser or root privileges for our normal account.

This will allow our normal user to run commands with administrative privileges by putting the word sudo before the command.

# become root
sudo -i
usermod -aG sudo username
# Now, when logged in as your regular user, you can type sudo before commands to run them with superuser privileges.

# change to user
su - username

# apt install
apt install zip
E: Could not open lock file /var/lib/dpkg/lock-frontend - open (13: Permission denied)
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?
sudo apt install zip

Step 4 — Setting Up a Basic Firewall, UFW, or Uncomplicated Firewall

(

Note: ufw by default is initially disabled. 

ref https://ubuntu.com/server/docs/security-firewall#:~:text=ufw%20%2D%20Uncomplicated%20Firewall,by%20default%20is%20initially%20disabled

Note: using IPV6

ref https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-22-04

)

# Applications can register their profiles with UFW upon installation. These profiles allow UFW to manage these applications by name.
sudo ufw app list
Available applications:
  OpenSSH

# We need to make sure that the firewall allows SSH connections so that we can log back in next time. We can allow these connections by typing:
sudo ufw allow OpenSSH
Rules updated
Rules updated (v6)

# Afterwards, we can enable the firewall by typing:
sudo ufw enable
Command may disrupt existing ssh connections. Proceed with operation (y|n)? y
Firewall is active and enabled on system startup

#
sudo ufw status
Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere
OpenSSH (v6)               ALLOW       Anywhere (v6)

As the firewall is currently blocking all connections except for SSH, if you install and configure additional services, you will need to adjust the firewall settings to allow traffic in.

You can learn some common UFW operations in our https://www.digitalocean.com/community/tutorials/ufw-essentials-common-firewall-rules-and-commands

Step 5 — Enabling External Access for Your Regular User

# Now that we have a regular user for daily use, we need to make sure we can SSH into the account directly.

# 1. If you logged in to your root account using a password, then password authentication is enabled for SSH. 

ssh username@ip-address

# Remember, if you need to run a command with administrative privileges, type sudo before it like this:
sudo command_to_run

# 2. If you logged in to your root account using SSH keys, then password authentication is disabled for SSH. You will need to add a copy of your local public key to the new user’s ~/.ssh/authorized_keys file to log in successfully.

https://www.digitalocean.com/community/tutorials/initial-server-setup-with-ubuntu-20-04

Linux on Azure MS Learn

This comprehensive learning path reviews deployment and management of Linux on Azure. Learn about cloud computing concepts, Linux IaaS and PaaS solutions and benefits and Azure cloud services.

Discover how to migrate and extend your Linux-based workloads on Azure with improved scalability, security, and privacy.

az login --tenant TENANT-ID-HERE

https://github.com/spawnmarvel/azure-automation/blob/main/azure-extra-linux-vm/READMELinuxOnAzure.md

Learn to use Bash with the Azure CLI (quick guide)

Azure CLI reference commands can execute in several different shell environments, but Microsoft Docs primarily use the Bash environment. If you are new to Bash and also the Azure CLI, you will find this article a great place to begin your learning journey. Work through this article much like you would a tutorial, and you'll soon be using the Azure CLI in a Bash environment with ease.

Query results as JSON dictionaries or arrays
Format output as JSON, table, or TSV
Query, filter, and format single and multiple values
Use if/exists/then and case syntax
Use for loops
Use grep, sed, paste, and bc commands
Populate and use shell and environment variables

https://learn.microsoft.com/en-us/cli/azure/azure-cli-learn-bash

Reference az deployment create (Manage Azure Resource Manager template deployment at subscription scope)

https://learn.microsoft.com/en-us/cli/azure/deployment?view=azure-cli-latest#az-deployment-create

Python with cron

Install cron and make it roll 🔵

sudo apt install cron
sudo systemctl enable cron
Synchronizing state of cron.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install enable cron

