Reorganize notes

bin/notes

@@ -1,36 +1,33 @@
 #!/usr/bin/env bash
-# Read notes files from ~/.configs_pointer/notes
-if [[ $1 =~ '-h' ]]; then
-  printf 'Open notes files from ~/.configs_pointer/notes\n'
+print_help() {
+  cat <<HELP
+Quickly open notes files from ~/.configs_pointer/notes
+
+No arguments required
+HELP
+}
+
+if [[ -n "$1" ]]; then
+  print_help
   exit 0
 elif ! [[ -h ~/.configs_pointer ]]; then
-  cat <<ERR
-Pointer to configs not found
-Please set up a symlink ~/.config_pointer to the configs directory
-ERR
-  exit 1
-elif ! command -v fzf &>/dev/null; then
-  printf 'Requires fzf\n'
+  printf 'Please set up a symlink ~/.config_pointer to the configs directory\n'
   exit 1
 fi
 
-
-# Fzf for notes file
-if command -v fd &> /dev/null; then
-  notes_file=~/.configs_pointer/notes/"$(fd '.md' ~/.configs_pointer/notes -x basename | fzf)"
-else
-  notes_file="$(find ~/.configs_pointer/notes -type f | fzf)"
-fi
-
+cd ~/.configs_pointer/notes || exit 2
+declare -r notes_file="$(fd -e 'md' | fzf)"
 
 # Use best available pagenator
-if command -v nvim &>/dev/null; then
+if [[ -z "$notes_file" ]]; then
+  printf "No note file selected\n"
+  exit 1
+elif command -v nvim &>/dev/null; then
   nvim -R "${notes_file}"
 elif command -v vim &>/dev/null; then
-  vim -R "${notes_files}"
+  vim -R "${notes_file}"
 elif command -v bat &>/dev/null; then
   bat --paging=always "${notes_file}"
 else
   less "${notes_file}"
 fi
-

notes/futher_intallation/further_installation_macos.md

@@ -0,0 +1,248 @@
+Further recommendations to set your system, after having already run the
+`install.sh` script. A package manager is the cleanest way to install any of the
+apps listed here. Unless specified, these are all open source
+
+# Mac OS
+
+## Shell
+
+Non-graphic open source applications. Use `brew install --formula` unless
+otherwise specified
+
+`pbpaste` except for images. Redirect output to file with `pngpaste - > img.png`
+
+```
+pngpaste
+```
+
+GNU's `coreutils`. Apple has most by default, though they're very outdated
+
+```
+coreutils
+```
+
+File manager for quickly jumping around directories. Not essential
+
+```
+vifm
+```
+
+Quickly search stackoverflow for answers to any query
+
+```
+so
+```
+
+Checks your shell scripts and suggests fixes to potential errors
+
+```
+shellcheck
+```
+
+Non-graphic image manipulator. Very useful in scripts and often a dependency
+
+```
+imagemagick
+```
+
+A much better python REPL and integrates nicely with vim's IPython plugin
+
+```
+ipython
+```
+
+The largest support converting documents types, such as markdown to pdf
+
+```
+pandoc
+```
+
+`ctags` with a lot more language support
+
+```
+universal-ctags
+```
+
+`cut`, `sed`, `grep`, `xargs`, `printf`, etc, for all your stream editing needs
+
+```
+gawk
+```
+
+Foreign filesystems on mac. `sshfs` from `brew install gromgit/fuse/sshfs-mac`
+
+```
+sshfs macfuse
+```
+
+A javascript runtime for servers. It's also useful for shell scripts
+
+```
+node
+```
+
+### Applications
+Applications that should be considered for installation on any mac. Everything
+listed here is open source. Use `brew install --cask` unless otherwise specified
+
+Hotkey daemon for MacOS. Config files can be set up with the install script.
+Either `brew services` or launchd can be used to start `skhd` automatically
+
+```
+skhd ✔️
+```
+
+The most widely used media player capable of decoding almost any format
+
+```
+vlc ✔️
+```
+
+Pairs with `vlc` to watch videos with others remotely
+
+```
+syncplay
+```
+
+Really powerful flashcard memorization software
+
+```
+anki
+```
+
+Pdf reader with contents lists and double display
+
+```
+skim
+```
+
+Installs both a gui version of vim and a more featured non-graphic version too
+
+```
+[nvchad]
+[VapourNvim]
+macvim
+```
+
+Best torrent client. No-nonsense and a nice interface
+
+```
+qbittorrent
+```
+
+Output or capture system-audio by providing a virtual output device
+
+```
+blackhole-2ch
+```
+
+### Power tools
+Heavier applications that should be installed only on capable systems. Use `brew
+install --cask` unless otherwise specified. These are all open source
+
+Full video editor that puts iMovie to shame. Exports require a lot of cpu power
+
+```
+shotcut
+```
+
+Emulator for any operating system. Configuration is complicated. See examples in
+`shell/qemu/`
+
+```
+qemu ✔️
+```
+
+Linux subsystem for mac. Essentially qemu + sshfs automated
+
+```
+lima
+```
+
+Image editing similar to Photoshop, except free and with wider platform support
+
+```
+gimp
+```
+
+Full latex support. Vim configuration and snippets are already setup. Takes
+almost 10G for a base installation and runs hot
+
+```
+mactex ✔️
+```
+
+### Proprietary
+
+Screenshot tool to fill the gap between Mac OS's screenshots and gimp
+
+```
+brew install --cask skitch
+```
+
+Alternative screenshot tool, with a few more markup options
+
+```
+brew install --cask flameshot
+```
+
+
+### Extra nonsense
+
+Make banners for titles
+
+```
+figlet
+```
+
+## Mapping from linux
+
+Macs aren't even close to Linux in virtualisation capabilities, window managers,
+and customizability in general. However, if you're unfortunate enough to find
+yourself with a macbook, all is not lost. Here's a rough porting guide:
+
+| sWayland              | MacOS    |
+| --------------------- | -------- |
+| SwayWM                | [Yabai](https://github.com/koekeishiya/yabai)        |
+| xRemap                | [Karabiner-Elements](https://karabiner-elements.pqrs.org/) |
+| ~/.config/sway/config | [skhd](https://github.com/koekeishiya/skhd)          |
+| swhkd                 | [skhd](https://github.com/koekeishiya/skhd)          |
+| wtype                 | [skhd](https://github.com/koekeishiya/skhd)          |
+| systemd               | Launchd                                              |
+| Zathura               | [Skim](https://skim-app.sourceforge.io/)             |
+| Fuzzel                | [Choose](https://github.com/chipsenkbeil/choose) or Spotlight |
+| udisksctl             | `diskutil`
+| ~/.local/share/fonts  | FontBook                                             |
+| wl-clipboard          | `pbcopy` `pbpaste`                                   |
+| sshd                  | System Preference -> Sharing -> Remote Login         |
+| Super/Ctrl            | Command                                              |
+| Alt                   | Opt                                                  |
+
+For Xorg users, `yabai` is to `skhd` what `bspwm` is to `sxhkd`. Also `launchd`
+is wayyy less capable than `systemd` and rarely gets used. The `launchd` script
+in `./bin` wraps around all the commands you'll ever need
+
+To use open source apps, run `sudo spctl --master-disable`, then head to System
+Preferences -> Security & Privacy -> General and select Anywhere at the bottom.
+You can check it's working with `spctl --status`
+
+While you're here, you can go under Software Updates and uncheck everything
+
+## Window managers
+
+MacOS only allows the default Quartz Compositor, a floating window manager with
+too many animations and almost no keyboard controls. There are two open source
+tiling window managers, which are just scripts overtop Quartz Compositor as
+alternatives. [Amethyst](https://github.com/ianyh/Amethyst) and
+[Yabai](https://github.com/koekeishiya/yabai)
+
+Amethyst provides basic tiling of windows and basic keyboard controls. Yabai is
+effectively a port of bspwm to MacOS and has much more extensive configuration
+than Amethyst, notably controlling workspaces. Unfortunately they don't hold a
+candle to Linux managers. Both can be very laggy and Yabai specifically often
+freezes up for a few seconds, though these are the only options.
+
+To use Yabai, boot into recovery mode, and disable SIP [as explained
+here](https://github.com/koekeishiya/yabai/wiki/Disabling-System-Integrity-Protection).
+Despite what apple says, this doesn't make the system immediately explode.
+Actually there's no difference at all, except being able to use Yabai

notes/futher_intallation/futher_installation_linux.md

@@ -0,0 +1,175 @@
+# Linux
+
+## Fonts
+
+Many scripts assume you have access to [Meslo LGM
+NerdFont](https://github.com/ryanoasis/nerd-fonts/tree/master/patched-fonts/Meslo/M).
+These can be replaced easily with any other nerd font. Other fonts may lack
+support for the right character set
+
+```
+$ mv -i downloaded-fonts/* ~/.local/share/fonts
+# mv -i downloaded-fonts/* /usr/local/share/fonts
+```
+
+See the [ArchWiki](https://wiki.archlinux.org/title/fonts#Manual_installation)
+for more information. TexLive downloads a lot of additional fonts by default too
+
+## xRemap
+
+Remapping keys is done through `xremap`. Despite the name, it works flawlessly
+on Wayland, at least in Sway
+
+Depending on your environment, you need to install a different binary, all of
+which are available through `cargo`. For example `cargo install xremap
+--features sway`. Check [here for more
+options](https://github.com/k0kubun/xremap#installation).
+
+If you're using systemd, run the following:
+
+```
+# ln -s ~/.configs_pointer/xremap/config{_console,}.yml
+# mkdir -p /etc/xremap
+# ln -s {~/.configs_pointer,/etc}/xremap/config.yml
+# cp ~/.configs_pointer/systemd/xremap.service /etc/systemd/system/xremap.service
+# cp ~/.cargo/bin/xremap /usr/local/bin/xremap
+# systemctl enable xremap.service
+# systemctl start xremap.service
+# switch_keyboards.sh pc
+```
+
+You can toggle between Mac-style keyboard and standard keyboard with
+`switch_keyboards.sh` see the doc-comment `vi $(which switch_keyboards.sh)` for
+more information
+
+`sway/config` acts as a hotkey daemon and `wtype` can synthesize input
+
+## Sway
+
+To run sway, install the `sway` and `swaylock` packages. Both configs reference
+`default_wallpaper.png` in their respective directories. Put your wallpaper
+there or change the corresponding `config` file
+
+If sway is acting up, try setting/unsetting `WAYLAND_DISPLAY` and `SWAYSOCK`.
+`swaymsg` also takes an `-s` option which can specify the socket manually
+
+Sway doesn't adjust the gamma on external displays. Compared to MacOS,
+everything looks very washed-out and low contrast. Using `wl-sunset` with `-t
+4000 -T 6500 -g 0.9` brings MacOS-like gamma curves
+
+For more information about sway, read the [i3 User's
+Guide](https://i3wm.org/docs/userguide.html). Particularly chapters 3 and 4 are
+very important for sway
+
+## Multilingual input (fcitx)
+
+IME-style inputs require a complicated setup on wayland. The method described
+here unfortunately scales like Xwayland. That is to say it's very blurry on a
+HiDPI display. Also, IMEs don't work in Alacritty yet. Consider [foot
+terminal](https://codeberg.org/dnkl/foot) if this is important
+
+If you only need an IME in Chromium, [Google Input
+Tools](https://chrome.google.com/webstore/detail/google-input-tools/mclkkofklkfljcocdinagocijmpgbhab)
+is a pretty decent solution. It scales properly on wayland and doesn't require a
+spotty setup. However, it doesn't work in the search bar and makes network calls
+for kanji lookups, which can be really slow
+
+Otherwise you can use fcitx5. Choose a supported IME based on what language you
+need [here](https://wiki.archlinux.org/title/Input_method). For the example
+below we'll install Mozc
+
+```bash
+please pacman -S fcitx5 fcitx5-configtool fcitx5-gtk fcitx5-qt fcitx5-mozc
+please pacman -S gtk4 # For Chromium support
+```
+
+Next add these lines to `/etc/environment`
+
+```
+GTK_IM_MODULE=fcitx
+QT_IM_MODULE=fcitx
+XMODIFIERS=@im=fcitx
+MOZ_ENABLE_WAYLAND=1
+```
+
+Currently, Chromium will only interface with fcitx5 when it's running on the
+non-default gtk4. Add `--gtk-version=4` to `~/.config/chromium-flags.conf`. As
+of writing, this breaks Chromium's built-in file manager, the one for picking
+files. Use Firefox for a better fcitx5 experience
+
+Open fcitx5-configtool to set the required keyboards and change the global
+hotkey. For Mozc, you'd move the Mozc keyboard to the left. Not the other
+Japanese keyboards, those are not IME-based
+
+You may need to reboot wayland or possibly the entire system. Fcitx5 will now be
+available will the following command. Consider adding the following to
+`sway/config` if you want it on startup, or use `<M-i>` to toggle in on/off
+
+```bash
+fcitx5 -d --replace
+```
+
+## AV1 media
+
+AV1 is the hottest new codec on the block, providing compression levels better
+than h265. I've seen it 200x smaller than png, with the same resolution and
+color space
+
+To store images as avif, use `magick convert my_image_name.{png,avif}`. `viu`
+has no support for avif. `imv` supports it out of the box. `vimiv` requires a qt
+plugin for support:
+
+```bash
+please pacman -S libavif
+# Get the latest release from below, for example
+# https://github.com/novomesk/qt-avif-image-plugin/releases/latest
+curl -LO 'https://github.com/novomesk/qt-avif-image-plugin/archive/refs/tags/v0.5.0.tar.gz'
+tar xf qt-avif-image-plugin-0.5.0.tar.gz
+cd qt-avif-image-plugin-0.5.0
+./build_libqavif_dynamic.sh
+please make install
+```
+
+## Chromium
+
+Chromium does not support screen sharing by default on wayland. To add support
+go into `chrome://flags` and enable the "WebRTC PipeWire support" flag. Next
+download the following a reboot to allow screen sharing
+
+```bash
+please pacman -S xdg-desktop-portal-wlr libpipewire02
+```
+
+Consider disabling "Continue running background apps when Chromium is closed" in
+settings
+
+Fix the default fonts in `chrome://settings/fonts`. These are the fallback fonts
+
+For the really daring, change your download location to `/dev/shm`. This is a
+ramdisk which clears all its content on reboot
+
+## Firefox
+
+Firefox will start on xorg by default, unless the `MOZ_ENABLE_WAYLAND=1`
+environment variable is set. Incognito is enabled through the `--private-window`
+flag
+
+Firefox uses `about:config` stored in
+`~/.mozilla/firefox/<random-hash>.default-release/prefs.js`. These are the
+equivalent of Chromium flags. For these configs, simply switch
+`ui.key.menuAccessKeyFocuses` to false, to avoid conflicts with xremap
+
+## Backlights
+
+Laptops usually control the backlight via apci. One program to control this is
+[light](https://github.com/haikarainen/light). By default light requires the use
+of root privileges to modify devices. Use systemd rules and the video group to
+allow unprivileged users to run it normally:
+
+```bash
+curl -LO 'https://raw.githubusercontent.com/haikarainen/light/master/90-backlight.rules'
+please mkdir -p /usr/lib/udev/rules.d
+please cp 90-backlight.rules /usr/lib/udev/rules.d
+# Add your user to the video group
+please usermod -aG video emiliko
+```

