# Unix & Linux
# ++++ + +++++
12345678911234567892123456789312345678941234567895123456789612345678971234567898

## Set date
```
date +%Y%m%d -s "20231005"
date +%T -s "16:40:00"
```
## get date
```
date --utc
```

## select all directories inside a folder
```
shopt -s globstar
chmod g+s /var/www/**/*/
```
or
```
chmod -R a+X workspace/synergy
```
# add user to a group
- `usermod -a -G <group> <user>`
# to see user groups
- `id`

## copy without overwriting duplicate files
cp -n ./lib /usr/

## Set default C/C++ com1piler
export CC=/usr/bin/clang
export CXX=/usr/bin/clang++
export CPP=/usr/bin/clang-cpp-14
export LD=/usr/bin/ld.lld

## get binary file architecture
`file <binaryFile>`

## run a program on specific core (index 1)
## (not single threaded but non concurrent)
numactl --physcpubind=+1 ./bn_cl

## check attributes on directory
ls -ld directory/
## resolve all links to target
readlink -f <link>

# sudo compound/piped/multiple commands
sudo sh -c ""

# find open ports
netstat -na | grep -i LISTEN
netstat -f inet -na | grep -i LISTEN
# linux
sudo netstat --listen
sudo netstat -lntpd

# find process listening in on $PORT
lsof -n -iTCP:$PORT | grep LISTEN

# generate public and private key pair
mkdir ~/.ssh
chmod 700 ~/.ssh
ssh-keygen -t rsa

# to list sha256 of a key
ssh-keygen -lf ~/.ssh/id_rsa.pub

# sshd: no hostkeys available -- exiting
ssh-keygen -A

# prin sha256 of a key
ssh-keygen -lf .ssh/id_rsa.pub

# letsencrypt ssl certs
sudo letsencrypt certonly --standalone -d ferryfair.com -d FerryFair.com -d www.ferryfair.com -d WWW.FerryFair.com -d rosy.ferryfair.com -d Rosy.FerryFair.com -d mail.ferryfair.com -d mail.FerryFair.com -d roundcube.ferryfair.com -d RoundCube.FerryFair.com -d fairplay.ferryfair.com -d FairPlay.FerryFair.com -d ferry.ferryfair.com -d Ferry.FerryFair.com -d mysqlclient.ferryfair.com -d squirrelmail.ferryfair.com -d vpn.ferryfair.com -d RPi1B2.ferryfair.com -d RPi3B.ferryfair.com -d RT-N18U.ferryfair.com -d Deepthi-PC.ferryfair.com -d RPi3BP.ferryfair.com -d underconstruction.ferryfair.com -d BPiCM4.ferryfair.com -d Core3566.ferryfair.com

certbot renew

Necktwi@Core3566 ~/workspace/acme-tiny $ python acme_tiny.py --disable-check --account-key ~/account.key --csr ~/domain.csr --acme-dir ~/workspace/WWW-development/.well-known/acme-challenge/ > signed_chain.crt
sudo cp signed_chain.crt /etc/letsencrypt/live/ferryfair.com/signed_chain.crt

# CA certificat autority certificates location
/etc/ssl/certs/ca-certificates.crt

## ssh-agent
### list keys
ssh-add -l/-L
### start agent
ssh-agent
### remove all ssh agent keys
ssh-add -D
### or just stop ssh agent on macOS
killall ssh-agent
### disable on macOS
launchctl disable "gui/$(id -u)/com.openssh.ssh-agent"

# to check cert.pem expiry date check for "Not After" in the output of
openssl x509 -in /etc/letsencrypt/live/ferryfair.com/cert.pem -text
### convert to pem
ssh-keygen -f ~/.ssh/id_rsa.pub -e -m PKCS8 > ~/.ssh/id_rsa.pub.pem
### encrypt
echo "hello gowtham" | openssl rsautl -encrypt -pubin -inkey ~/.ssh/id_rsa.pub.pem > hello.crypt
### decrypt
openssl rsautl -decrypt -inkey ~/.ssh/id_rsa -in hello.crypt
# print the private key contents
openssl rsa -in ~/.ssh/id_rsa -noout -text

