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snippets

Some pieces of code I find useful for some reason.

Bash

  • install -DTvm600 src.txt dst.txt, install -Tvm700 src.sh dst.sh
  • install -vm600 -t ~/.ssh mykey_ed25519
  • install -omyuser -gmygroup -dvm700 mydir, install -dv -omyuser -gmygroup mydir
  • tmux new-session -As0
  • tmux setw -g mouse on
  • eval "$(ssh-agent)", ssh-add -t1800 (30 minutes), ssh-add -l, eval "$(ssh-agent -k)"
  • git init -bmain myrepo, git init --bare -bmain myrepo.git
  • git log --graph --oneline
  • git fsck --strict
  • git clone --depth=1 ...
  • git tag v1.2.3 && git push --tags
  • git diff --no-index dir1/ dir2/
  • git diff --cached > my.patch, git apply my.patch
  • git diff --quiet HEAD^ HEAD -- .
  • git clean -dfnX
  • git remote set-url origin git@github.com:octocat/hello-world.git
  • git config --global credential.helper "cache --timeout=$((10*365*24*60*60))"
  • git lfs track '*.mp3', git lfs ls-files
  • reporoot=$(git rev-parse --show-toplevel)
  • latest_commit=$(git rev-parse HEAD)
  • grep -IRi --exclude-dir=.git pattern
  • tig, tig blame myfile.txt
  • type python3
  • unset HISTFILE
  • tar -cvzf myarchive.tar.gz mydir, tar -xvzf myarchive.tar.gz
  • tar -cvzf myarchive.tar.gz -g snapshot.snar -C mydir ., tar -xvzf myarchive.tar.gz -g snapshot.snar -C mydir
  • curl --skip-existing -fLO https://..., curl -fLo target.zip https://...
  • curl -I https://example.com/, curl -i https://example.com/
  • top and then press xcV. Then W to save the config
  • cd "$(dirname "$0")" or basedir=$(dirname "$0"), useful in a Bash script
  • sudo blkid -sUUID -ovalue /dev/sdb1
  • ffmpeg -i input.mp4 -ss 97 -t 10 output.mp4
  • ffmpeg -i input.jpg -vf 'scale=iw*1/2:ih*1/2' output.jpg
  • ( ow=640; oh=360; ffmpeg -i input.mp4 -vf "scale=$ow:$oh:force_original_aspect_ratio=decrease,pad=$ow:$oh:(ow-iw)/2:(oh-ih)/2" output.mp4 )
  • for i in *.mp3; do echo "$i"; ffmpeg -i "$i" -af volumedetect -vn -sn -dn -f null /dev/null 2>&1 | grep -E '^\[Parsed_volumedetect.+_volume: .+$'; done
  • ffmpeg -i input.mp3 -filter:a 'dynaudnorm=p=0.9:s=5' output.mp3
  • ffmpeg -i input.mp3 -map 0:a -c:a copy -map_metadata -1 output.mp3
  • watch -n.2 date, watch -pn3 'date && sleep 2'
  • scp myfile.txt user@hostname:/home/user/myfile.txt
  • ipfs daemon &, jobs, fg 1, kill %1
  • nohup ping localhost > myoutput.txt & disown, pgrep -fx 'ping localhost', pkill -fx 'ping localhost', nohup sleep infinity >/dev/null 2>&1 & disown
  • pgrep -fxu"$EUID" '^python3 '"$HOME"'/myscript\.py$'
  • find mydir -mindepth 1 -printf '%y %T@ %#m %s %P\n' | LC_ALL=C sort -k5
  • find mydir -type d -printf 'DIR -1 %P/\n' -o -type f -printf '%T@ %s %P\n' | LC_ALL=C sort -k3
  • find . -type f -exec sha256sum {} +
  • tree -apughD --inodes
  • find . | grep -i pattern, find . -iname '*pattern*'
  • find . \( \( -type d \! -perm 755 \) -o \( -type f \! -perm 644 \) \) -exec ls -dl {} +
  • find . \( -type d -perm 775 -exec chmod 755 {} \; \) -o \( -type f -perm 664 -exec chmod 644 {} \; \)
  • git ls-files --full-name '*pattern*'
  • git ls-files | xargs -rd\\n sha256sum
  • cp -Rvt/media/destdisk /media/sourcedisk/mydir
  • ss -tulpn
  • df -h
  • free -htvw
  • du -sh
  • file -b --mime-type myfile.txt, xdg-mime query filetype myfile.txt
  • stat -c%Y myfile.txt, stat -c%s myfile.txt
  • zip -r myarchive.zip mydir, unzip -oq myarchive.zip -d mydir
  • 7z a myarchive.7z mydir, 7z a myarchive.zip mydir, 7z a dummy -tzip -so mydir > myarchive.zip
  • 7z e myarchive.7z mydir/myfile.txt -so
  • 7z l myarchive.7z
  • 7z x -aoa myarchive.7z, 7z x myarchive.7z -osomedir, 7z x myarchive.7z -o\*