notes/linux/aerc.md

@@ -0,0 +1,34 @@
+# Aerc - Allegedly "the world's best email client"
+A terminal email client that's pretty decent out-of-the-box. Configuration is
+divided between 3 files, the most important one is accounts.conf described here
+
+```bash
+please pacman -S aerc w3m dante
+```
+
+You'll need an app password to login. This can be put directly after the email.
+Gmail has one [here for
+example](https://support.google.com/accounts/answer/185833?hl=en)
+
+```
+source   = `imaps://emiliko%40gmail.com:passwordhere123@imap.gmail.com:993`
+```
+
+Or alternatively use the `source-cred-cmd` to retrieve a password through a
+program like `pass`, as shown below
+
+```
+[Gmail]
+source   = `imaps://emiliko%40gmail.com@imap.gmail.com:993`
+source-cred-cmd = `pass show gmail/primary/app_password`
+outgoing = `smtps+plain://emiliko%40gmail.com@smtp.gmail.com:465`
+outgoing-cred-cmd = `pass show gmail/primary/app_password`
+default  = INBOX
+from     = Emiliko Mirror <emiliko@gmail.com>
+copy-to  = Sent
+check-mail = 1m
+```
+
+For other email providers, look up their server names and port, for example
+Fastmail has them [listed
+here](https://www.fastmail.help/hc/en-us/articles/1500000278342)

notes/linux/bluetooth_headphones.md

@@ -0,0 +1,28 @@
+# Airpods - bluetooth audio
+Bluetooth headsets may be unusable with pulse audio by default. Particular
+symptoms include cutting out and compressed playback. This is completely
+independent of the speaker setup, so it won't mess up the config there
+
+Start by finding your bluetooth card's name with
+
+    $ pactl list | grep -Pzo '.*bluez_card(.*\n)*'
+
+This also shows the latency in the output section. It should be 0. Now increase
+the latency. 50000 is a good choice for airpods pro
+
+    $ pactl set-port-latency-offset bluez_card.00_8A_76_4D_9B_BB headphone-output 50000
+    $ systemctl restart bluetooth
+
+That should fix the cutting out issues. Not connect the airpods
+
+    $ bluetoothctl
+    [bt]# power on
+    [bt]# default-agent
+    [bt]# scan on
+      [NEW] Device 00:8A:76:4D:9B:BB Anna’s Airpods
+    [bt]# trust 00:8A:76:4D:9B:BB
+    [bt]# pair 00:8A:76:4D:9B:BB
+    [bt]# connect 00:8A:76:4D:9B:BB
+
+You may need to redirect pulse audio's output to the airpods. Referenced from
+[here](https://askubuntu.com/questions/475987/a2dp-on-pulseaudio-terrible-choppy-skipping-audio)

notes/linux/gnupg.md

@@ -0,0 +1,177 @@
+# GnuPG
+Key files are a secure method for certifying credentials digitally. Everything
+is stored in `~/.gnupg` and controlled through `gpg`. It's quite complicated...
+See `tldr gpg` for encryption, [devhints](https://devhints.io/gnupg) for a
+cheat sheet, the [Archwiki](https://wiki.archlinux.org/title/GnuPG) for a
+technical explanation and the [Debian wiki](https://wiki.debian.org/Subkeys) for
+a newbie-friendly one
+
+Terminology:
+
+ * Public key - The one to share
+ * Private key - The one to not share
+ * Primary key - ??
+ * Subkey - ??
+ * Keygrip - The name of the key file
+ * Key ID - The last few (8-16) characters of a fingerprint
+ * Fingerprint - A unique identifier for a key
+ * Keyring - Your entire collection of public or private keys
+ * User ID - Email, part of name, Key ID, or Fingerprint of a key
+
+Consider this example output:
+```bash
+ $ gpg --list-secret-keys --with-subkey-fingerprint --with-keygrip --keyid-format=long
+
+# ///--- Short for "secret key". It's "pub" for public keys
+# vvv           vvvvvvvvvvvvvvvv Key ID
+> sec   ed25519/ABCDEFG123456789 4040-04-04 [SC] [expires: 4040-04-04]
+>       DDEEDF222222222222222222ABCDEFG123456789
+#                               ^^^^^^^^^^^^^^^^ Key ID also here
+#       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Fingerprint
+>       Keygrip = DDEBBA3482394AEE23432DEE32432BB2432432EE
+# Key is ~/.gnupg/private-keys-v1.d/DDEBBA3482394AEE23432DEE32432BB2432432EE.key
+> uid                 [ultimate] Emiliko Mirror <emiliko@mami2.moe>
+# ///--- Short for "secret subkey". It's "sub" for public subkeys
+# vvv           vvvvvvvvvvvvvvvv Key ID
+> ssb   cv25519/987654321ABCDEED 4040-04-04 [E] [expires: 4040-04-04]
+>       32423BDDAAAAAAAAAAAAAAAA987654321ABCDEED
+#                               ^^^^^^^^^^^^^^^^ Key ID also here
+#       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Fingerprint from --with-subkey-fingerprint
+>       Keygrip = 2493ADDEDDDFEFEFE23432432FDEEFDD24324232
+# Key is ~/.gnupg/private-keys-v1.d/2493ADDEDDDFEFEFE23432432FDEEFDD24324232.key
+```
+
+Providing the `--fingerprint` flag will alter the output slightly, tho it's the
+same fingerprint, for example:
+
+```bash
+> sec   ed25519/ABCDEFG123456789 4040-04-04 [SC] [expires: 4040-04-04]
+>       Key fingerprint = DDEE DF22 2222 2222 2222  2222 ABCD EFG1 2345 6789
+#                                     Key ID is now here ^^^^^^^^^^^^^^^^^^^
+>       Keygrip = DDEBBA3482394AEE23432DEE32432BB2432432EE
+> uid                 [ultimate] Emiliko Mirror <emiliko@mami2.moe>
+> ssb   cv25519/987654321ABCDEED 4040-04-04 [E] [expires: 4040-04-04]
+>       Key fingerprint = 3242 3BDD AAAA AAAA AAAA  AAAA 9876 5432 1ABC DEED
+#                                     Key ID is now here ^^^^^^^^^^^^^^^^^^^
+>       Keygrip = 2493ADDEDDDFEFEFE23432432FDEEFDD24324232
+```
+
+## Creating a new key
+This closely follows the Archwiki, with an elliptic cipher
+
+```
+gpg --full-gen-key --expert
+ > (9) ECC and ECC
+ > (1) Curve 25519
+ > 1y  # Optional, 1 year is recommended
+ > Your Name          # This will be visible in the public key
+ > emiliko@mami2.moe  # This is also visible in the public key
+ > No comment
+ > Put a password on the primary key
+```
+
+## Signing and verification
+Git commits, binaries and really any file can be signed by a private key to
+prove authenticity of the file. For github, you'll need to paste your public key
+to your profile settings
+
+```bash
+gpg --list-secret-keys --keyid-format=long
+gpg --armor --export <user-id> | wl-copy
+```
+
+Git commits aren't signed by default. Either explicitly sign at commit time,
+with `git commit -S`, or add the following to your ~/.gitconfig. If the signing
+key you specify is a subkey, add an ! mark at the end
+
+```toml
+[user]
+name = Emiliko Mirror
+email = emiliko@mami2.moe
+signingkey = ABCDEF1234567890
+[commit]
+gpgsign = true
+```
+
+## Encryption
+Gpg can encrypt pretty much anything. Consider bundling into a tarball
+beforehand if it's more than one file
+
+The `-a/--armor` flag will make sure the encrypted file is made up entirely of
+ascii characters, which is easier to copy/paste than binary nonsense
+
+Encryption can be symmetric or asymmetric. Symmetric encryption uses 1 key and a
+password to encrypt. To decrypt, use the same key and re-enter the same
+password
+
+### Symmetric encryption
+Symmetric encryption uses 1 key and 1 password to encrypt. To decrypt, you'll
+need the same key and the same password
+
+### Asymmetric encryption
+Asymmetric encryption is meant for sending to a specific receiver. It uses 1
+public key to encrypt. To decrypt, you'll need the private key pair to that
+public key. `pass` uses this one
+
+```bash
+gpg -e -o encrypted_file -r emiliko@mami2.moe secret_file
+# Then emiliko can decrypt it with her private key
+gpg -d -o secret_file encrypted_file
+```
+
+## Moving keys
+You'll want to export your keys to other devices. Ideally, you'd only export
+subkeys and not the primary key. The primary key should be stored offline and
+used to generate revocation certificates for compromised subkeys
+
+```bash
+gpg -o pub_key.pgp -a --export emiliko@mami2.moe
+gpg -o sec_key.pgp -a --export-secret-key emiliko@mami2.moe
+
+scp pub_key.gpg emiliko@192.168.0.1:/tmp/safe_directory
+scp sec_key.gpg emiliko@192.168.0.1:/tmp/safe_directory
+
+gpg --import pub_key.gpg
+gpg --import sec_key.gpg
+
+```
+A safer method skips the creation of any intermediary files by sending it
+through ssh right away
+
+```bash
+gpg --export-secret-key <user-id> | ssh emiliko@192.168.0.1 'gpg --import'
+# Or if you're on the receiving system
+ssh emiliko@192.168.0.1 'gpg --export-secret-key emiliko@mami2.moe' | gpg --import
+```
+
+In either case, or actually whenever importing your keys, you'll need to edit
+the trust level after importing it
+
+```bash
+gpg --list-keys  # Get the Key ID here
+gpg --edit-key <user-id>
+> trust
+> 5 # If it's your own key
+> y
+> quit
+```
+
+For use with `pass`, you can check if your encryption key is working by trying
+to add a new password, like `pass insert -e something` and see if it succeeds
+
+## Backing up keys
+Keys should be backed up on offline, physically inaccessible, media. Usb sticks
+you leave at home or a piece of paper are both good choices. For the paper
+version see `paperkey`
+
+```bash
+gpg -o /run/media/my_usb/keys.gpg --export-options backup --export-secret-keys emiliko@mami2.moe
+```
+
+Now later, or on another device, you can restore these keys
+
+```bash
+gpg --import-options restore --import keys.gpg
+```
+
+Then edit the trust level, as with the other transfer methods