# to view the key in hex and ascii
cat | base64 -d | xxd
MIIEpAIBAAKCAQEA7dDtxLPmGkHusoBr7dortWhypPX9nsV4Z6zeXuTl2bT9EuTT
Q9hcuGGmmqlvnqjkhkNaEwzOiR2ExJKoZpT8uu44qrgGQ37agxZFfK8YKGnQlGIu
xZFqd5e+5RWcP1e0kotsFVKDOUMP1IQFpSJD7ElSS+Y44dDuMne2U44emGGHZ/Lc
...
vmT+J+xze0D6MwXGJaumH+5LT7HM3QjLgwBLeamX1rrQ/HeFX9cm3w==
C-d
00000000: 3082 04a4 0201 0002 8201 0100 edd0 edc4  0...............
00000010: b3e6 1a41 eeb2 806b edda 2bb5 6872 a4f5  ...A...k..+.hr..
00000020: fd9e c578 67ac de5e e4e5 d9b4 fd12 e4d3  ...xg..^........
...
00000490: ee4b 4fb1 ccdd 08cb 8300 4b79 a997 d6ba  .KO.......Ky....
000004a0: d0fc 7785 5fd7 26df

# gpg - gnupg
gpg --list-keys
gpt --edit-key
> list
> expire
> save
gpg --list-secret-keys --keyid-format=long
gpg --export-secret-keys <keyid> > my.key
scp my.key remote:~/
# on remote
gpg --import my.key
gpg --list-secret

#print key in ascii
gpt --armor --export <keyid>

## vi commands
:help
C-] #open help under cursor
:set nonu
:set nu
/
n # next match
N # previous match
:s/foo/bar/gc # replace on current line
:%s/foo/bar/g # replace all in current line
G
u undo
C-r redo
:tabnew
:tabe
:tabp
:tabn
vi -b binary_file
:%!xxd
edit
:%!xxd -r
:wq
:set paste # no auto-indent when pasting text
:set nopaste # turn off paste mode after pasting data
:e #reload the file

# set vi tab size
set tabstop=3 softtabstop=0 expandtab shiftwidth=3 smarttab

# vimdiff
]c - next difference
[c - previous difference
do - diff obtain
dp - diff put
zo - open folded text
zc - close folded text
:diffupdate	- re-scan the files for differences
:diffg RE " get from REMOTE
:diffg BA " get from BASE
:diffg LO " get from LOCAL
v -select text
C-v -rectangular select
d -cut
y -copy
P -paste

## diff two directories
diff -qr dir1 dir2

## convert all files in dir
for entry in ./*.mkv; do ffmpeg -i "$entry" -codec copy "${entry%.*}.mp4"; rm $entry; done

## match numerics
shopt -s extglob
ls Arrow.S04E+([0-9]).mp4

#redirect stderr and stdout
cmd >>file.txt 2>&1

## mount samba shares
`sudo mount -t cifs -o username=Necktwi,password=tornshoes,vers=1.0 \
//192.168.0.1/Lake/ /mnt/Lake/`

## umount all samba share
umount -a -t cifs -l

## mount nfs
`sudo mount -t nfs 192.168.2.4:export/IceCap/Gowtham /tmp/IceCap`
### fstab
`192.168.100.3:/Ganges /mnt/Ganges nfs noatime 0 0`

## mount exfat
sudo mount -o "defaults,uid=1000,gid=1000,dmask=0002,fmask=0003" /dev/sda2 \
/mnt/ssd2/

## kill unresponsive ssh sessions
<Enter>~.

## Tunneling
### to map remote port 3000 to local port 8080
ssh admin@server1.example.com -L 8080:server1.example.com:3000
L4070 localhost:4000
L7011 localhost:1111
L7022 localhost:22
L7088 localhost:8888

#### on macOS
`sudo ssh -L 192.168.0.101:80:192.168.2.4:80 -N gowtham@127.0.0.1`
`sudo autossh -M 20000 -f -L 192.168.0.101:80:192.168.2.4:80 -N gowtham@127.0.0.1`