  • date -ur myfile.txt +%Y-%m-%d-%H%M%S, date +%s, date +%s.%N, date -Ins
  • less myfile.txt
  • last, lastb, lastlog
  • IFS= read -rsp 'Password: ' MYPASSWORD && export MYPASSWORD, set -o ignoreeof; exit() { echo 'Use "builtin exit" to exit'; }
  • read -rsp 'Press ENTER to continue...'; echo
  • diff <(ls -l) <(ls -la)
  • ps -aux --sort -pcpu | head -n10
  • strings /proc/1234/environ | grep -i MY_ENV_VAR
  • export SSH_AUTH_SOCK=/run/user/$UID/keyring/ssh
  • SSH_AUTH_SOCK= ssh myuser@192.168.0.123
  • python3 -mhttp.server
  • php -S 127.0.0.1:8080 -t mydir
  • dig @ns1.example.com www.example.com
  • git pull --no-edit && git add . && { git commit "-m$(date +%s)" || :; } && git push
  • find . -type d -name .git -prune -printf '%h\n', find . -type d -exec test -d '{}/.git' \; -prune -print
  • git describe --tags --exact-match, git describe --tags --dirty
  • [ -z "$(git status -s)" ]
  • git reset --soft HEAD^ && git push --force
  • git log --follow --format=%H myfile.txt | while IFS= read -r i; do echo -n "$i,$(git show -s --format=%aI "$i"),"; grep -ci 'mypattern' <(git cat-file -p "$i:./myfile.txt"); done
  • ssh-keygen -t ed25519 -C mydevice -f ~/.ssh/id_ed25519, ssh-keygen -t rsa -b 4096 -C mydevice -f ~/.ssh/id_rsa
  • ssh-keygen -yf ~/.ssh/id_ed25519
  • ssh-copy-id myuser@192.168.0.123
  • ssh-keygen -R [myserver.example.com]:2222
  • ssh-keygen -lf <(cat /etc/ssh/ssh_host_*_key.pub), ssh-keygen -lF '[192.168.0.123]:2222'
  • ansible-playbook -Kk -i hosts.yml playbook.yml -t tags --list-tasks
  • withprefix() { while IFS= read -r i; do echo "$1$i"; done }
  • echo Message | mail -s Subject recipient@example.com
  • iostat -o JSON
  • S_COLORS=always watch -dpn.5 --color iostat
  • systemctl -a | grep -Fi myunit (-a = also dead ones), systemctl list-unit-files | grep -Fi myunit (also disabled ones)
  • systemctl is-active -q myunit; echo $?
  • systemctl list-timers
  • systemd-analyze calendar '*-*-* 6,18:00' --iterations 10
  • : "${myvar:=myvalue}", export MY_ENV_VAR="${MY_ENV_VAR:-myvalue}"
  • socat - TCP:example.com:80
  • socat UNIX-LISTEN:/tmp/my.sock,mode=666,fork,unlink-early -, date | socat - UNIX-CONNECT:/tmp/my.sock
  • export XDG_RUNTIME_DIR=/run/user/$UID to use systemctl --user as a linger-enabled user
  • nano -Sav filename, vim -R filename
  • nano -AEJ80 -ST4 -ailmq filename
  • vboxmanage startvm myvm --type=headless
  • vboxmanage controlvm myvm acpipowerbutton
  • while IFS= read -r i; do vboxmanage controlvm myvm keyboardputstring "$i"; vboxmanage controlvm myvm keyboardputscancode 1C 9C; done
  • vboxmanage getextradata global GUI/SuppressMessages, vboxmanage setextradata global GUI/SuppressMessages all
  • echo 'Hello $USER!' | envsubst
  • sudo tcpdump -wfile.pcap, termshark -rfile.pcap
  • curl -fsSL https://sh.rustup.rs/ | RUSTUP_INIT_SH_PRINT=arch bash
  • bash <(curl -fsSL https://sh.rustup.rs/) -y && . ~/.cargo/env, rustup update, cargo install rust-script
  • export RUSTUP_HOME=~/my-portable-rust/rustup CARGO_HOME=~/my-portable-rust/cargo, bash <(curl -fsSL https://sh.rustup.rs/) -y --no-modify-path, ~/my-portable-rust/cargo/bin/cargo run
  • mkfifo mypipe; while :; do date | tee mypipe; done
  • date | curl -sSXPOST "https://api.telegram.org/bot${1#bot}/sendMessage" -dchat_id="$2" --data-urlencode text@- --fail-with-body -w'\n'
  • for i in 192.168.0.1{01..19}; do ping "$i" & done | grep -i 'bytes from .*: icmp_seq='
  • find . -iname \*.mp3 -printf '%P\n' | ( echo '#EXTM3U'; while IFS= read -r i; do bn=${i##*/}; echo "#EXTINF:0,${bn%.*}"; echo "file://$HOME/Music/$i"; done )
  • for i in var_01 VAR_02; do IFS= read -rsp "$i: " "${i?}"; if [[ "$i" = [[:upper:]]* ]]; then export "${i?}"; fi; done