notes/linux/linux_networks.md

@@ -0,0 +1,220 @@
+# Networks
+This file covers wifi and bluetooth connections on linux
+
+Required packages for the guide:
+ - systemd
+ - NetworkManager
+ - `bluetoothctl`
+
+Optional GUI tools to make this easier:
+ - `pacman -S nm-connection-editor`
+ - `pacman -S blueberry`
+
+# Basic networks
+For Archlinux, choose between NetworkManager and netctl for your networking
+needs. NetworkManager comes from the GNOME project and is fully feature packed
+from the getgo. Netctl is a set of light shell scripts that rely on external
+packages for networking, so a bit harder to install
+
+Both can be checked with systemd
+```bash
+systemctl status netctl.service
+systemctl status NetworkManager.service
+```
+
+**Make sure only one is running and enabled**. Using both at the same time will
+result in system slowdowns, especially at boot times
+
+## NetworkManager and netctl conflict
+If your system is running some `/sys/.../subnet...` for 90s at startup, likely
+netctl is trying to start up a device, though the device name has changed.
+Places to check:
+
+    /etc/NetworkManager/system-connections/
+    cd /etc/systemd/system/multi-user.target.wants/ && rg enp0s3
+    vi /etc/systemd/system/multi-user.target.wants/netctl@enp4s0.service
+    vi netctl@enp4s0.service
+
+If you are using both by accident, make sure to use the native disable in
+addition to the systemd disable. For example, with netctl:
+
+    systemctl disable netctl
+    systemctl disable netctl@enp4s0.service
+    netctl disable enp4s0
+
+## Public networks
+Public networks often use a captive portal to make users accept their terms and
+conditions
+
+ 1. Connect to the network using `nmtui` or similar
+ 2. Use a GUI browser and navigate to any site
+ 3. If that doesn't work, try navigating to a non-https using page
+ 4. If that doesn't work, try navigating to a site you've never visited in incognito
+ 5. If that doesn't work, try navigating to the router at 192.168.[0-1].[0-1]
+
+# Bluetooth
+Before starting bluetooth, make sure bluetooth.service is running, otherwise
+nothing will work
+
+```bash
+systemctl start bluetooth.service
+```
+
+You may optionally install the `blueberry` GUI package. It's quite light and
+limited, though it's a good way to check if your devices are connected
+
+## Keyboard
+Start `bluetoothctl`. The command sequence to connect will look something like:
+
+    $ bluetoothctl
+    [bluetooth]# power on
+    [bluetooth]# agent off
+    [bluetooth]# agent KeyboardOnly
+    [bluetooth]# scan on
+    [bluetooth]# pair <MAC-ADDR>
+    [bluetooth]# trust <MAC-ADDR>
+    [bluetooth]# connect <MAC-ADDR>
+    [bluetooth]# quit
+
+When you turn `scan on`, the list may explode with various mac addresses. Try to
+find your keyboard amongst those. During the `pair` section, `bluetoothctl` may
+prompt you with 6 digits. Type those on the keyboard and possibly hit enter
+after them
+
+See the [Archwiki page](https://wiki.archlinux.org/title/bluetooth_keyboard) for
+more info
+
+## Bluetooth headphones
+This section connected AirPods Pro. Setup may differ for other devices
+
+Start by connecting your headphones with a very similar set of steps as the
+keyboard guide above. Use `default-agent` instead of `agent KeyboardOnly`. For
+example:
+
+    $ bluetoothctl
+    [bt]# power on
+    [bt]# default-agent
+    [bt]# scan on
+      [NEW] Device 00:8A:76:4D:9B:BB Anna’s Airpods
+    [bt]# trust 00:8A:76:4D:9B:BB
+    [bt]# pair 00:8A:76:4D:9B:BB
+    [bt]# connect 00:8A:76:4D:9B:BB
+
+Once connected, blue headphones may cutout or just not play back anything. This
+is a PulseAudio issue. The bluetooth sound latency may need to be adjusted
+
+Start by finding your bluetooth card's name with
+
+    $ pactl list | grep -Pzo '.*bluez_card(.*\n)*'
+
+Next increase the audio latency. 50000ms seems to work well for AirPods Pro,
+though this is likely [different for other
+headphones](https://askubuntu.com/questions/475987/a2dp-on-pulseaudio-terrible-choppy-skipping-audio)
+
+    $ pactl set-port-latency-offset bluez_card.00_8A_76_4D_9B_BB headphone-output 50000
+    $ systemctl restart bluetooth.service
+
+Repeat the steps above, adjusting the bluetooth sound latency, until it works.
+Consider using the `blueberry` GUI to quickly reconnect the headphones on each
+bluetooth.service restart. Don't forget to relaunch `blueberry` every time too
+
+```bash
+kill $(pgrep ^blueberry$) && systemctl restart bluetooth.service && blueberry &
+```
+
+# Enterprise networks
+Large organizations, like universities, use enterprise security on their
+networks. These require an account to login, not just a password
+
+The guide below assumes the network's name is "UWS" and your login username is
+"emiliko"
+
+You can install the optional `nm-connection-editor` to make things easier
+
+    $ nmcli device wifi list
+This should show the network you're looking for
+
+If your network is not using PAP authentication, it may be possible to just
+connect with a simple password, try:
+
+```bash
+nmcli --ask device wifi connect UWS
+```
+
+Otherwise run this line, replacing the necessary information in the line above.
+Particularly `UWS`, `emiliko` and `wlan0`. For `wlan0`, find your wifi device
+with `ip link`. `enp...` is usually ethernet
+
+```bash
+nmcli connection add type wifi con-name "UWS" ifname wlan0 ssid "UWS" -- wifi-sec.key-mgmt wpa-eap 802-1x.eap ttls 802-1x.phase2-auth mschapv2 802-1x.identity "emiliko"
+```
+
+## Option 1: With nm-connection-editor
+Open `nm-connection-editor`. Go into "Wifi-Security" and make it look like:
+
+    WPA & WPA2 Enterprise
+    Tunnled TLS
+    CA Certificate: (None)
+    Check No CA certificate required
+    Inner authentication: PAP
+Type in your login credentials at the bottom. Now run
+
+## Option 2: Without nm-connection-editor
+If you don't have the GUI tool `nm-connection-editor` and no way to install it,
+you can try editing the network's profile directly. The relevant file is at
+`/etc/NetworkManager/system-connections/UWS.nmconnection`
+
+This file should look something like below, with relevant information replaced.
+The file can only be accessed by root
+
+```
+[connection]
+id=UWS
+uuid=cb62f680-e1da-41c9-bfa0-35e7ef6f5137
+type=wifi
+interface-name=wlan0
+timestamp=1657043376
+
+[wifi]
+mode=infrastructure
+ssid=UWS
+
+[wifi-security]
+key-mgmt=wpa-eap
+
+[802-1x]
+eap=ttls;
+identity=emiliko
+password=PutYourPasswordInPlainTextHere_YesPlainText
+phase2-auth=pap
+
+[ipv4]
+method=auto
+
+[ipv6]
+addr-gen-mode=stable-privacy
+method=auto
+
+[proxy]
+```
+
+Alternatively, use the file above as a reference to edit it via
+
+```bash
+nmcli connection edit UWS
+```
+
+## After setting up above
+```bash
+nmcli device wifi connect UWS
+```
+
+NetworkManager takes a bit, about 30s, to finish authentication. This will also
+happen during boot, so you can't use the network right away
+
+If your network does not use PAP authetication, it might just work to type the
+password in
+
+```bash
+nmcli --ask device wifi connect UWS
+```

notes/linux/pass.md

@@ -0,0 +1,19 @@
+# Pass - The Unix password manager
+Forget proprietary password managers that require a subscription, use `pass` to
+generate, store, and retrieve all your passwords through your gpg key
+
+```bash
+pass init emiliko@mami2.moe
+pass insert university/password
+pass insert -e university/username
+```
+
+Passwords, or rather entire files can be retrieved to stdout, the clipboard, or
+a qrcode. Stdout will show multiline files. `-c` will only copy the first line
+to `wl-clipboard` for `PASSWORD_STORE_CLIP_TIME` or 45s
+
+```bash
+pass [show] university/password
+pass [show] -c university/password
+pass [show] -q university/password
+```

notes/linux/ramdisks.md

@@ -0,0 +1,26 @@
+# Ramdisks
+Ram is fast and files sometimes need to be quick. Disks via ramfs and tmpfs
+allow us to mount a file system entirely in the ram, and it's supported by the
+linux kernel out of the box
+
+Tmpfs is the newer version of ramfs, with the only difference being that tmpfs
+has a maximum size that it won't exceed. Ramfs doesn't actually bound its own
+size, so the system can run out of memory
+
+    # mount -t tmpfs -o uid=1000,size=1g tmpfs /home/emiliko/mnt
+
+Mounts a temporary file system with a maximum size of 1GB at ~/mnt. Ramdisks
+only use the size they need, so mounting this blank file system won't take up
+any ram at first
+
+Unmounting a ramdisk will clear everything off, which happens every time the
+system is powered off
+
+Linux systems come with a `/dev/shm` directory by default, which is a ramdisk
+accessible by all users. To find the size of a ramdisk use `df -h /dev/shm`. To
+check which ramdisks are mounted, use `findmnt` or `mount`
+
+For more information:
+ - `man 8 mount`
+ - `man 5 tmpfs`
+ - [ArchWiki](https://wiki.archlinux.org/title/tmpfs)

notes/linux/usb_mounting_disks.md

@@ -0,0 +1,50 @@
+# Mounting disks
+On MacOS, there's `diskutil` which handles everything to do with disks and
+partitioning all in one. It also has a graphical frontend. Macs by default
+automatically mount readable external media into `/Volumes` and nothing explicit
+needs to be done, although `diskutil` can trigger this as well
+
+In Linux, the functionality of this tool is broken up into `fdisk`, `lsblk`,
+`df`, `parted`, and `mount`. For querying information, these overlap heavily and
+can often be used interchangeably. `lsblk` is often sufficient to query external
+drives, with the following options:
+
+```bash
+lsblkf -o name,label,fstype,mountpoint,size,state
+```
+
+However, `mount` is a particularly bad substitute for `diskutil`. For one it
+needs root privileges for something as simple as mounting a usb stick. It also
+doesn't create mount pointer for us in `/Volumes`, we have do to that manually
+
+Instead, it's a good idea to install `udisks2`. "Easier" distros typically come
+with this or something similar preinstalled. `udisksctl` is much more similar to
+`diskutil`. It'll mount drives without requiring root into
+`/run/media/<username>/`, using the EFI label for that partition
+
+```bash
+udisksctl help
+udisksctl mount -b /dev/sda2
+udisksctl mount -b /dev/sda3
+```
+
+You can mount multiple partitions from the same block device at the same time
+
+Do not try to mix `mount` and `udisksctl`! This can lead to some severe
+nonsense, like ghost disks. Before using `udisksctl` consider checking the
+output of `mount`. Note that `lsblk` may know less than `mount` and `df`
+
+There are no guarantees that an external drive will have any particular name.
+This is problematic in scripts and requires an `lsblk` every time before
+mounting external media. Instead you can use the automatically created symlink
+in `/dev/disk/by-*`. For example, a partition with label `hey_hey` can always be
+mounted with
+
+```bash
+udisksctl mount -b /dev/disk/by-label/hey_hey
+```
+
+There can presumably be problems with conflicting partition labels, though it's
+better not to use `udisksctl` in that case either. `/dev/disk/by-id/*` uses WWID
+for identification, which is stored on the hardware for the drive and guaranteed
+to be universally unique. That's a better idea for the fstab file