### to map local port 22 to remote port 3022 on remote server
#set `GatewayPorts yes` in `/etc/ssh/sshd_config` of remote server
#-N doesn't open a shell
#-f runs in background
`ssh -f -N Necktwi@rpi3b.ferryfair.com -R 3022:localhost:22`
#to auto reconnect
`autossh -M 20000 -f -N rpi3b.ferryfair.com -R 3022:localhost:22 -C`

### to debug ssh; find config location
ssh -vvvv <ip>

### ssh x forward
ssh -Y user@ip

## Mount remote folder using ssh
sudo sshfs -o auto_cache,reconnect,no_readahead,allow_other,IdentityFile=/home/gowtham/.ssh/id_rsa -o uid=999,gid=999, -o defer_permissions,noappledouble,nolocalcaches,local,volname=BBB -o debug,sshfs_debug,loglevel=debug gowtham@ubuntuvm.ferryfair.com:/home/gowtham/bbb_mount /home/ubuntu/Projects

### to allow root to access sshfs mount
sshfs -o allow_other 10.138.138.16:/mnt/ssd2 /home/amd/MI200-EthanolX/

## append local file to remote file or send text over ssh
cat .ssh/id_rsa.pub | ssh 10.138.138.16 -T "cat >> ~/.ssh/authorized_keys"

## Mount a folder
mount --rbind /dev /mnt/dev
mount --bind ~/ /export

## Mount iso


## Unmount remote folder
sudo fusermount -u /home/ubuntu/Projects

# Lazy unmount. Detach the filesystem from the filesystem
# hierarchy now, and cleanup all references to the filesystem as soon as
# it is not busy anymore. (Requires kernel 2.4.11 or later.)
sudo umount -l /mnt/backup

### if target is busy while umount
`lsof | grep /path/to/mountpoint`
- or
`fuser -mv /path/to/mountpoint`

## add a service or daemon at startup
update-rc.d defaults
## set run
update-rc.d disable [ S|2|3|4|5 ]
update-rc.d enable [ S|2|3|4|5 ]

update-rc.d -f remove
# Remove a service
sudo update-rc.d -f apache2 remove

## Searching for a file
```
find / -iname “*.conf”
find / -regex "+.\.[ch]$'
find /bin -lname busybox -delete
find / -type d \( -path /etc -o -path /data -o -path /usr -o -path /var \
-o -path /tmp \) -prune -name java
find . -not -path "*.cache*" -name velodyne128_detection_conf.pb.txt
# to exclude symlinks
find /root/ -type f -name magisk_patched-27000_xMP6j.img
```

## Searching for a text in files
#-I to ignore binaries
#-R follows symlinks, -r won't
#-i to ignore case
#-w whole word
#-n print line number
#--exclude-dir=dir
#--include="*.txt" to search only txt files
grep -rnw '/path/to/somewhere/' -e "pattern"

## extracting pattern
rocprof --list-derived | sed -nE 's/^.+: (.+) :.+$/\1/p'

### multiline sed example | extract ip
ipconfig | sed -n '/Ethernet 9:/, /Ethernet/p' | sed -nE 's/^.+IPv4\sAddress.+:\s(.+)$/\1/p'
or
ip addr | sed -n '/eno1/, /inet6/p' | sed -nE 's/.*inet (.+)\/.+$/\1/p'

## Replace string in files
perl -i -pe 's/ffjson.h/FFJSON.h/g' ./*
or
grep -rl --exclude-dir={*.git,dir2} /path/to/folder | xargs sed -i s^^^g

## Replacing file names
rename 's/ACDC/AC-DC/' *.xxx

## Remove a folder from path
PATH=$(echo "$PATH" | sed -e 's/:\/home\/wrong\/dir$//')
or
PATH=${PATH//$SEARCH_STRING/$REPLACE_STRING}

## copy with xargs
```
find modules/prediction/ -iname *.pt | xargs cp -t /mnt/ssd2/pts/
#or
find modules/prediction/ -iname *.pt | xargs -Issss cp ssss /mnt/ssd2/pts/
```