Cron jobs are recorded and managed in a special file known as a crontab. Each user profile on the system can have their own crontab where they can schedule jobs, which is stored under /var/spool/cron/crontabs/.
To schedule a job, open up your crontab for editing and add a task written in the form of a cron expression. The syntax for cron expressions can be broken down into two elements: the schedule and the command to run.
https://www.digitalocean.com/community/tutorials/how-to-use-cron-to-automate-tasks-ubuntu-1804

script

import time
from datetime import datetime as dt
import logging
import os
import signal
import sys

logging.basicConfig(filename='app.log', filemode='a', format='%(name)s - %(levelname)s - %(message)s', level=logging.INFO)
logging.info('Starting...') # all logging will be logged to app.log
CUR = dt.now()
print(str(CUR), " Starting Cron job") # this will be logged to cron log
MAIN_PID = None

def handler(signum, frame):
    msg = "signal "+ str(signum)
    logging.info(msg)
    exit(1)

signal.signal(signal.SIGINT, handler)

def test_loop():
    rool= True
    count=0
    while (rool):
        count = count +1
        cur_tmp = dt.now()
        logging.info("Python count is " + str(cur_tmp))
        time.sleep(10)
        if count > 2:
            rool=False


if __name__ == "__main__":
    MAIN_PID = os.getpid()
    logging.info(str(MAIN_PID))
    test_loop()
    logging.info("Stopping....")
    cur_tmp = dt.now()
    print(str(cur_tmp), " Ending Cron job") # this will be logged to cron log
    exit(main())

Script

/home/imsdal/run_loop.py
Run the script with python3 run_loop.py
cron log, >> /home/imsdal/cronoutput.log

Set up as cron jobb

crontab -e
# This will ask you which editor choose from. I used nano since it is my favorite editor, 1 = nano.
# Choose 1-4 [1]: 1
* * * * * python3 /home/imsdal/run_loop.py >> /home/imsdal/cronoutput.log
crontab: installing new crontab
# So the first 5 stars you can mention the minute, hour, day and month etc. with command to be executed. 
# Let’s create a cronjob that run every minute with out python script.

Let's view the outpu of each log file

cat cronoutput.log

tail -f cronoutput.log

2023-07-19 23:08:01.284403  Starting Cron job
2023-07-19 23:08:31.315305  Ending Cron job
2023-07-19 23:09:01.424502  Starting Cron job
2023-07-19 23:09:31.455406  Ending Cron job
2023-07-19 23:10:01.554321  Starting Cron job
2023-07-19 23:10:31.585370  Ending Cron job

cat app.log

tail -f app.log

root - INFO - Starting...
root - INFO - 7642
root - INFO - Python count is 2023-07-19 23:08:01.284480
root - INFO - Python count is 2023-07-19 23:08:11.294639
root - INFO - Python count is 2023-07-19 23:08:21.304883
root - INFO - Stopping....
root - INFO - Starting...
root - INFO - 7659
root - INFO - Python count is 2023-07-19 23:09:01.424580
root - INFO - Python count is 2023-07-19 23:09:11.434688
root - INFO - Python count is 2023-07-19 23:09:21.444931
root - INFO - Stopping....
root - INFO - Starting...
root - INFO - 7668
root - INFO - Python count is 2023-07-19 23:10:01.554397
root - INFO - Python count is 2023-07-19 23:10:11.564552
root - INFO - Python count is 2023-07-19 23:10:21.574867
root - INFO - Stopping....
root - INFO - Starting...
root - INFO - 7679
root - INFO - Python count is 2023-07-19 23:11:01.683514

MS Tutorials for Linux

All done:

https://github.com/spawnmarvel/azure-automation/blob/main/azure-extra-linux-vm/READMEQuickstartsLinuxMS.md

Name		Name	Last commit message	Last commit date
Latest commit History 134 Commits
ai-tutorials		ai-tutorials
azure-extra-linux-vm-log-analytics		azure-extra-linux-vm-log-analytics
azure-extra-linux-vm		azure-extra-linux-vm
images		images
the-linux-command-line-william-shotts		the-linux-command-line-william-shotts
.gitignore		.gitignore
README.md		README.md
README_linux_security.md		README_linux_security.md

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Learn the ways of Linux-fu, for free.

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https://www.digitalocean.com/community/tutorials/linux-commands

Script bash, permission and run it

Linux Bash Shell Scripting Tutorial Wiki

Setting Up Environment Variables on Ubuntu

Linux disks and path/folder information

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