  • shuf -en1 Alice Bob Carl, shuf -i1-10 -n1
  • tr -cd '0-9A-Za-z' < /dev/random | head -c64; echo, tr -cd ' -~' < /dev/random | head -c64; echo, tr -cd '0-9a-f' < /dev/random | for i in {1..10}; do head -c8; echo; done | LC_ALL=C sort -u | shuf
  • myvar=$'string \\ with\nsome\nspecial \'chars\' to "escape"'; echo "${myvar@Q}"
  • venv/bin/python3 -mpip install -U --progress-bar=off -r requirements.txt
  • escape_if_any() { echo "${1:+${1@Q}}"; }
  • json_min_escape() { jq -c . | jq -Rrs 'rtrimstr("\n") | @json'; }
  • arr=(one two 'three four'); escaped_items=("${arr[@]@Q}"); echo "${escaped_items[0]}"; escaped_str="${arr[*]@Q}"; echo "$escaped_str"
  • bash -ec 'echo "${0@Q} - ${*@Q}"' bash hey 'hello world'
  • mapfile -t arr < <(echo 'hey "hello world"' | xargs -n1)
  • printf '%s\n' "${arr[@]}"
  • vlc -vvv -Idummy --no-audio screen:// --screen-fps=10 --sout='#transcode{vcodec=MJPG,scale=0.5}:standard{access=http,mux=mpjpeg,dst=:8080/}' --sout-http-mime='multipart/x-mixed-replace;boundary=--7b3cc56e5f51db803f790dad720ed50a' --live-caching=100
  • modprobe -r mymod01 mymod02, printf 'blacklist %s\n' mymod01 mymod02 > /etc/modprobe.d/blacklist-mymod.conf
  • printf 'blacklist %s\n' uas usb_storage > /etc/modprobe.d/blacklist-usb-storage.conf
  • bind -x '"\e": mycommand'
  • sudo iptables -nvL
  • sudo iptables -t nat -F OUTPUT
  • curl https://api.ipify.org/
  • ping my.dns.domain.10-0-0-1.nip.io, ping my.dns.domain.lvh.me
  • socat TCP4-LISTEN:9000,fork,reuseaddr /dev/null, dd if=/dev/zero bs=1M count=1024 status=progress | socat - TCP:192.168.0.2:9000
  • curl -fLo ~/.local/bin/proot https://proot.gitlab.io/proot/bin/proot && chmod +x ~/.local/bin/proot
  • curl -fLo ~/.local/bin/kubectl "https://dl.k8s.io/release/$(curl -fsSL https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl" && chmod +x ~/.local/bin/kubectl
  • curl -fL https://get.helm.sh/helm-v3.17.2-linux-amd64.tar.gz | tar -xvz --strip-components=1 -C ~/.local/bin linux-amd64/helm
  • curl -fL https://github.com/derailed/k9s/releases/download/v0.40.10/k9s_Linux_amd64.tar.gz | tar -xvzC ~/.local/bin k9s
  • curl -fL https://downloads.rclone.org/rclone-current-linux-amd64.zip | bsdtar -xOf- 'rclone-*-linux-amd64/rclone' | install -Tv /dev/stdin ~/.local/bin/rclone
  • curl -fL https://github.com/restic/restic/releases/latest/download/restic_0.18.0_linux_amd64.bz2 | bunzip2 -c | install -Tv /dev/stdin ~/.local/bin/restic
  • curl -fLo/tmp/rustdesk.deb https://github.com/rustdesk/rustdesk/releases/download/1.4.2/rustdesk-1.4.2-x86_64.deb && sudo apt-get update && sudo apt-get install -y libegl1 /tmp/rustdesk.deb
  • curl -fLo/tmp/rpi-imager.deb https://downloads.raspberrypi.com/imager/imager_latest_amd64.deb && sudo apt-get update && sudo apt-get install -y /tmp/rpi-imager.deb
  • rustdesk --get-id, sudo rustdesk --password MyPassword1234 (while RustDesk is running)
  • sudo dd if=/dev/mmcblk2 status=progress | gzip -c | split -b4GB - mmcblk2.img.gz.part
  • md5sum mmcblk2.img.gz.part* > MD5SUMS
  • cat mmcblk2.img.gz.part* | gunzip -c | sudo dd of=/dev/mmcblk2 status=progress
  • sudo parted /dev/sdb -s 'mklabel gpt mkpart "" 0% 100%', sudo mkfs.ext4 /dev/sdb1 -L mylabel
  • fallocate -vl1G myimage.img
  • dd if=/dev/random of=myimage.img bs=1M count=1024 status=progress
  • gzip -tv myfile.txt.gz
  • dpkg -s python3, dpkg -l | grep -Fi pyth
  • comm --nocheck-order --total <(echo -e 'common\nonlyleft') <(echo -e 'common\nonlyright')
  • sunodl() { curl -fLO https://cdn1.suno.ai/$1.mp3; }
  • install -DTv <(echo -e '#!/bin/bash\nexec "$(realpath "$(dirname "$0")/../Scripts/python")" "$@"') venv/bin/python3