## Graphics driver
lshw -c video
modinfo -F filename `lshw -c video | awk '/configuration: driver/{print $2}' | cut -d= -f2`

## Get the info on loaded drivers
modinfo <modname>
## load moudle
modprobe <modname>
## force load module
insmod <modname>
## list all modules
lsmod

## turn off display from command line
sleep 1 && xset -display :0.0 dpms force off

## Get Resolution
fbset -s

## get edid
```bash
sudo apt install read-edid
sudo find /sys | grep -i edid
cat /sys/devices/platform/soc/soc:gpu/drm/card0/card0-HDMI-A-1/edid | parse-edid
```

## Get screen id or multi monitor/display coordinates
- `xrandr`
- to control display from remote terminal `export DISPLAY=:0.0`

## Set Resolution
```bash
xrandr --output Virtual1 --mode 1280x800
cvt 1280 800
cvt 1440 810
: <<'OUTPUT'
1280x800 59.81 Hz (CVT 1.02MA) hsync: 49.70 kHz; pclk: 83.50 MHz
#Modeline "1280x800_60.00"   83.50  1280 1352 1480 1680  800 803 809 831 -hsync +vsync
sudo xrandr --newmode "1280x800_60.00"  83.50  1280 1352 1480 1680  800 803 809 831 -hsync +vsync
xrandr | grep -e " connected [^(]" | sed -e "s/\([A-Z0-9]\+\) connected.*/\1/"
OUTPUT
```

## addmode
```
sudo xrandr --addmode eDP-1 1280x800_60.00
vi ~/.xprofile
#!/bin/sh
xrandr --newmode "1280x800_60.00"  83.50  1280 1352 1480 1680  800 803 809 831 -hsync +vsync
sudo xrandr --addmode eDP-1 1280x800_60.00
xrandr --output DSI-1 --scale 0.75x0.75
```

## startx on a virtual console if no xinit for the user
if [ "$(rc-status -r)" = "x" ] && [ -z $DISPLAY ] && [ $(tty | grep "/dev/tty[1-6]") ] && ! [ $(pgrep -U $UID xinit) ]; then startx; fi

## vnc
- `sudo x11vnc -display :0 -auth /var/run/lxdm/lxdm-\:0.auth -forever -noxdamage -nopw`
## switch to dGPU
glxinfo | grep "OpenGL renderer"
xrandr --listproviders
xrandr --setprovideroffloadsink <provider/1> <sink/0>
DRI_PRIME=1 glxinfo | grep "OpenGL renderer"

__GLX_VENDOR_LIBRARY_NAME=intel __VK_LAYER_NV_optimus=non_NVIDIA_only VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/intel_icd.x86_64.json __NV_PRIME_RENDER_OFFLOAD=0 DRI_PRIME=0 ./simulator

__GLX_VENDOR_LIBRARY_NAME=nvidia __VK_LAYER_NV_optimus=NVIDIA_only VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/nvidia_icd.json __NV_PRIME_RENDER_OFFLOAD=1 DRI_PRIME=1 ./simulator

VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/intel_icd.x86_64.json vkcube

## set console mode or resolution
vi /etc/default/grub
GRUB_GFXMODE=1366x768
GRUB_GFXPAYLOAD_LINUX=keep

#if text mangles in nano or emacs then do terminal reset

## record screen
```
ffmpeg -video_size 1500x2160 -framerate 25 -f x11grab \
-i :0.0+<xinit>,<yinit> screenreocrd1.mp4
```

## amd gpu
```
echo "on" | sudo tee /sys/class/drm/card2/device/power/control
cat /sys/class/drm/card2/device/power/runtime_status
echo "high" | sudo tee /sys/class/drm/card2/device/power_dpm_force_performance_level
```

## nvidia gpu
```
nvidia-smi --query-gpu=name,power.limit,power.draw --format=csv
sudo nvidia-smi -pl 125
```
## insert service in run-command tree
insserv /etc/init.d/myservice
insserv -r /etc/init.d/myservice

sudo service openvpn@client start

# live log file
tail -f /var/log/ferryfair.log

# live log folder
inotifywait -m /proc -e create -e moved_to |
    while read dir action file; do
        echo "The file '$file' appeared in directory '$dir' via '$action'"
        # do something with the file
    done

