folliehiyuki/linux_tips.md

## linux_tips.md

      
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    Configurations

Kernel modules

# /etc/modprobe.d/blacklist.conf
blacklist radeon # nvidia, i915, depends on hardware specs
blacklist iTCO_wdt # who wants watchdog on desktop tbh? (except shutdown might not work properly xD)
blacklist iTCO_vendor_support # watchdog
Boot options

loglevel=4 apparmor=1 security=apparmor nmi_watchdog=0
Swap


swapfile: see ArchWiki for Btrfs notes
# dd if=/dev/zero of=/swapfile bs=1M count=2048 status=progress
# chmod 600 /swapfile
# mkswap /swapfile
# swapon /swapfile
# echo "/swapfile none swap defaults 0 0" >> /etc/fstab


zram (see more here)
# echo "options zram num_devices=2" > /etc/modprobe.d/zram.conf

systemd: see ArchWiki
openrc: see GentooWiki
runit:
# /etc/runit/core-services/03-zram.sh

# ensure zram is ready
modprobe zram

# set compression algorithm
echo zstd > /sys/block/zram0/comp_algorithm
echo zstd > /sys/block/zram1/comp_algorithm

# set disksize
echo 2G > /sys/block/zram0/disksize
echo 2G > /sys/block/zram1/disksize

# set memory limit
echo 2G > /sys/block/zram0/mem_limit
echo 2G > /sys/block/zram1/mem_limit

# activate swaps
mkswap --label zram0 /dev/zram0
mkswap --label zram1 /dev/zram1

# swapon
swapon /dev/zram0
swapon /dev/zram1


encrypted swap


Typical /etc/fstab


ext4: some programs (like pyenv, Doom Emacs, ...) need stuff to be executable in /tmp

UUID=...  /      ext4  rw,relatime             0  1
UUID=...  /home  ext4  rw,relatime             0  2
UUID=...  /media ext4  rw,relatime,nofail      0  2
tmpfs     /tmp   tmpfs rw,nosuid,nodev         0  0
tmpfs     /run   tmpfs rw,nosuid,nodev,noexec  0  0

btrfs: nested subvolumes for performance: @/var/cache/xbps, @/var/tmp, @/tmp, @/srv

# Separated subvolume for /var/log is nice for troubleshooting
UUID=...	/		        btrfs	rw,noatime,compress=zstd,ssd,space_cache,commit=120,subvol=@	        0 1
UUID=...	/home		    btrfs	rw,noatime,compress=zstd,ssd,space_cache,commit=120,subvol=@home	    0 2
UUID=...	/var/log	  btrfs	rw,noatime,compress=zstd,ssd,space_cache,commit=120,subvol=@log	      0 2
UUID=...	/.snapshots btrfs	rw,noatime,compress=zstd,ssd,space_cache,commit=120,subvol=@snapshots	0 2

UUID=...	/media		        btrfs	rw,noatime,compress=zstd,space_cache,autodefrag,commit=120,subvol=@media     0 2
UUID=...	/media/.snapshots	btrfs	rw,noatime,compress=zstd,space_cache,autodefrag,commit=120,subvol=@snapshots 0 2

# This is useful for disk overview
UUID=...	/mnt/defvol-root  btrfs rw,noatime,compress=zstd,ssd,space_cache,commit=120,subvol=/        0 2
UUID=...	/mnt/defvol-media btrfs rw,noatime,compress=zstd,space_cache,autodefrag,commit=120,subvol=/ 0 2

UUID=...	/boot		    vfat	rw,noatime,...					0 2
tmpfs     /tmp        tmpfs rw,nosuid,nodev         0 0

voidvault has a more detailed filesystem structures.

Btrfs maintenance


/etc/cron.weekly/btrfs-scrub (do the same with btrfs balance if using RAID)

#!/bin/sh

btrfs scrub start /

# Scrub 1 disk at a time
while btrfs scrub status / | grep running; do
	sleep 20
done

btrfs scrub start /media

/etc/cron.weekly/fstrim

#!/bin/sh

fstrim /

Use snapper for cron snapshots is a no-brainer
Use btrbk for incrementally sending snapshots

Dependencies (some distros don't ship them by default or mark them as optional)


vifm needs python3-dbus for mounting usb devices
ranger needs python3-Pillow and ImageMagick for ueberzug and kitty image preview methods
mpDris2 requires python3-mutagen for displaying music covers
luakit need gst-libav, gst-plugins-base, gst-plugins-good for video playbacks.
qutebrowser needs pdf.js (Void) / pdfjs (Arch) to open pdf files in the browser (enable c.content.pdfjs = True in config file)

Other notes


disable coredump
android udev rules at /etc/udev/rules.d/51-android.rules
libvirt conf
cron job for ssd (which is easier?? than discard)
elogind is needed when using flatpak with apparmor installed (to get a proper $XDG_RUNTIME_DIR)
per-user services on Void Linux
hardening

disable ssh password authentication


Small fixes for things


Alacritty might not display italic fonts correctly in terminal apps (eg. neovim). See #1977.

# Clone the alacritty repo
git clone https://github.com/alacritty/alacritty.git
cd alacritty/

# Re-compile the terminfo as normal user
tic -xe alacritty,alacritty-direct extra/alacritty.info

# Double check the result
infocmp alacritty

Libreoffice might hang on startup because of OpenCL. Run it the 1st time with SAL_DISABLE_OPENCL=1 libreoffice then go to Tools -> OpenCL to turn it off.

Some notes for Bedrock Linux


build all kernels' initramfs manually (since default hook will not be triggered) with dracut/mkinitcpio/... from the strata that installs grub/systemd-boot/... (for less headache)
things to be installed on each strata

same fonts
cursor themes (set /usr/share/icons/default/index.theme for each strata too)


Knowledge from other people

@konomikitten

@nikitavoloboev

winny from @LinArcX