  • shred -u myfile.txt
  • gpg -ac --cipher-algo=AES256 --no-symkey-cache -o encrypted.asc <(date), gpg -d --no-symkey-cache encrypted.asc
  • date | gpg -ac --batch --cipher-algo=AES256 --no-symkey-cache --passphrase-file=<(echo MyPassphrase) -o encrypted.asc, gpg -d --batch --no-symkey-cache --passphrase=MyPassphrase encrypted.asc | sha256sum
  • gpg --list-packets encrypted.asc, gpg -q --list-packets encrypted.asc >/dev/null
  • gpgconf -v --list-options gpg-agent
  • echo -e 'default-cache-ttl 0\nmax-cache-ttl 0' >> ~/.gnupg/gpg-agent.conf && gpgconf --reload
  • rsync -Phavn --delete --stats ~/sourcedir/ ~/targetdir/ (trailing slashes needed!)
  • exec 3<<<mypassword; restic -r my-restic-repo -p/dev/fd/3 init; exec 3<&-
  • env -C myfiles restic -r "$(realpath my-restic-repo)" -p<(echo mypassword) backup -vn --skip-if-unchanged .
  • export RESTIC_REPOSITORY="$(realpath my-restic-repo)" RESTIC_PASSWORD=mypassword
  • restic snapshots, restic ls -l latest, restic check --read-data
  • restic restore latest --delete -vvt myfiles --dry-run
  • restic dump latest / -t myarchive.tar
  • restic -r sftp://myuser@192.168.0.123:2222//my-restic-repo snapshots
  • mkdir -v mymountpoint && restic mount mymountpoint, cat mymountpoint/snapshots/latest/myfile.txt
  • restic snapshots latest --json | jq -r '.[0].id'
  • restic diff --metadata a1b2 c3d4
  • GPG_TTY=$(tty) restic --password-command='gpg -dq encrypted.asc' snapshots (to make pinentry-curses work)
  • RCLONE_CONFIG=rclone.conf rclone config, rclone config --config=rclone.conf
  • RCLONE_CONFIG= rclone config file, rclone --config= config file
  • echo -e '[mygdrive]\ntype = drive\nscope = drive\nroot_folder_id = ...' > ~/.config/rclone/rclone.conf, rclone config reconnect mygdrive:
  • echo -e "[mycrypt]\ntype = crypt\nremote = mygdrive\npassword = $(echo mypass | rclone obscure -)" >> ~/.config/rclone/rclone.conf
  • rclone lsf myremote:
  • rclone --config= lsf -R --format=pst --time-format=unixnano . | sed -E 's/\/;-1;[^;]+$/\/;-1;DIR/' | LC_ALL=C sort -t\; -k1,1
  • rclone sync -vn --create-empty-src-dirs myremote:/remote-src-dir ./local-dst-dir
  • rclone --config= sync -Mvn --create-empty-src-dirs --files-from=mylist.txt ./src-dir ./dst-dir
  • export RCLONE_FTP_PASS=$(IFS= read -rsp 'Password: ' && echo "$REPLY" | rclone obscure -), rclone --config= sync -vn --create-empty-src-dirs ./www :ftp:/ --ftp-host=myserver.example.com --ftp-user=myuser --ftp-ask-password --ftp-explicit-tls --ftp-no-check-certificate --size-only
  • rclone --config= sync -vn --create-empty-src-dirs . :sftp,host=192.168.0.123,port=2222,user=myuser:mydir
  • rclone check -v --size-only myremote:/remote-src-dir ./local-dst-dir
  • rclone --config= serve -v sftp --dir-cache-time=0 --user=myuser --pass=mypass --read-only .
  • rclone --config= serve -v sftp --dir-cache-time=0 --addr=0.0.0.0:2022 --user=myuser --authorized-keys=<(echo 'ssh-ed25519 AAAAC3Nza...') .
  • rclone --config= serve -v webdav --dir-cache-time=0 --disable-dir-list --addr=unix:///tmp/my.sock .
  • curl -fsSL https://api.github.com/repos/OWNER/REPO/releases/latest | sed -En 's/^ "name": "([^"]+)",$/\1/p'
  • ssh -oServerAliveInterval=30 -oExitOnForwardFailure=yes myuser@192.168.0.123 -p2222 -NvR80:/tmp/my.sock
  • ssh -oServerAliveInterval=30 -oExitOnForwardFailure=yes myuser@192.168.0.123 -p2222 -NvL/tmp/my.sock:127.0.0.1:8080
  • ssh -oServerAliveInterval=30 -NvMS~/.ssh/cm-%C myuser@192.168.0.123, ssh -S~/.ssh/cm-%C myuser@192.168.0.123
  • ssh -oServerAliveInterval=30 -NfMS~/.ssh/cm-%C myuser@192.168.0.123, ssh -S~/.ssh/cm-%C myuser@192.168.0.123 -Oexit
  • ssh -GS~/.ssh/cm-%C myuser@192.168.0.123 | sed -En 's/^ControlPath\s+(.+)$/\1/Ip'
