中野三玖 dagrons

Useful LXD commands

Summarized from https://stgraber.org/2016/03/19/lxd-2-0-your-first-lxd-container-312/.

Interestingly, the LXD command line client is named.... lxc!

List available containers

lxc image list ubuntu:        # ubuntu: is officially supported image source
lxc image list images:        # images: is an unsupported source
lxc image alias list images:  # lists user-friendly names

Sed Cheat Sheet

sed: stream editor " " vs ' ' 单引号不会执行parameter expansion，但双引号会 sed执行多个命令: sed -i "cmd1; cmd2; cmd3" input.txt $ 表示最后一行

Sed command line options

Common Options

-#, --progress-bar Make curl display a simple progress bar instead of the more informational standard meter.

-b, --cookie <name=data> Supply cookie with request. If no =, then specifies the cookie file to use (see -c).

-c, --cookie-jar <file name> File to save response cookies to.

IDAPython cheatsheet

Important links

Basic commands

Get informations on the binary

Vagrant Cheat Sheet

add image

local

$ vagrant box add {title} {url}
$ vagrant init {title}
$ vagrant up

Tabs and Windows

Function	Shortcut
New Tab	`⌘` + `T`
Close Tab or Window	`⌘` + `W` (same as many mac apps)
Go to Tab	`⌘` + `Number Key` (ie: `⌘2` is 2nd tab)
Go to Split Pane by Direction	`⌘` + `Option` + `Arrow Key`
Cycle iTerm Windows	`⌘` + `backtick` (true of all mac apps and works with desktops/mission control)

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

	[Unit]
	Description=One shot server using netcat
	After=network.target

	[Service]
	Type=simple
	PIDFile=/run/one_shot_server.pid
	Restart=on-failure
	Environment="PORT=4000"
	Environment="FILE=/tmp/somefile.json"

	# Check disk space before
	df -h

	# Delete local-lvm storage in gui

	lvremove /dev/pve/data

	lvresize -l +100%FREE /dev/pve/root

	resize2fs /dev/mapper/pve-root