notes/linux/veracrypt.md

@@ -0,0 +1,46 @@
+# Veracrypt
+A cross-platform block device encryption program with support for passwords,
+keys, hidden volumes, and manual PIM setting for security
+
+Here we use `alias vera='veracrypt -t'` for the non-graphic interface
+
+AES is the best all-round choice of cipher. Sha256 is the best choice of hash
+
+Keyfiles must be prepared before locking a volume. `vera --create-keyfile` can
+create one, or just use a few 100 bytes from /dev/urandom in a file.
+
+Veracrypt devices must be mounted on a directory and require root access to use
+`mount`
+
+Dismount volumes with the `-d` option, providing a path to the mount point, the
+name of the volume, or nothing to unmount all veracrypt volumes. Sometimes
+veracrypt may fail to unmount. To check which process is using the container use
+
+```bash
+please fuser -vm <mount-point>
+# For the really desperate
+lsof
+# Or if it must be closed no matter what process is using it
+vera --force --dismount
+umount -f <mount-point>
+```
+
+## Creating a new volume interactively
+Start with `vera -c`. The most sensible default are:
+
+```
+Volume type: Normal
+Volume path: /home/emiliko/file_name  # Use absolute path!
+Volume size?
+Encryption Algorithm: (1) AES
+Hash algorithm: (1) SHA-512
+Filesystem: (8) Btrfs
+```
+
+## iNode problems
+If you're making a very small container, you may run into inode issues. Btrfs
+doesn't use inodes, so it should be ideal. However, btrfs requires a file system
+over 1M for sure
+
+Ext4 uses inodes and by default won't have nearly enough on a small drive. For
+example, the default is 96 inodes for a 1M drive

notes/macos/apple_bsd.md

@@ -0,0 +1,128 @@
+# Apple corner
+MacOS is a BSD derivative that constantly does things differently under the
+hood. While most things are Unix compatible, some things are just different
+
+### Basic setup
+MacOS requires a few manual interventions to get the system working
+
+    # spctl --master-disable
+Reveals the option in "Security & Privacy" to run apps from any developer
+
+    ~/Library/Sounds/madoka_error.aiff
+Sound files stored in this directory are available under Sound -> Sound Effects
+
+    ~/Library/KeyBindings/DefaultKeyBinding.dict
+Allows basic remapping for system-wide key binds. Use `skhd` for complex hotkeys
+
+### Basic commands
+
+    $ echo 'hello' | pbcopy
+    $ pbpaste > note.txt
+Interact with the system clipboard through terminal. This does not work for
+images. Install `pngpaste` for that functionality
+
+    $ say 'something'
+Says string with system voice. Useful as a notification for when a task is done
+
+    $ afplay
+Plays the audio of an audio file, such as an `mp3` or `wav`
+
+### Disk Utility
+
+    $ diskutil list
+Lists all the volumes the system currently sees. This works for unmounted and
+encrypted partitions as well
+
+    $ diskutil mount disk1s1
+Mounts `disk1s1`. Most useful to mount USB drives without physically reseeding
+
+    $ diskutil apfs unlockVolume disk1s1
+Unlocks and mounts an apple file system volume
+
+### Launch daemon
+Systemd for MacOS. It will automatically load scripts in designated directories
+on login. It can also be controlled manually through `launchctl`
+
+    $ launchctl load -w ~/Library/LaunchAgents/com.skhd.plist
+    $ launchctl unload -w ~/Library/LaunchAgents/com.skhd.plist
+Loads and starts the skhd daemon. `<key>Label</key>` must be the same to unload
+
+    # launchctl list | grep skhd
+Check the status of a running process. First number is the PID, second number is
+the exit code. If the second number isn't 0 or there's no PID something broke
+
+    /Users/emiliko/Library/LaunchAgents/com.launcher.plist
+This file will be started automatically on emiliko's login. All paths provided
+in must be absolute paths from root. Use `/Users/emiliko/` not `~/`
+
+    /Users/emiliko/Library/LaunchAgents/com.launcher.plist
+    <key>StandardOutPath</key>
+    <string>/tmp/skhd.out</string>
+    <key>StandardErrorPath</key>
+    <string>/tmp/skhd.err</string>
+Redirects stdout and stderr. Watch these files with `tail -f /tmp/skhd.err | nl`
+
+### Installing SSHFS on Mac
+To set up ssh filesystem (sshfs) on a mac, follow these steps on the client:
+
+    $ brew install --cask osxfuse
+Installs `osxfuse`. This is an open source tool to extend your mac's fs support
+
+    https://osxfuse.github.io/
+    $ curl https://github.com/osxfuse/sshfs/releases/download/osxfuse-sshfs-2.5.0/sshfs-2.5.0.pkg
+Recently brew removed sshfs from its supported casks, since it relies on closed
+source code. Instead, you'll need to install it directly from the download link
+
+See ssh_notes for using SSHFS
+
+### OSA script
+MacOS's GUI can often be controlled through the use of Apple's `osascript`.
+Notably, this can allow shell programs to give GUI notifications
+
+    osascript -e 'display notification "'"${message}"'
+Sends the system notification with the contents of `$message`
+
+    osascript -e 'display notification "'"${msg}"'" with title "Skhd"'
+Adds a "Skhd" as a title to the notification
+
+    osascript -e 'display notification "'"${msg}"'" with title "Skhd" subtitle
+    "Could not save image"'
+Further adds a subtitle for the notification
+
+    afplay $(defaults read .GlobalPreferences.plist \
+        | awk '/sound.beep.sound"/ { gsub(/(.*= ")|(";)/, "", $0); print }')
+Plays the default system error sound through the current audio output device
+
+
+## FreeBSD corner
+Keep in mind that MacOS is based on a really old FreeBSD and NetBSD kernel, so
+many sections here will somewhat apply to Macs as well
+
+#### Users and groups
+Various commands for managing system permissions. Many can be, at least
+somewhat, run the user themselves with their password
+
+    # adduser
+    # rmuser
+    $ chpass  # edit user account settings, like login name and expiry
+    $ passwd  # change a user's password
+    $ pw      # a cli frontend for the settings files above. More advanced
+https://docs.freebsd.org/en/books/handbook/basics/#users-modifying
+
+    /etc/group
+    $ id emiliko
+Shows groups a user belongs to. User seems to implicitly belong to their group
+
+    rwxr-x---x  .
+    rwxr-x-r--  secret_file
+    rwxr-x-rw-  no_touching
+Oddly, the `x` on the directory here means means all other users:
+ - Can `cd` into the directory
+ - Cannot `ls` in this directory
+ - Can read the file `secret_file` using something like `vim secret_file`
+ - Can write to `no_touching`. Vim can only do this with `:x!` not `:w!`
+
+    # service sshd restart
+Reboots the ssh daemon. Users connected through ssh won't lose connection, if
+the reboot is successful
+[//]: # ex: set ft=markdown:tw=80:

notes/macos/macos_groups.md

@@ -0,0 +1,21 @@
+# Groups in macos
+
+```bash
+sudo dscl . -create /groups/newgroupname
+sudo dscl . -append /groups/newgroupname gid 4200
+```
+
+Creates a new group. Alternatively use System Preferences -> Users and Groups
+
+```bash
+id -Gn emiliko
+```
+
+List all the groups `emiliko` belongs to
+
+```bash
+sudo chmod -R g=u .
+```
+
+Set the group privileges of the file hierarchy rooted at `.` to be the same as
+the user. Very nice to convert a directory to be editable by ssh users

notes/macos/macos_qemu.md

@@ -0,0 +1,37 @@
+# Qemu
+Optimized options that seem to work on MacOS:
+
+```bash
+-m 4G -smp 6                # Resources: Use 4GB memory and 6 cpus
+-machine type=q35,accel=hvf # Machine: Default is `pc`. `q35` should be better. Haven't noticed any perfomance gains
+                            # Hypervisor: Uses HyperVisorFramework to speed up qemu a LOT, ~6x
+-drive file=archlinux.qcow2,media=disk,if=virtio  # Boot: Points to the image
+-nic user,hostfwd=tcp::10022-:22  # Network: Forward host port 10022 to guest 22, so `ssh -p10022 user@localhost` should work
+
+# Display options on MacOS:
+    # If you launch this script in the background, the same terminal can be
+    # used to ssh into qemu. After exiting, tmux's scrollback breaks. Opening
+    # and closing [n]vim fixes this...
+-nographic
+    # Doesn't do anything noticably different from just -nographic
+-monitor none -curses -nographic
+    # Support a 4k instance on MacOS. A spice server would be better. It's
+    # really laggy with KDE, to the point of unusable
+-vga virtio -full-screen -display cocoa
+    # Only supports 1080p. MacOS must use a cocoa display. Compared to above
+    # the display scales by 2x which makes text bigger tho more blurry
+-vga std -display cocoa
+```
+
+# Qemu fully nongraphic
+
+MacOS can't use `-display ncurses` properly with qemu. Ncurses requires a linux
+kernel to work properly. Instead use `-nographic` and launch the process in the
+background. Bash uses `&` for backgrounding. You can now SSH into the qemu
+instance.
+
+Bonus:
+For shared file systems, there are two options on Macs:
+ - MacFUSE - Manually setup and mount with sshfs. It's much easier to use
+ - lima - Tries to do reverse sshfs for you and forwards ports too. This one is
+   pretty new and questionably useful compared to manually using sshfs

notes/python/ipython_np.md

@@ -0,0 +1,37 @@
+Notes python and IPython
+
+## Python
+#### Virtual envs
+Virtual environments are the `chroot` and `jails` of python. They essentially
+temporarily append to the path and source locally installed versions of packages
+
+    $ python3 -m venv jail
+Creates a new python in
+
+    $ source jail/bin/activate
+    $ deactivate
+Start and stop the venv. The `$PS1` should indicate which one is active
+
+    $ pip install numpy ipython
+Installs latest versions of packages to the venv. Use `pip` not `pip3` in venvs
+
+## IPython
+For a full blown IDE experience in shell, you'll want to use the IPython REPL.
+Follow the vim ipython setup instructions to use it rStudio style
+
+#### Magic in scripts
+    >>> from IPython import get_ipython
+    >>> get_ipython().magic('reset -f')
+Functions exactly like typing `%reset -f` in the IPython interpreter. When
+sourcing entire files, percent magic syntax won't work
+
+#### Graphical interface
+For certain applications, such as plotting graphs, a gui becomes much more
+capable than a terminal. `matplotlib` can be easily set up to open a
+live-updating gui window controlled by `ipython`
+
+    >>> get_ipython.magic('pylab')
+    In [01]: %pylab
+Starts up a gui for plots. It may not open until the first figure is created
+
+[//]: # ex: set ft=markdown tw=80:

notes/python/jupyter.md

@@ -0,0 +1,64 @@
+# Jupyter
+Despite being one of the most prolific modern languages, python suffers from a
+dangerous amount of not-invented-here syndrome. Prepare to fight on all fronts
+while python reinvents the wheels, though makes it square, just since a
+text-based terminal is too intimidating for new cs students
+
+Firstly you'll want to install python and all the other required packages:
+
+```
+# pacman -S python python-pip
+# pacman -S jupyter_console python-qtconsole python-ipython-genutils
+# pacman -S python-pynvim  # For neovim only
+```
+
+Next you'll want to generate the configs required for Vim to connect with
+Jupyter. Follow this section of the
+[readme](https://github.com/jupyter-vim/jupyter-vim#jupyter-configuration).
+Jupyter does not come with manpages, though it does give useful support by using
+`-h` for any of its subcommands
+
+Now we need to make a virtual environment, otherwise pip will pollute package
+dependencies all over the system. Create a new environment directory:
+
+```
+$ python3 -m venv new_env_dir
+$ cd new_env_dir
+$ . bin/activate
+```
+
+Now you can install packages with pip, so long as the prompt stays "activated".
+If you aren't sure, open another pane and reactivate from there
+
+```
+$ python -m pip install ipykernel
+$ python -m pip install numpy matplotlib networkx
+```
+
+Trying to use Jupyter now still won't work. Since virtual environments are very
+thin layer that just modifies some environment variables, Jupyter will still run
+as if it's being run from a normal shell. We'll need to attach this venv as a
+separate kernel on the system Jupyter installation. For example:
+
+```
+$ python3 -m ipykernel install --user --name=my_kernel_name
+```
+
+Now Jupyter should see it. You can use any shell from here on, not just the
+venv-activated one
+
+```
+$ jupyter kernelspec list
+```
+
+We can connect to this kernel with an option
+
+```
+$ jupyter console --kernel=my_kernel_name
+```
+
+Removing the kernel later is easy too
+
+```
+$ jupyter kernelspec remove my_kernel_name
+```

notes/python/vim_ipython_repl.md

@@ -0,0 +1,33 @@
+# REPL interaction
+
+Vim can take advantage of read evaluate print loops (REPL) to run code 'cells'.
+This is similar to the experience in Jupyter notebooks, Colab, and RStudio
+
+# IPython
+
+This is for the IPython interpreter. The normal python REPL isn't as easy to use
+
+```vim
+Plug 'jpalardy/vim-slime'
+```
+
+Necessary for any sort of REPL interaction through vim. Lets vim send text to
+other terminals or tmux panes
+
+```vim
+Plug 'hanschen/vim-ipython-cell'
+```
+
+Plugin provides many conveniences for interacting with REPLs, such as one-line
+execution, highlighted cell delimiters, and navigation between cells
+
+# Julia
+
+Use the same setup as the IPython REPL, except modify the evaluation string
+
+```vim
+let g:ipython_cell_run_command = 'Base.run(`clear`); include("{filepath}")'
+let g:ipython_cell_cell_command = 'include_string(Main, clipboard())'
+```
+
+Julia equivalents for pasting the clipboard and executing a file

notes/qemu/installation_qemu.sh

@@ -0,0 +1,8 @@
+qemu-system-x86_64 \
+	-m 4G \
+	-boot d \
+	-display cocoa \
+	-machine type=q35,accel=hvf \
+	-smp 2 \
+	-drive file=archlinux-2021.01.01.qcow2,media=disk,if=virtio \
+	-cdrom /Users/emiliko/documents/safe/arch_vm/archlinux-2021.01.01-x86_64.iso

notes/qemu/qemu_arch_start.sh

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+# Qemu booting on MacOS
+qemu-system-x86_64 \
+    -m 4G -smp 6 \
+    -nographic \
+    -accel hvf \
+    -drive file=archlinux-2021.01.01.qcow2,media=disk,if=virtio \
+    -nic user,hostfwd=tcp::10022-:22 &> /dev/null
+
+exit 0
+# Above invocation explained
+-m 4G -smp 6                # Resources: Use 4GB memory and 6 cpus
+-machine type=q35,accel=hvf # Machine: Default is `pc`. `q35` should be better, tho haven't noticed anything
+                            # Hypervisor: Uses HyperVisorFramework to speed up qemu a LOT, ~6x
+-drive file=archlinux.qcow2,media=disk,if=virtio  # Boot: Points to the image
+-nic user,hostfwd=tcp::10022-:22  # Network: Forward host port 10022 to guest 22, so `ssh -p10022 user@localhost` should work
+
+
+# Display options:
+    # If you launch this script in the background, the same terminal can be
+    # used to ssh into qemu. After exiting, tmux's scrollback breaks. Opening
+    # and closing [n]vim fixes this...
+-nographic \
+    # Doesn't do anything noticably different from just -nographic
+-monitor none -curses -nographic \
+    # Support a 4k instance on MacOS. A spice server would be better. It's
+    # really laggy with KDE, to the point of unusable
+-vga virtio -full-screen -display cocoa \
+    # Only supports 1080p. MacOS must use a cocoa display. Compared to above
+    # the display scales by 2x which makes text bigger tho more blurry
+-vga std -display cocoa \
+
+
+# Previously used presets:
+-monitor none \
+-vga virtio -full-screen -display cocoa \  # 4k supported, though it's really slow at 4k
+-vga std \ # Normal run, only supports up to 1080p
+-accel hvf \
+# possible
+-vga virto \
+-enable-kvm \
+#
+-net tap,script=/Users/emiliko/documents/safe/arch_vm/tap-up,downscript=/Users/emiliko/documents/safe/arch_vm/tap-down
+    -nographic \
+    -chardev stdio,id=char0 \
+    -serial chardev:char0 \
+    -monitor none \
+    -net nic,model=virtio,macaddr=54:54:00:55:55:55 \
+
+

notes/qemu/qemu_start.sh

@@ -0,0 +1,14 @@
+qemu-system-x86_64 \
+	-m 4G \
+	-smp 6 \
+	-boot d \
+	-display cocoa \
+	-vga std \
+	-serial stdio \
+	-machine type=q35,accel=hvf \
+	-drive file=archlinux-2021.01.01.qcow2,media=disk,if=virtio \
+	-nic user,hostfwd=tcp::10022-:22
+    #-net tap,script=/Users/emiliko/documents/safe/arch_vm/tap-up,downscript=/Users/emiliko/documents/safe/arch_vm/tap-down
+    #-net nic,model=virtio,macaddr=54:54:00:55:55:55 \
+
+

notes/shell/chrontab.md

@@ -0,0 +1,27 @@
+# Crontab
+Run programs at a given time. Useful for system cleanups and updates
+
+```bash
+crontab -e
+```
+
+Edit your crontab file
+
+Syntax looks like (min, hour, day, month, year). Note these are absolute values,
+so putting something like `* 1 * * *` will run the program at `1:00am` every
+day. To understand these times use [this](https://crontab.guru/) Example crontab
+file:
+
+```bash
+PATH=/usr/local/bin:/bin:/usr/bin
+HOME=/home/emiliko
+
+* * * * * ~/program_1.sh  # Every minute, on the minute
+* * * * * (sleep 30; ~/program_1.sh)  # Every minute at 30s in
+1 * * * * ~/program_2.sh   # Every hour at :01 minute
+1 * 3 * * ~/program_3.sh   # Every day at 3:01am
+```
+
+Since crontab doesn't support resolutions greater than 1 minute, a workaround
+with `sleep` can be used instead. `program_1.sh` above effectively runs every
+30s

notes/shell/ffmpeg_subtitle_extraction.md

@@ -0,0 +1,19 @@
+# Extract subtitles with ffmpeg
+
+```
+ffmpeg -i Movie.mkv -map 0:s:0 subs.srt
+```
+
+Extract subtitles from the mkv file. This one extracts the 0th subtitle track.
+To extract the first, use `-map 0:s:1`
+
+```
+ffmpeg -ss 10 -t 10 Movie.mkv audio.mp3
+```
+
+Another curious thing is [ffmpeg's treatment of arguments](ffmpeg relative). All arguments that
+come before a file are applied to that file only. The remainder of the command
+is relative to those inital args. This means seeking forward 10s then cutting
+10s will actually cut out the 10-20s interval
+
+[ffmpeg relative]: https://stackoverflow.com/questions/46508055/using-ffmpeg-to-cut-audio-from-to-position

notes/shell/fifo.md

@@ -0,0 +1,52 @@
+# Shell pipes and fifo
+Most bash "blocks" accept a redirection parameter at the end of their
+declaration. This can replace where the output and errors are going
+
+```bash
+fn () {
+  echo "error" >&3
+} 3>&2 2>file
+# Prints "error" to the standard error. The real stderr is stored in ./file
+```
+
+ - Functions, as above
+ - Sub-shells: `(echo "one"; echo "two") > file`
+ - Loops: `while (1); do echo "loop"; done > file`
+
+Remember that redirection syntax looks like `[fd][< | >][&fd | file_path]`,
+where `fd` is the index in the process' file descriptors. This works for `<` as
+well. `|&` is identical to using `2>&1 |`
+
+The order of IO redirection matters. Redirection will go to wherever the
+redirected destination currently goes. Redeclaring a redirection doesn't work
+
+```
+            ┌3 writes to stdout
+            │    ┌stdout writes to stderr
+            │    │    ┌stderr writes to where 3 writes, so stdout
+            │    │    │
+echo "one" 3>&1 1>&2 2>&3
+```
+
+To do this for the entire shell or script, use `exec`
+
+```bash
+exec 4>&1          # Holds onto reference to stdout
+exec 1>/dev/null   # Silences stdout and loses track of it
+exec 1>&4 4>&1     # Restore stdout through reference in 4 and close 4
+# Everything back to normal
+```
+
+`mkfifo` creates a named pipe, which can be easier to interact with between
+scripts. Make sure it's being held open at use
+
+```bash
+mkfifo fifo
+cat fifo >ofif &   # Holds open fifo pipe and copies anything in there to ofif
+exec 3>fifo        # fd 3 reffers to pipe fifo
+echo "double" >&3  # Writes to fifo. >fifo would close the pipe right after
+exec 3>&-          # Manually close the open pipe
+```
+
+The example above works similar to `tee` in logging everything in the pipe
+

notes/shell/fzf_completion.md

@@ -0,0 +1,26 @@
+# Using fzf correctly
+
+```
+^r  Pull command out of bash history
+^t  Complete file names relative to cwd
+```
+
+Standard shortcuts
+
+```bash
+mv **<TAB>
+mv ./**<TAB>
+```
+
+When tabbing after `**`, fzf will complete the path. This works with other
+destinations like `~/Downloads/**<TAB>`
+
+Fzf also automatically completes most common commands, like `ssh`, `kill`, and
+`unset`. Note that most of these still require `**`, they just complete what's
+expected instead of file paths
+
+You can set up additional completions in a bash config file
+
+```bash
+_fzf_setup_completion path mpv
+```