  • ssh -Jmyjumpuser@myjumphost.example.com:2222 myuser@192.168.0.123
  • LC_ALL=C grep --color '[^ -~]' myfile.txt, LC_ALL=C sed -i 's/[^ -~]/?/g' myfile.txt
  • sed -Ei 's/^#?force_color_prompt=.*$/force_color_prompt=yes/' ~/.bashrc
  • sed -Ei 's/^(\s+)#\s*(alias [ef]?grep='\''[ef]?grep --color=auto'\'')/\1\2/' ~/.bashrc
  • { base64 -w256 myfile.txt; echo; echo 'Hello, World!'; } | { while IFS= read -r i; do [ -n "$i" ] || break; echo "$i"; done | base64 -d | cat -A; cat -A; }
  • bn=${path##*/} (similar to basename "$path"), dn=${path%/*} (similar to dirname "$path")
  • gtk-launch myapp.desktop
  • update-desktop-database -v ~/.local/share/applications, xdg-desktop-menu forceupdate
  • gnome-session-inhibit --app-id org.gnome.Terminal.desktop --reason 'Unsaved work' --inhibit logout:suspend --inhibit-only
  • dconf watch /, dconf dump /, dconf write /org/gtk/gtk4/settings/file-chooser/show-hidden true
  • gsettings list-recursively, gsettings list-schemas --print-paths
  • gsettings describe org.gtk.gtk4.Settings.FileChooser show-hidden
  • gsettings set org.gtk.gtk4.Settings.FileChooser show-hidden true
  • powerprofilesctl set power-saver
  • xdg-mime query default audio/mpeg, xdg-mime default vlc.desktop audio/mpeg video/mp4, cat ~/.config/mimeapps.list, grep '^MimeType=' /usr/share/applications/vlc.desktop
  • inotifywait -cmqr mydir, inotifywait -eMODIFY,ATTRIB,CLOSE_WRITE,MOVE,MOVE_SELF,CREATE,DELETE,DELETE_SELF,UNMOUNT -t10 myfile.log
  • [ -z "$(lsof +D mydir)" ]
  • echo 'rename oldname newname' | sftp -b- -oControlPath=~/.ssh/cm-%C -P2222 myuser@192.168.0.123
  • coproc MYPROC { pinentry-gnome3; }; echo -e 'SETPROMPT My prompt\nGETPIN\nBYE' >&"${MYPROC[1]}"; sed -En 's/^D (.+)$/\1/p' <&"${MYPROC[0]}"
  • upower -e, upower -i /org/freedesktop/UPower/devices/battery_BAT0 | grep -E '^\s+energy-full\S*:', upower -d
  • fdo_notify() { gdbus call --session --dest=org.freedesktop.Notifications --object-path=/org/freedesktop/Notifications --method=org.freedesktop.Notifications.Notify -- "$1" 0 "$2" "$3" "$4" '[]' '{}' -1; } (see https://specifications.freedesktop.org/notification-spec/1.3/protocol.html#command-notify), fdo_notify MyApp folder-open MyTitle MyText, fdo_notify MyApp ~/myicon.png MyTitle MyText
  • wine reg add 'HKLM\SOFTWARE\MyApp' /v MyValue /t REG_SZ /d MyData /f /reg:64 (the /reg:64 part is required for Wine, otherwise the value would be created under HKLM\SOFTWARE\Wow6432Node\...)
  • inkscape --export-filename=myimage.png --export-type=png myimage.svg
  • printf '%s\n' GRUB_TIMEOUT_STYLE=countdown GRUB_TIMEOUT=3 | install -Tvm644 /dev/stdin /etc/default/grub.d/timeout.cfg && update-grub
  • fwupdmgr get-updates
  • udisksctl status, udisksctl loop-setup -rf myimage.img, udisksctl mount -b /dev/loop0 -o ro, udisksctl unmount -b /dev/loop0, udisksctl loop-delete -b /dev/loop0
  • sudo nmap -Pn -n -p- -A -T4 -vv 192.168.0.0/24 and then you can press ? to print a runtime interaction help screen
  • echo 100/3 | bc -l
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install -Tvm600 <(echo 'ACTION=="add", SUBSYSTEM=="pci",' \
    'ATTR{vendor}=="0x1234", ATTR{device}=="0x5678", ATTR{remove}="1"') \
    /etc/udev/rules.d/99-disable-pci-example.rules
udevadm trigger -vcadd -spci -avendor=0x1234 -adevice=0x5678
install -Tvm600 <(echo 'ACTION=="add", SUBSYSTEM=="usb",' \
    'ATTR{idVendor}=="1a2b", ATTR{idProduct}=="3c4d", ATTR{remove}="1"') \
    /etc/udev/rules.d/99-disable-usb-example.rules
udevadm trigger -vcadd -susb -aidVendor=1a2b -aidProduct=3c4d
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readonly user_id=1001 user_name=myuser

