Al Sunseri alsunseri

install and run AWS linux 2 on home computer as a virtual machine

Detailed Instructions are here : https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/amazon-linux-2-virtual-machine.html ( for VMWare and VirtualBox and Hyoer-V in addiation to KVM )

Instructions sample configs and cloud-init files for on on-premises images: https://cdn.amazonlinux.com/os-images/2.0.20201111.0/

	When changing DNS, host entries, routes etc. Or when testing vpn leaks, etc.
	Also needed when migrating servers


	Windows: Press Win + R and run cmd. Execute command ipconfig /flushdns.
	MacOS: Open Terminal and execute command sudo killall -HUP mDNSResponder.

	Ubuntu: Open Terminal and execute command sudo service network-manager restart.

	You may also need to clear DNS cache in your browser.

	Found: master for n1trux/awesome-sysadmin — A curated list of amazingly awesome open source sysadmin resources. — 3174⭐️ — last updated 14 days ago
	🔎 Checking 407 links
	⚪ https://easybuild.readthedocs.org/en/latest/
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	⚪ https://retspen.github.io
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	⚪ https://phpsysinfo.github.io/phpsysinfo/
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	# lsblk -e7
	# udisksctl info -b /dev/sdXn
	# sudo cryptsetup luksOpen luks-UUID
	> Enter PassPhrase
	# lsblk -e7
	# mkdir /mnt/yada # if needed
	# mount /dev/mapper/qubes_dom0-root /mnt/yada

	[6] pry(main)> require "./db/migrate/20201216202520_add_activity_logging_to_user.rb"
	=> true
	[2] pry(main)> AddActivityLoggingToUser.new.up
	=> nil
	[3] pry(main)> AddActivityLoggingToUser.up
	=> nil
	[4] pry(main)> AddActivityLoggingToUser.new.migrate(:up)
	== AddActivityLoggingToUser: migrating =======================================
	-- add_column(:users, :last_login_from_ip_address, :string, {:default=>nil})
	(1.5ms) ALTER TABLE "users" ADD "last_login_from_ip_address" character varying DEFAULT NULL


	If ssh on - for example, Debian - starts failing to log into a server even though you know you have the right key.
	Also works when you intend to use a password but ssh client fails before allowing that method.
	You can tell the ssh client to ignore the default identity files and only attempt one specific file.

	$ ssh -o 'IdentitiesOnly=yes' -i ~/.ssh/correct_id_file user@host

	IdentitiesOnly
	Specifies that ssh(1) should only use the authentication identity and certificate files explicitly configured
	in the ssh_config files or passed on the ssh(1) command-line,

	#!/usr/bin/env bash
	# blockdev is in the util-linux package and the binary is in /sbin usually
	# util-linux: /sbin/blockdev

	# Display an error message if the partition (input) is not
	# Exit the shell script with a status of 1 using exit 1 command.
	[ $# -eq 0 ] && { echo "Usage: $0 partion"; exit 1; }

	PARTITION=$1
	/sbin/blockdev --getbsz $PARTITION

	#!/usr/bin/env bash

	# Display an error message if the command does not include a filename
	# Exit the shell script with a status of 1 using exit 1 command.
	[ $# -eq 0 ] && { echo "Usage: $0 certfilename"; exit 1; }


	CERTFILE=$1
	openssl x509 -noout -serial -in $CERTFILE
	# for formatting the output in quad see


	Debian desktop vms add swap partitions at the end of the virtual /dev/vda drive.
	In order to take advantage of new space added via virsh one has to take the swap partition into account.

	The new space will be added after the extended and swap partition so to speak.

	So before growpart will work one has to move the swap partiion to the end of the disk.
	Then vda1 can grow up to the start of the new extended or swap partition

	Several methods depending on the implementation of grep or whether the grep needs to be scripted etc.

	1: If grep comes compiled with perl regex support use 'grep -P '
	grep -P "\t" filelist
	embedded in a pattern:
	grep -P "^1.1G\t" /tmp/du-h-output.txt

	2 this is neat - grep -G $'\t'
	it works in larger patterns as well:
	grep -G "^1.1G"$'\t' /tmp/du-h-output.txt