notes/shell/git_notes.md

@@ -0,0 +1,206 @@
+## Quick start
+Git is an indispensable tool for code development, though in reality you'll only
+use a few commands on a day to day basis. This section provides a quick overview
+of those commands
+```
+    $ git fetch
+    $ git status -s
+    $ git diff file_1
+    $ git add some_dir
+    $ git commit -m "Changed some directory"
+    $ git switch -c new_branch
+    $ git restore file_2
+    $ git commit -a
+    $ git log --graph --all --oneline --decorate | less
+    $ git push
+```
+The above represent ~90% of git commands you'll use. For some of these, like the
+`git log` command, you should setup aliases
+
+#### Manual pages
+    $ man gittutorial
+    $ man giteveryday
+Some useful manual pages for referencing non-specifics
+
+    $ man git-rebase
+    $ git help rebase
+    $ tldr git rebase
+For information on a single command, add a hyphen to separate out the
+subcommand. If using `tldr` type the command as you normally would
+
+#### Referencing commits
+While most git commands default to `HEAD` without a commit passed, they often
+accept other commits to operate on. Some commands also need another commit to
+operate, like `git merge`
+
+    $ git show HEAD      # References the current HEAD
+    $ git show HEAD^     # References one commit above the HEAD
+    $ git show HEAD^^    # Two commits above HEAD
+    $ git show HEAD~4    # 4 commits above HEAD
+    $ git show a22a398   # Commit starting with SHA1 a22a398
+    $ git show v0.2.0    # Commit tagged with v0.2.0
+    $ git show master    # Tip of the master branch
+    $ git show origin/dev  # Tip of the local copy of the origin's dev branch
+Various examples of referencing commits. These can be mixed together for more
+complicated referencing, though that's not too common
+
+    $ git show HEAD~4..     # All commits from 4 commits before to HEAD
+    $ git show v2.0..HEAD^  # Commits from tag v2.0 to one before HEAD
+Some commands accept ranges of references. As expected, if one end of the range
+is missing, it'll use a default upper/lower bound
+
+    $ git merge origin/master^
+Merges one before the tip of the local copy of the origin's, possibly outdated,
+master branch to the current branch. Very useful when working offline
+
+## Project setup
+#### New projects
+    $ git init
+Create a new git repository in the current directory with a master branch
+
+    $ git remote add origin git@github.com:Aizuko/configs.git
+    $ git remote add origin ssh://git@github.com:22/Aizuko/configs.git
+Sets up a remote origin on GitHub. This example uses ssh to connect, though
+often http will also be supported. The second example specifies port 22
+
+    $ git push --set-upstream origin master
+Pushes the master branch to the remote origin
+
+#### Using a previous project
+    $ git clone ssh://git@github.com/Aizuko/configs.git
+    $ git clone https://github.com/Aizuko/configs.git
+Clone a git repository from a remote. Everything will automatically be setup
+
+    $ git clone -b dev --single-branch --depth=1 ssh://git@github.com:22/Aizuko/configs.git
+Clone the tip of the dev branch. Useful for saving storage, if you only need the
+latest commit
+
+    .git/config
+    [remote "origin"]
+     - fetch = +refs/heads/dev:refs/remotes/origin/dev
+     + fetch = +refs/heads/*:refs/remotes/origin/*
+Sets git to synchronize all branches from origin, instead of just `dev`
+
+    $ git remote -v
+List the remotes for this repository. Often useful if you want to change the
+connection protocol
+
+    $ git remote set-url origin git@github.com:Aizuko/configs.git
+Changes a remote. You'll rarely use this outside of changing protocols
+
+    $ git clone --depth=1 git://github.com/Aizuko/configs.git
+Quick way to clone a Github repository without needing to login
+
+    $ git remote add upstream git@github.com:22/Aizuko/configs.git
+Sets up another remote to track. Particularly important with forked branches
+
+## Branches
+Branches are a way to organize workflow into separate goals. This allows commits
+for a feature that is still in development. Git recommends making a lot of cheap
+branches and deleting them once merged
+
+    $ git branch -a
+Lists all the branches on the local system
+
+#### Git checkout changes
+`git checkout` was one of the most common commands to run in git, since it
+handled way too much. Starting in git 2.23 the command has been split into two
+new commands. `switch` deals with branches while `restore` resets files
+
+    $ git restore file.txt
+    $ git checkout file.txt
+Restore a file to how it was in the `HEAD's` commit
+
+    $ git restore --source HEAD^ file.txt
+    $ git checkout HEAD^ file.txt
+Restore the file to match the commit one before the `HEAD`
+
+    $ git switch master
+    $ git checkout master
+Switch to the `master` branch
+
+    $ git switch -c dev
+    $ git checkout -b dev
+Create a new branch called `dev`
+
+#### Removing branches
+Once a branch's goal has been achieved and merged, there's no use in keeping it
+around. Having a bunch of old branches is simply confusing
+
+    $ git branch --merged
+Shows which branches have been merged. Many of these are often safe to delete
+
+    $ git branch -d merged_branch
+Deletes a branch locally. Only deletes branches that have been fully merged into
+an upstream, so often the remote. There's no fear in losing commits this way
+
+    $ git branch -D deadend_branch
+    $ git branch -f -d deadend_branch
+Force deletes a local branch, regardless of whether it's been merged. You can,
+and likely will, lose commits this way. This should only be used for local
+experimental branches that quickly hit a dead end in development
+
+    $ git push origin --delete merged_branch
+Deletes the branch on the remote repository as well
+
+#### Tagging
+Tags can be added to make referencing certain commits easier. Tags can often be
+used instead of the rather complicated SHA1 to reference commits
+
+    $ git tag -a v0.1.0 a22a398
+    $ git tag -a v0.1.0 a22a398 -m "First version"
+Creates an annotated tag for the commit `a22a398`. The tag will be automatically
+signed
+
+    $ git tag -a -f v0.2.0 a22a398 -m "Add compact statusline"
+Overwrite previous tag for a commit with a new tag. This isn't a problem for
+tags that are only local to the system. Do not attempt for remote tags
+
+    $ git push origin v0.1.0
+    $ git push origin --tags v0.1.0 v0.2.0
+Push up locally created tags to the remote. Tags need to be explicitly pushed.
+Note that undoing tag pushes is really hard and shouldn't be done
+
+## Ignoring files
+In general there are 2 types of files you won't want to track with git: build
+artifacts and files specific to your computer. Stopping git from tracking these
+is done through git ignore pattern files
+
+    ./.gitignore
+Sits in the root of a git repository as a local ignore file. This will be
+committed to the repository, so other users will ignore the same files
+
+    ./.git/info/exclude
+Acts like a `.gitignore` file specific to your system's repository. It will not
+be committed. Useful for random files you have lying around
+
+    ~/.gitignore_global
+A `gitignore` that applies to every repository for the user. It will not be
+committed to any particular repository, so it's more similar to a git exclude
+file. It doesn't need any particular name, just source it in `~/.gitconfig`:
+```
+[core]
+	excludesfile = ~/.gitignore_global
+```
+
+`.gitignore` files use pattern matching similar to regex
+
+    target
+    target/**/*
+Ignores anything in and including the `./target` directory
+
+    target/notes_[0-9].md
+    target/notes_?.md
+Doesn't track any note files from 0-9, though will track anything higher, such
+as `target/notes_12.md`. A `?` matches any one character, in this case also
+matching `target/notes_a.md`
+
+    !target/*_notes_*/lec_*.md
+Track any lecture file in any notes directory in `target`. This can match paths
+like `target/cmput_notes_1/lec_2.md` and `target/japan_notes_12/lec_passive.md`
+
+    $ git rm --cached file.txt
+In shell, removes a currently tracked file from tracking. This won't remove the
+file from your system. Useful when you start ignoring a previously tracked file
+
+[//]: # ex: set ft=markdown:tw=80:

notes/shell/jq_json_query_parser.md

@@ -0,0 +1,32 @@
+# JQ, stream json parser
+
+`jq` is a minimal json parser that's pretty useful in shell scripts. It can
+quickly filter json outputs for reading something. Most languages, for example
+js, have much faster json-parsers built-in, so it's better to use those when
+possible
+
+Json output usually comes in one of two forms, either a single json object, or
+an array of jsons. To extract jsons we can use
+
+```bash
+yabai -m query --windows --window | jq '.'  # Already a single json
+yabai -m query --windows          | jq '.[]'  # Iterates through array
+```
+
+`jq` takes in a filter on the right side, after a pipe-like separator. The
+output will just be the that value for single fields
+
+```bash
+yabai -m query --windows | jq '.[] | .id'  # Id of every window
+yabai -m query --windows | jq '.[] | .id, .app' # ID and name
+yabai -m query --windows | jq '.[] | .frame.x'  # x field in frame field
+```
+
+Your output can be either raw values, json objects, or arrays:
+
+```bash
+yabai -m query --windows | jq '.[] | .id'  # Raw id
+yabai -m query --windows | jq '.[] | { id: .id }'  # Id objects
+yabai -m query --windows | jq '.[] | [{ id: .id }]'  # Id objects in individual arrays
+yabai -m query --windows | jq '[.[] | { id: .id }]'  # Id objects in one array
+```

notes/shell/ssh_notes.md

@@ -0,0 +1,134 @@
+# SSH
+OpenSSH (ssh) is a secure protocol for connecting to computers/servers remotely.
+Its uses are infinite, from connecting to clouds to making your laptop a desktop
+
+### Basics
+    $ ssh -p 10022 emiliko@192.168.0.12
+    $ ssh -p 10022 emiliko@localhost
+Connects to user `emiliko` on host address `localhost` via port `10022`. Port
+`22` is the default for ssh
+
+    $ ssh emiliko@68.185.68.169
+To connect over WAN, there're some additional setup on the server-side:
+ 1. Set your IPv4 address manually. This usually requires setting manual DNS
+   servers. `1.1.1.1` and `1.0.0.1` are a good choice
+ 2. Set up port forwarding for port 22 on the router to your manual local IPv4
+ 3. Find your router's public IP address and use that as the host address
+
+    $ dig +short myip.opendns.com @resolver1.opendns.com
+    $ host myip.opendns.com resolver1.opendns.com
+    $ curl --silent https://ifconfig.me/ip
+Finds your network's public IP address. This'll the server's be the host address
+
+### Setting up ssh and ssh keys
+    # pacman -S openssh
+Update or install ssh. It's often packaged as `openssh` and installs `ssh`
+
+    # systemctl enable sshd
+Starts up the ssh daemon. The system should now be able to accept ssh
+connections. On macOS, use Preferences -> Sharing -> Remote Login
+
+    $ ssh-keygen -t ed25519
+    $ ssh-keygen -t ed25519 -f ~/.ssh/arch_qemu_ed25519 -C "For arch qemu"
+Generate a `ed25519` key pair. Interactively or through flags, this will add a
+comment at the end of the public key and save it in the designated file
+
+    $ ssh-copy-id -i ~/.ssh/key_file.pub emiliko@localhost
+    $ cat ~/.ssh/key_file.pub | ssh emiliko@localhost "mkdir -p ~/.ssh && cat >>
+    ~/.ssh/authorized_keys"
+Copy an ssh key to the host. Either one will give you the power of ssh keys
+
+    $ ssh-keygen -pf ~/.ssh/key_file
+Change the passphrase on the key
+
+### Using ssh keys
+    $ ssh -i ~/.ssh/identify_file emiliko@localhost
+Login to user using the identity file. This points to your private key. If the
+file is secured by a passphrase, you'll need to retype it every time
+
+    $ eval $(ssh-agent) && ssh-add ~/.ssh/key_file.pub
+Start the ssh agent and add a key file to it. This uses the path of the public
+key file. The agent prevents the need to retype the passphrase on this terminal
+
+    $ ssh -A emiliko@localhost
+Forwards the ssh agent to the destination system. Only useful if you plan to ssh
+from that system
+
+    $ scp -P 10022 ~/file emiliko@localhost:~/dir/
+Copies file between systems. `cp` except across systems. This uses the same
+login methods, key or password, as `ssh`. Port option must be capitalized
+
+    $ scp ~/file alias:~/dir/
+Copies file between systems, using `alias` from `~/.ssh/config` as the
+destination system. This will automatically specify a user, identity key, etc...
+
+    $ ssh -L 2222:localhost:3333 emiliko@192.168.0.12
+Creates an ssh tunnel connecting localhost:3333 on the host server to port 2222
+on the client. Useful for webpages and IDE notebooks
+
+### SSH keys with git
+After setting up ssh keys in both GitHub and your computer, you'll need to
+change repositories to use ssh instead of the http protocol
+
+    $ git remote -v
+Echos a list of remote sources for the current repository. If the URLs start
+with `http`, ssh protocol is not being used to connect to the remote sources
+
+    $ git remote add origin git@github.com:Aizuko/configs.git
+    $ git remote set-url origin ssh://git@github.com:22/Aizuko/configs.git
+Use ssh protocol when connecting to remote origin. `add` is for new projects
+which don't have an origin yet. `set-url` is for existing projects using http
+
+### Mounting remote filesystems with SSHFS
+SSH can mount a remote file system as if it's a laggy disk connected to your
+system. This can be a nice way to locally view and edit remote files
+
+Disclaimer: These commands have only been tested on MacOS using macFUSE
+
+    $ mount
+Lists all the current mount points
+
+    $ mkdir ~/mnt
+    $ sshfs emiliko@192.168.0.12:/Users/emiliko ~/mnt
+    $ sshfs emi:/Users/emiliko ~/mnt
+Mounts the Emiliko's home directory to `~/mnt`. Do not try `emi:~/` as bash
+tilde will expand relative to the host. Specify the remote path from the root
+
+    $ umount emiliko@192.168.0.12:/Users/emiliko
+    $ umount !sshfs:1
+Unmount the remote filesystem. Remember to type out the full remote path
+
+    $ sshfs -o cache=no emi:/home/emiliko ~/mnt
+    $ umount !sshfs:3
+Disable caching to reconnect on every command. Prevents false directory listings
+
+    $ pgrep -lf sshfs
+    $ ps aux | grep -i sshfs
+    $ kill -9 10364
+    # umount -f ~/mnt
+Forcefully unmount the filesystem
+
+#### SSH Forwarding
+    $ ssh -p10011 -NL 7000:localhost:8080 emiliko@localhost &
+    $ ssh -NL 7000:localhost:8080 emi &
+Opens an ssh tunnel between `7000` on the client and `localhost:8080` on the
+server. Best used with `&`, as in line 2, to avoid obstructing the current pane
+
+#### SSH config
+    ~/.ssh/config
+    Host paraarch
+        User emiliko
+        Hostname 192.168.0.12
+        Port 22
+        IdentityFile ~/.ssh/parallels_arch_ed25519
+        IdentitiesOnly=yes
+Adds a new host `paraarch` to the ssh config. `paraarch` can be used instead of
+the host name and it will automatically specify these flags. `IdentitiesOnly`
+resolves some issues relating to multiple failed connection attempts
+
+    ~/.ssh/config
+    Host github.com
+        Hostname github.com
+        IdentityFile ~/.ssh/github_key_ed25519
+When pulling from remote origin `git@github.com`, this key will be used
+[//]: # ex: set ft=markdown:tw=80:

notes/shell/ssh_port_forwarding.md

@@ -0,0 +1,5 @@
+# SSH port forwarding
+    ssh -p10011 -NL 7000:localhost:8080 emiliko@localhost &
+Opens an ssh tunnel without obstructing the current terminal. Syntax for the
+tunnel looks like:
+    <client_port>:<url_from_host:host_port>

notes/shell/unix_bash.md

@@ -0,0 +1,406 @@
+# Bash
+###### Process priority
+Since the processor must decide priority, it uses a scale from -20 through 20 to
+rank what has priority, with -20 being the highest priority. By default,
+processes launched by the user start with a niceness of 0
+
+    # nice --10 ./start_qemu.sh
+    # nice -n -10 ./start_qemu.sh
+Starts the process, in this case `start_qemu.sh`, with a given niceness level,
+in this case `-10`. The `-n` option increments from the base value, usually 0
+
+    # renice -2 1244
+    # renice -n -2 1244
+Changes the niceness of a running process via process id, in this case 1244.
+`-n` increments niceness from the current value, in this case by `-2`
+
+    $ ps -fl -C 1244
+Check the niceness of process with id 1244
+
+###### Job Control in Bash
+You should not use jobs if you can help it! Especially when it comes to
+input/output jobs are terribly unclear. Only use them for tasks that will never
+ask for input or give an output. Use a multiplexer (`tmux`) instead
+
+    $ python -m SimpleHTTPServer 3000 &
+Starts a process, in this case the python server, in the background. Just append
+a `&` at the end
+
+*Oh no, I didn't launch the process in the background*
+    ^z
+If you want to move suspend the current process, `^z` will suspend and stop it
+
+    $ bg %2
+    $ bg 2
+    $ %2 &
+Continues the stopped job in the background. In this case, we use job identifier
+1, which will start that specific job. You can omit the `%` with `bg`
+
+    $ fg %2
+Bring a job back to the foreground. Uses identifiers much like `bg`
+
+    $ jobs -l
+List all background jobs running. `-l` shows their process id
+
+    $ kill %2
+Kills a background job, via identifiers. The `%` is not optional here!
+
+    $ wait %2
+Waits for job identifier `2` to finish. Passing no arguments waits for all
+background jobs
+
+    $ wlsunset -t 4000 -T 65000 -g 0.9 &
+    $ disown %1
+Launches `wlsunset` in the background. Then, assuming it's job 1 under `jobs`,
+disowns the process. The shell can now close with the process still running
+
+    $ wlsunset -t 4000 -T 65000 -g 0.9 & disown
+Same as above. More compact
+
+    $ { wlsunset -t 4000 -T 65000 -g 0.9 & } &
+    $ ( wlsunset -t 4000 -T 65000 -g 0.9 & ) &
+Same as above, background and disowns the subshell. `{}` execute the subshell in
+the current shell's context, while `()` start a fresh shell. `{}` are also used
+in brace expansion, so they need to be delimited by spaces
+
+
+###### Vim editing for Bash
+    $ set -o vi
+Makes bash use vi key binds. Note, this uses `vi` not `vim` bindings. Generally
+this isn't recommended, even for complete vim users
+
+    $ export EDITOR='vim'
+Bash will run the specified command when looking for an editor
+
+    <C-x><C-r>
+Open current shell line in editor. Really powerful for long lines
+
+See the (Ex section)[#Batch-editing-with-ex] for batch editing with vim
+in `ex` mode
+
+###### Stop yourself from deleting files
+    $ chmod a-w safe_directory
+Prevents writing to the directory. Writing, in the sense of editing files is
+still controlled by file permissions, you just can't remove or make new ones
+
+    # chown other_user safe_directory; chmod 755 safe_directory
+Makes another user own the directory. All others uses cannot make/remove files.
+Same as above, if ownership is given to root, though a bit more explicit
+
+    # touch safe_directory/file
+    # rm safe_directory/file
+You can still create and delete files in this directory with root
+
+###### Reusing commands
+See HISTORY EXPANSION in `man bash` for more information
+
+    $ sudo !!
+    $ sudo !-1
+Recalls the last command and runs it as root. Notice the `-1` can be any number
+to recall older commands
+
+    $ !man
+Rerun the last command starting with the string `man`
+
+    $ !?diff?:p
+Print the last command that contained the string `diff`
+
+    $ mv !:2 ../!:2
+Substitutes `!:2` with the second argument of the previous command. The command
+itself is `!:0`, so it's the second argument. Here it moves a directory up
+
+    $ mv !^ !^'_name'
+    $ mv !$ !$'_name'
+`$` and `^` are aliases for the first and last arguments. Here it changes a file
+or directory name by adding `_name` at the end
+
+    $ vim -p !touch:*
+    $ vim -p !touch:2-4
+    $ vim -p !:2*
+Expands argument ranges from the last `touch` command. `*`, `1-*` and `1*` are
+synonymous. If no string is specified, like `!:*`, the last command is used
+
+    $ vim -o !touch:1*
+Open a new window for every argument in the most recent command starting with
+`touch`
+
+    $ ^touch^vim -o^
+    $ !!:s/touch/vim -o
+    $ !!:&
+Replay the last command replacing the first instance of `touch` with `vim -o`.
+The third line replaces `&` with the last substitution
+
+    $ vim -o !touch:*:gs/html/md
+Recall all the arguments of the last `touch` command. Replace all instances of
+`html` with `md` then pass those to `vim -o`
+
+    $ cat !!:$:s/machine/human
+Substitute in the last argument from the previous command with `human`
+
+    <C-r>
+    <C-s>
+Search backward or forward for input string. Use multiple times to scroll
+
+    awk '{a[NR] = $0} END { for (i = NR; i > 0; i--) print a[i] }' # rev lines
+    <C-r># rev lines
+Replays the tagged command. Use trailing comments to act as a tag
+
+    diff ~/Downloads/{before,after}.txt
+Checks if `before.txt` and `after.txt` are different. Braces are duplicated
+
+    $ !if:gs/$c/$a
+Replace all the variables $c with $a in the previous command starting with if
+
+So the general structure of recall is
+```
+!<cmd-identifier>[:<arg-range>][:<operator>]
+```
+
+###### Automated interactive input
+    $ yes | rm -ir /deep_dir
+Bypasses interactive y/N prompt given by the `rm` command for every thing in that
+directory. `yes` prints an infinite number of 'y\n' to any program
+
+    $ printf 'y\nn\ny\n' | rm -ir /small_dir
+Will remove the first and third file automatically, then ask you for further
+input
+
+    $ rm -ir /deep_dir < pre_made_input.txt
+Enters the file contexts to the interactive prompt. Line breaks are like '\n'.
+Very helpful if you're using this order of input over and over
+
+###### Bash scripting
+Bash is an awful scripting language in every sense except portability. Always
+install and use `shellcheck` after writing a script
+
+    bash_script.sh
+    #!/bin/bash
+    #!/usr/bin/env bash
+    #!/usr/bin/env -S awk -f ${SOMEFILE}
+Use shebang at the top to declare an interpreter. Using `env` is considered more
+portable, though the `-S` option is required for anything longer than one word
+
+    $ echo ${myvar:-not here}
+    $ echo ${myvar:-"not here"}
+Expands to `$myvar` if it's set, otherwise expands to string "not here"
+
+    $ for i in $(seq 0 9); do python -c "print(ord('$1'))" & done
+Asynchronously print the ASCII codes for range `[0, 9]`
+
+###### Other Bash uses
+
+    $ compgen -c git
+See the possible completion for the given word. This is what tab uses
+
+    $ time bash -c "make && ./a.out; rm ./a.out"
+Times multiple separate bash commands
+
+## Ed for terminal file editing
+Ed is the original text editor for Unix systems, which still is useful for batch
+editing scripts. Ranges are very similar to vim's
+
+    $ ed -p '> :' file1
+Open `file1` with ed. Useful for writing a script
+
+    :n      Print the current line enumerated
+    :100    Moves to line 100 and prints it
+    :ka     Set a mark `a`
+    :'a     Move to mark `a`
+    :i      Open line above current line in insert mode. Like vim's `o`
+    :a      Open line below current line in insert mode. Like vim's `O`
+    .       Exit insert mode. Should be the only character on the line
+Various basic commands. Most commands accept ranges, like vim's. Unlike vim, all
+commands operate on entire lines at once
+
+    :g/Style/p\
+    a\
+    Style line is above ^^^^\
+    .\
+    n
+For all lines matching the regex, run the command sequence. `\` separate lines
+
+#### Batch editing with ex
+Ex is vim's equivalent of `ed` and `ex` is symlinked as `vim -e` on many
+systems. It's equivalent to vim's command line, similar to `ed`, though many
+commands are different
+
+    $ ex file
+    $ vim -Nes file
+Roughly equivalent ways of entering ex-mode. `Q` also works from within vim
+
+    :g/re/p         Globally exectute a command on lines with /re/
+    :v/re/p         Inverse of :g. Executes on all lines without /re/
+    :3,6co$         Copy lines [3,6] to the end of the document
+    :3m6            Move line 3 to line 6
+    :z=3            Pretty print lines in [-2,+2]
+Some infrequently used vim commands are very important in ex-mode
+
+    :g/re/z3
+Prints all the lines and line numbers that contain regex `re`
+
+    :g/bash/exe "normal! cfish\<esc>" | undo | nu
+Changes every line with "bash" to "fish", undoes that, then prints the line
+
+    :g/string/nu | g/num/nu
+Does NOT print all the lines with `string` or `num`. This prints all the lines
+with `string` then reprints them if they also have `num`. `:g` only uses a new
+line to delimit its commands from the next set!
+
+Batch editing style (in bash):
+ 1. Here-string: For only one command, here-strings are a quick and easy choice
+
+    $ for f in $(find ~/); do vim -Nes <<<"g/re/p"; done
+Prints all lines with `re` in the home directory. Be careful chaining with `:g`
+
+ 2. Here-ansi-c-string: Allows including c-style escape sequences
+
+    $ for f in $(find ~/); do vim -Nes <<< $'g/re/nu\n3'; done
+Prints all lines with `re` then moves to line 3. Often can be avoided with `|`
+
+ 3. Here-documents: Probably the best choice for quick batch edits
+
+    $ for file in $(fd -at type subs_)
+    do
+    vim -Nes $file <<'DOC'
+    g/^Stl/exe "norm! cStyle: new\<CR>\<esc>"
+    $ | a
+    # ex: ff=unix:
+    .
+    wq
+    DOC
+    done
+
+Changes The style lines and appends a modeline to files found by `fd`
+
+    $ for file in ~/.bash*; do vim -Nes $file <<EOF
+    a
+    # ex: set syntax=bash:ff=unix:
+    .
+    wq
+    EOF
+    done
+Adds a mode line to all bash dot files in the home directory
+
+ 4. Sourced documents: Better for recurring batch edits
+
+    $ fd -a subs_ -x ex < change_font
+    $ fd -a subs_ -x vim -Nes < change_font
+Changes font for all subtitle files. Similar to `vim -S $file`
+
+#### Best practices
+Use `-t file` in `fd`, otherwise `ex` may stop when it hits a directory
+
+Recent version of `fd` seems to consume here-documents and strings. To avoid
+this, use the bash `for` loop syntax as below:
+
+    $ for file in $(fd -at file .); do vim -Ne $f <<<$'nu'; done
+
+Or with here-documents
+    $ for file in $(fd -at file .); do vim -Ne $f <<doc
+    nu
+    doc
+    done
+
+#### Batch editing manually
+    fd -t file . -X awk '$0  ~ / ex:/ { print FILENAME }' | xargs -o vim
+Open all files containing ` ex:` in vim as separate buffers
+
+## Awk the programming language
+AWK is an old, though surprisingly useable stream-editing language. It's a POSIX
+compliant tool to bundle `grep`, `sed`, `printf`, `cut`, `xargs`, and more all
+into one scripting language. Most its use comes in bash scripts or one-liners to
+quickly extract information from a text stream. The man pages are really good!
+
+Much of the standard control flow is the same as C. Variables don't need to be
+initialized before use, ex: `i+=1`. Many functions will perform on `$0` if no
+argument is given
+
+    #!/usr/bin/env -S awk -f
+    #!/usr/bin/env -S awk -F: -f
+Use the string option on `env` to be able to specify the necessary `-f` option
+
+
+    substr(str, start_pos, chars_cut)   // Cut out part of a string
+    length([str])               // Length of str, or $0 if no argument is given
+    index(str, search_str)      // Find starting index of match in str
+    match(str, /reg/)           // Return index. Set RSTART and RLENGTH
+    split(str, array, fs)       // Split str into array elements on FieldSeperator
+    sub(/reg/, new_str, str)    // Subs new_str for first /reg/ match in str
+    sub("match", new_str, str)  // Subs new_str for first string "match" in str
+    gsub(/reg/, new_str, str)   // Above just global
+The core awk functions with odd argument order
+
+    printf, sprintf, system, tolower, toupper, exp, log...
+Core awk functions without odd argument order
+
+### Built in variables
+    NR  Current line's number. Literally "number of reads". Starts at 1
+    NF  Number of fields in this line. `$NR` expands to the last field's value
+    RSTART  Field number of last `match()`
+    RLENGTH  How many characters long the last `match()` was
+    $0  The entire line of text
+    $1  Where `1` is the `1th` field in the line
+
+### Regular expression
+Regular expressions are supported. They're a separate type from strings. Unlike
+most modern regex interpreters, escape sequences such as `\s` and `\d` aren't
+supported. Instead use POSIX compliant versions `[:space:]` and `[:digit:]`
+
+Inverting a regex is done by defining a `!` in front. For example
+    $0 !~ /hello/
+    $0 ~ !/hello/
+    $0 ~ /[^(hello)]/
+
+If you want to store a regex in a variable for later use, DO NOT store an actual
+regex type. Store the regex as a string instead, effectively replacing the
+encapsulating `/` with `"`
+
+    my_regex = "hello[:space:]+you"
+    $0 ~ my_regex
+Notably, using a regex instead of a string in this situation results in odd
+silent errors that mostly work. These can be hard to debug, so watch out
+
+### Recipes
+    $ cat file.txt | awk 'tolower($0) ~ /word/ { print $0 }'
+    $ cat file.txt | awk 'tolower($0) ~ /word/'
+    $ cat file.txt | grep -i 'word'
+Searches through given piped text for 'word' in any casing
+
+    $ cat file.txt | awk -F ',' '
+            { commas += NF - 1 }
+        END { print "Commas counted:", commas }'
+Counts the number of commas in a file.
+
+    $ awk -F '\t' '{ print $0 }' demo.txt
+    $ awk -F '\t' demo.txt
+Uses tabs are a files separator between "lines"
+
+    $ current_window_id=$(chrome-cli list windows | awk -F ' ' \
+            'NR == 1 { gsub(/[\[\]]/, "", $1); print $1 }')
+Parses the window id from `[999] Some Title` to `999`
+
+    $ ls -la | awk 'match($NF, /[0-9]+/) { print substr($NF, RSTART, RLENGTH) }' >
+    coffees.nh
+Checks if the last argument is a string of consecutive numbers. Notice how `$NF`
+uses that `NF` is the last number to index the last field like `$3`
+
+### Advanced examples
+    END {
+        arr["hello"] = 2; arr["other"]++; arr["some"] += 10;
+
+        printf "Hello: %d, Other: %d, Some: %d, None: %d\n",
+            arr["hello"], arr["other"], arr["some"], arr["none"];
+    }
+    >>> Output: Hello: 2, Other: 1, Some: 10, None: 0
+Arrays can be indexed by strings! This allows for counting words or lines
+
+    $ awk '!($0 in uniq) { uniq[$0]; print }' duplicates.txt > uniques.txt
+Removes duplicate lines. This uses the relational operator `(expr, expr... arr)`
+to check if an element with the string's index has been initialized in the array
+
+    $ awk '!unique[$0]++' duplicates.txt > uniques.txt
+Removes duplicate lines. This exploits awk's automatic initialization of
+variables with falsey values, 0 here, then turns that index truthy with `++`
+
+
+<!-- ex: set ft=markdown tw=80: -->