loginctl enable-linger "$user_name"
for i in {10..1}; do
    [ -e "/run/user/$user_id/systemd/private" ] && break
    echo "Waiting for systemd user session to initialize (max ${i}s)"
    sleep 1
done
[ -e "/run/user/$user_id/systemd/private" ] ||
    { echo 'Timeout waiting for systemd user session' >&2; exit 1; }
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fallocate -vl1G myimage.img
/usr/sbin/mkfs.ext4 myimage.img

sudo mkdir -v /mnt/myimage
sudo mount -v myimage.img /mnt/myimage

sudo umount -v /mnt/myimage
sudo rmdir -v /mnt/myimage

sudo apt update && sudo apt install -y fuse2fs

mkdir ~/myimage
fuse2fs myimage.img ~/myimage

fusermount -u ~/myimage
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gpg --full-gen-key

gpg --batch --gen-key << 'EOF'
Key-Type: EDDSA
Key-Curve: ed25519
Key-Usage: sign
Subkey-Type: ECDH
Subkey-Curve: cv25519
Subkey-Usage: encrypt
Passphrase: abc
Name-Real: mykey
Expire-Date: 0
%commit
EOF

gpg -k && gpg -K

gpg --passwd mykey

gpg -er mykey myfile.txt; gpg -do myfile.txt myfile.txt.gpg
date | gpg -aer mykey -o mymsg.txt.asc; gpg -d mymsg.txt.asc

gpg -ao mykey-pub.asc --export mykey; gpg -ao mykey-sec.asc --export-secret-key mykey
gpg --import mykey-pub.asc mykey-sec.asc

gpg --export-ownertrust > otrust.txt
rm ~/.gnupg/trustdb.gpg && gpg --import-ownertrust otrust.txt
gpg --edit-key 0123456789ABCDEF0123456789ABCDEF01234567 trust quit
echo '0123456789ABCDEF0123456789ABCDEF01234567:6:' | gpg --import-ownertrust

gpg --delete-secret-and-public-key mykey
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# In case of swapfiles it's better to use "dd" to fill the file with actual zeros, rather than "fallocate", due to potential issues with older kernels
sudo dd if=/dev/zero of=/swapfile-additional bs=1M count=10240 status=progress
sudo chmod 600 /swapfile-additional
sudo mkswap /swapfile-additional

sudo swapon /swapfile-additional; sudo swapoff /swapfile-additional

echo '/swapfile-additional none swap sw 0 0' | sudo tee -a /etc/fstab
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# Inspired by https://wiki.debian.org/DebianUnstable#Installation

sudo cp -Tv /etc/apt/sources.list{,.old-$(date +%Y-%m-%d-%H%M%S)}

sudo tee /etc/apt/sources.list << 'EOF'
deb http://deb.debian.org/debian/ unstable main non-free-firmware
deb-src http://deb.debian.org/debian/ unstable main non-free-firmware
EOF

sudo apt update && sudo apt full-upgrade
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# Warning: this is just an example. You should never write plain passwords in commands
hash_pbkdf2=$({ echo mypassword; echo mypassword; } | grub-mkpasswd-pbkdf2)
hash_pbkdf2=$(echo "$hash_pbkdf2" | grep -o 'grub\.pbkdf2\..*')

sudo install -Tvm700 /dev/stdin /etc/grub.d/01_psw << EOF
#!/bin/sh
exec tail -n+3 "\$0"
set superusers="root"
password_pbkdf2 root $hash_pbkdf2
EOF

sudo sed -Ei 's/^(\s+echo "menuentry .+ \$\{CLASS\} )(\\\$menuentry_id_option '\''gnulinux-simple-.+)$/\1--unrestricted \2/' /etc/grub.d/10_linux

sudo update-grub

Shell snippets for Docker

  • docker run -it --rm --log-driver=none docker.io/library/debian:12
  • docker run -d --name=mydeb01 docker.io/library/debian:12 sleep infinity, docker exec -it mydeb01 bash, docker rm -f mydeb01
  • docker ps -a --format {{.Names}}
  • docker rm -fv mycontainer
  • docker run --rm -v myvolume:/v --log-driver=none docker.io/library/busybox tar -cvzC/v . > mybackup.tar.gz
  • docker run --rm -v myvolume:/v -i docker.io/library/busybox tar -xvzC/v < mybackup.tar.gz
  • docker create --name=tmp01 docker.io/library/busybox
  • docker cp tmp01:/bin - | gzip -c > mybin.tar.gz
  • docker cp tmp01:/bin/sh - | tar -xv
  • docker rm -v tmp01
  • docker run -d --name=mydind01 --privileged docker.io/library/docker:dind
  • docker run -it --rm -v /var/run/docker.sock:/var/run/docker.sock --log-driver=none docker.io/wagoodman/dive docker.io/library/python:3
  • docker-compose down -v && docker-compose up -d --build && docker-compose logs -ft
  • docker-compose exec mycontainer bash
  • docker run -it --rm -p8080:8080 -v "$PWD:/v" php:8 -S '0.0.0.0:8080' -t /v
  • docker run --rm -v "$PWD:/v" -u "$(id -u):$(id -g)" ghcr.io/plantuml/plantuml -tsvg /v
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docker build -t img-sshsrv01:latest - << 'EOF'
FROM docker.io/library/debian:12
RUN apt-get update && \
    apt-get install -y sudo openssh-server && \
    rm -rf /var/lib/apt/lists/* && \
    mkdir -p /run/sshd
# Warning: leaving the generated host keys in place!
EXPOSE 22
RUN useradd -UGsudo -ms/bin/bash mainuser && \
    echo 'mainuser ALL=(ALL) NOPASSWD: ALL' | \
        install -Tvm440 /dev/stdin /etc/sudoers.d/mainuser-nopassword && \
    echo mainuser:changeme | chpasswd # Warning: very bad password!
ENTRYPOINT ["/usr/sbin/sshd", "-De"]
EOF

docker run -d --name=sshsrv01 -p2222:22 img-sshsrv01:latest
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docker build -t img-unpriv01:latest - << 'EOF'
FROM docker.io/library/debian:12
RUN apt-get update && \
    apt-get install -y sudo \
        git nano tmux tree wget zip curl socat procps jq \
        iputils-ping iproute2 && \
    rm -rf /var/lib/apt/lists/*
RUN useradd -UGsudo -ms/bin/bash mainuser && \
    echo 'mainuser ALL=(ALL) NOPASSWD: ALL' | \
        install -Tvm440 /dev/stdin /etc/sudoers.d/mainuser-nopassword && \
    echo mainuser:changeme | chpasswd # Warning: very bad password!
USER mainuser
ENV USER=mainuser HOME=/home/mainuser
WORKDIR /home/mainuser
EOF

docker run -d --name=unpriv01 img-unpriv01:latest sleep infinity

Shell snippets for Podman

  • sudo XDG_RUNTIME_DIR=/run/user/1001 -iu myuser
  • podman ps -ap
  • podman ps -qfname=mycontainer; echo $?
  • systemctl --user status podman-kube@$(systemd-escape ~/kube.yaml)
  • journalctl --user -u podman-kube@$(systemd-escape ~/kube.yaml)
  • ls -la ~/.local/share/containers/storage/volumes
  • (IFS= read -rsp 'Password: ' && echo -e "{\"main\":\"$(echo -n "$REPLY" | base64 -w0)\"}") | podman secret create mypassword -
  • echo -e "{\"main\":\"$(base64 -w0 mykey.pem)\"}" | podman secret create mykey -
  • podman image ls -a, podman image prune -af