notes/shell/unix_file_times.md

@@ -0,0 +1,8 @@
+# Unix file times
+Unix files store 3 time stamps: Modified, Accessed, Changed. These can be seen
+with `ls -l`. The `stat` command can list these times as well, particularly with
+something like `--format='%y'`
+
+`touch` can change times directly. To use the times of another file, provide it
+via the `-r` option, then constrain the times you want to change. For example
+the `-m` flag will only copy over the modified time

notes/vim/tee.md

@@ -0,0 +1,32 @@
+# Tee command
+Duplicate piped output between a file and the stdout
+
+```bash
+sudo echo "something" > root_file
+```
+
+This won't work since output redirection is always done with user privileges.
+Instead we use:
+
+```bash
+echo "something" | sudo tee root_file
+echo "something" | sudo tee root_file &>/dev/null
+```
+
+Now the redirection will be executed with root privileges. Stdout can be
+silenced to get the same effect as before. Tee can also copy output to multiple
+files, or act like `>>` with `-a`
+
+```bash
+echo "something" | tee file1 | tee file2 > file3
+```
+
+It's very useful in vim, when you forget to use root privileges when editing a
+root-only file:
+
+```bash
+:w ! sudo tee %
+```
+
+Note that neovim doesn't support interactive sessions through external commands
+yet, so this only works in vim

notes/vim/vifm_moving_files.md

@@ -0,0 +1,46 @@
+# Vifm: Moving files
+
+There are a few ways to move files in vifm, all of which hinge on using a
+selection paired with some sort of command
+
+### Selections
+
+These selections and filters get cleared once you change directories
+
+ 1. Not selecting anything implicitly selects anything under your cursor
+ 2. `za` toggles dotfile visibility
+ 3. `t` adds a single file to the selection from the directory
+ 4. `V` visual mode selects files in a range
+ 5. `=` quick filter that is case-sensitive
+
+These filters are permanent, in that they're retained between directory
+switches and apply to all directories
+
+ 1. `zf` adds the current selection to the permanent filter
+ 2. `:filter <regex>` hides all matching files in all directories
+ 3. `:filter! <regex>` inverse of above filter, only shows these files
+
+These are then controlled with
+
+ - `zO` Unset the permanent filter
+ - `zR` Stash the permanent filter
+ - `zM` Pop the stashed permanent filters
+
+These are best paired with visual mode to quickly select a bunch of files
+
+### Moving files
+
+A simple `:m` will move all selected files to the location in the other pane.
+Using `:sync %d` can set the opposing pane to the current one
+
+Alternatively you can yank into a register, say `"ay`, then move all files in
+the register to your current location with `:put a`
+
+Also, don't forget there are other tools that can be better for the job. For
+example batch renaming should be done through `mmv`
+
+```
+:!mmv './*_EP*.srt' './Documents/subtitles/kaguya_S1_#1.srt'
+```
+
+Bash for-loops paired with `fd` or `rg -l` can be used for fine-tuning too

notes/vim/vim_backtick_expansion.md

@@ -0,0 +1,17 @@
+# Vim backtick expansion
+
+```
+:h backtick-expansion
+```
+
+Essentially allows command substitution with shell or vim commands. Requires a
+lot of escaping special symbols though
+
+```bash
+:e `mktemp`
+:e `=tempname()`
+```
+
+Edit a new temporary file. Very useful in gui contexts when you just quickly
+need to jot something down. The equal sign in the second line expands a vim
+function instead of calling a shell

notes/vim/vim_macros.md

@@ -0,0 +1,53 @@
+# Vim Power Macros
+
+### Recording
+
+When recording macros, best practice is to start with a `0` motion and try to
+use absolute motions to the line like `A` not `w`
+
+Macros are a register, so they can be edited the same way as one. In fact `@` is
+just a shortcut for `:normal <paste-register-here>`. They can be viewed with
+`:reg`
+
+Modifying macros:
+ - `"lp` paste register `l`
+ - `<C-v><C-k>` literally inserts `<C-k>` as a key motion. Useful for pseudo-esc
+
+Saving macros:
+ - `"lyy` copy line into register `l`
+ - `:'<,'>y l` copy selected line into register `l`
+ - `{Visual}"ly` copy selection into register `l`. Doesn't have `<C-j>` at the end
+
+On the line:
+ - `<C-r>l` pastes the `l` register in insert mode
+ - `:let @l = "<rec>"` sets the `l` register as `<rec>`
+ - `:let @L = "<rec>"` appends `<rec>` to register `l`
+ - `"i\<esc>"` in a string escapes to literal key strokes, like `<C-v>` inserts
+
+Escaping keystrokes, from the last example, only works with double quoted
+strings. You can check in `:reg` to see the literal expansion
+
+### Replaying macros
+The older convention for batch macros was adding `j` at the end of the macro,
+and using absolute motions:
+ - `4@l` replay the macro 4 times
+
+A newer solution is to execute registers over command line through `:normal`.
+Macros executed this way always starts in the left-most column, so prepend `0`
+to your macro for consistency
+
+Command style:
+ - `:norm[al][!] @l` can be used to replay macros. Keep the `!` to not use maps
+ - `:'<,'>norm! @l` replays the macro over every select line
+ - `:g/re/norm! @l` replays the macro over lines with a matching regex
+
+Oddly, while `:norm! @l` doesn't see maps for `@l`, it will see mapping in the
+register internally. So
+
+```
+:nnoremap <C-k> <esc>
+:let @l = "Ihello\<C-k>"
+:norm! @l
+```
+
+will still read `<C-k>` as `<esc>` when executing

notes/vim/vim_unicode_special_keys.md

@@ -0,0 +1,28 @@
+# Executing special keys
+
+Vim's `:exe[cute]` will read special keys when they're escaped in double quotes:
+
+```vim
+exe "normal! i\<C-v>u049c\<C-v>u03b1\<C-v>u03c4\<C-v>u212f!\<ESC>"
+" Writes Ҝατℯ
+```
+
+You can use this to quickly script difficult macros, like the one above
+
+```
+:exe "normal! i\<C-v>u049c\<C-v>u03b1\<C-v>u03c4\<C-v>u212f!\<ESC>"<CR>
+```
+
+# Effective Unicode in vim
+
+```
+Demo unicodes: │┌┴─┐
+```
+
+Use `ga` in vim to display encoding information about the character under the
+cursor. We'll use the hex value. In insert mode use `<C-v>u` followed by the hex
+number to type in Unicode literally. The above can be written with
+
+```
+:normal! i<C-v>u2502<C-v>u250c<C-v>u2500<C-v>u2510<ESC>
+```