Shell snippets for Kubernetes

  • kubectl get all -A, kubectl get pod -owide, kubectl get pod -w
  • kubectl run mypod --image=docker.io/library/debian:12 sleep infinity
  • kubectl exec -it mypod -- bash
  • kubectl delete pod/mypod
  • kubectl config current-context, kubectl config use-context mycontext
  • kubectl --context mycontext -n mynamespace get pod
  • kubectl port-forward pod/mypod '8080:80'
  • kubectl get secret/mysecret -ojsonpath={.data.password} | base64 -d; echo
  • kubectl cordon mynode, kubectl drain --ignore-daemonsets --delete-emptydir-data mynode
  • kubectl rollout restart sts/mysts
  • time kubectl api-resources --verbs=list -oname | xargs -n1 kubectl get -A -owide --show-kind --ignore-not-found
  • helm repo add bitnami https://charts.bitnami.com/bitnami && helm repo update
  • helm --kube-context mycontext -n mynamespace list, helm list -Aa
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kubectl apply -f- << 'EOF'
---
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
    - name: main
      image: docker.io/library/debian:12
      args: [sleep, infinity]
      volumeMounts: [{ mountPath: /v, name: v, readOnly: true }]
  volumes:
    - name: v
      persistentVolumeClaim: { claimName: mypvc, readOnly: true }
EOF

Git Bash (Windows)

  • export MSYS_NO_PATHCONV=1, python -c'import sys;print(sys.argv)' foo bar
  • winpty rclone --config= ncdu .
  • choco list
  • choco install -y gsudo
  • sudo choco upgrade -y all
  • sudo choco install -y winfsp rclone, rclone mount myremote: X: --volname='Volume label' --vfs-disk-space-total-size=2T
  • MSYS=winsymlinks:nativestrict sudo ln -Tsv original.txt link.txt
  • sudo -d mklink link.txt original.txt, sudo -d mklink //d dir-link dir-original
  • [[ "$(uname)" = MINGW* ]]; echo $?
  • MSYS_NO_PATHCONV=1 '/c/Program Files/VeraCrypt/VeraCrypt.exe' /q /v '\Device\Harddisk1\Partition1' /l X /m ro /m label='My label'
  • '/c/Program Files/VeraCrypt/VeraCrypt.exe' //q //v '\Device\Harddisk1\Partition1' //l X //m ro //m label='My label'
  • '/c/Program Files/VeraCrypt/VeraCrypt.exe' //q //d X
  • create-shortcut ~/apps/myapp.exe ~/Desktop/myapp.lnk
  • create-shortcut ~/apps/myapp.exe "$APPDATA/Microsoft/Windows/Start Menu/Programs/Startup/myapp.lnk", sudo create-shortcut ~/apps/myapp.exe '/c/ProgramData/Microsoft/Windows/Start Menu/Programs/Startup/myapp.lnk'
  • cp -vt "$APPDATA/Microsoft/Windows/Start Menu/Programs/Startup" '/c/ProgramData/Microsoft/Windows/Start Menu/Programs/My App.lnk'
  • cygpath -w /d/mymusic/*.mp3 | xargs -rd\\n vlc
  • msg \* MyMessage, date | msg \*
  • reg add 'HKCU\Software\MyApp' //v MyValue //t REG_SZ //d MyData //f, sudo -d reg add 'HKLM\SOFTWARE\MyApp' //v MyValue //t REG_SZ //d MyData //f
  • reg delete 'HKCU\Software\Microsoft\Windows\CurrentVersion\Run' //v MyApp //f, sudo -d reg delete 'HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run' //v MyApp //f

Termux

  • termux-info
  • termux-open myimage.jpg
  • termux-open-url https://example.com/
  • termux-setup-storage

Prometheus queries

  • abs(mymetric - mymetric offset 1m)
  • (mymetric > 0.50) and on() (4*60+20 <= hour()*60+minute() <= 4*60+40)

Python

  • os.chdir(os.path.dirname(os.path.realpath(__file__)))