# mount all fstab
sudo mount -a
# remount incase any error
sudo mount -o remount,
#source #destination #fs-type #mount-options(auto/noauto,rw/ro,exec/noexec,
user/nouser,ro/rw,sync/async

# fstab for sshfs
sshfs#gowtham@192.168.2.23:/media/Tin /media/Tin fuse defaults,allow_other,IdentityFile=/home/gowtham/.ssh/id_rsa 0 0

# mount udf
sudo mount -t udf /dev/sda1 /media/BitCoin
# or
sudo mount -t iso9660 /dev/sr0 /cdrom

# check disk for badblocks
sudo badblocks -sv /dev/sda | tee /media/Aren/bad-blocks-result

# repair disk with badblocks
sudo fsck -t udf -l /media/Aren/bad-blocks-result /dev/sda1
# repair root partition
sudo touch /forcefsck
btrfs check --repair /dev/sdb3
#/etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

auto eth0
# triggers upon hardware interaction
allow-hotplug eth0
iface eth0 inet static
address 10.0.0.41
netmask 255.255.255.0
network 10.0.0.0
broadcast 10.0.0.255
gateway 10.0.0.1
dns-nameservers 10.0.0.1 8.8.8.8
dns-domain acme.com
dns-search acme.com

auto eth1
allow-hotplug eth1
iface eth1 inet dhcp

allow-hotplug wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

auto eth1
allow-hotplug eth1
iface eth1 inet dhcp
post-up addr add 192.0.2.200 dev eth0

# /etc/wpa_supplicant.conf
country=IN
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
ssid="Kudupudi"
psk="16181631729"
priority=5
id_str="Kudupudi"
}

## ping/broadcast all ips in subnet/lan
nmap -n -sP 192.168.13.0/24

## to find route or hops to an IP
- `mtr`

## find MAC or HW address of systems on LAN
arp #if it doesn't list all, ping the missing ip and rerun

## DHCP
sudo nmap --script broadcast-dhcp-discover

## network
echo 1 > /proc/sys/net/ipv4/ip_forward

## forward all traffic another computer
./sshuttle -r MI200-EthanolX 0.0.0.0/0 -vv

## Internet speed test
- `curl -s \
  https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest.py | \
  python3 -`

# change sound card boot priority
sudo nano /etc/modprobe.d/alsa-base.conf
# comment options snd-usb-audio index=-2
sudo vi /lib/modprobe.d/aliases.conf
# comment options snd-usb-audio index=-2
sudo vi /usr/share/alsa/alsa.conf
# change all card 0 to card 1

# play sound from multiple speakers or devices
pactl load-module module-combine-sink

## stream sound
- sink: `ffplay -nodisp -fflags nobuffer -flags low_delay -probesize 32 -analyzeduration 0 -f s16le -ar 44100 -ac 2 udp://0.0.0.0:5000`or`nc -u -l -p 5000 | pacat --format=s16le --channels=2 --rate=44100 --latency-msec=10`
  - pacat crackles
- source: `parec -d alsa_output.pci-0000_00_1f.3.hdmi-stereo.monitor --format=s16le --channels=2 --rate=44100 --latency-msec=10 | nc -u 192.168.2.3 5000`

# view partition table
fdisk -l
## to fix partition order in fdisk
```
x
f
```
 
## change UUID
- umount /dev/sdb1
- tune2fs -U random /dev/sdb1

## find the process keeping device busy from unmount
`fuser -mv /path/to/mountpoint`

# check for fuse
grep -i fuse /lib/modules/$(uname -r)/modules.builtin

# check fuse version
fusermount -V

# check if a filesytem is supported e.g. udf
cat /proc/filesystems

## track progress of dd with pipe viewer;
```
# for linux bs=4M, skip n seek to dd from any point
dd if=some.iso bs=4m skip=500 conv=noerror,sync | pv | \
dd of=/dev/sdb bs=4m seek=500 conv=noerror,sync
or
Ctrl + t
pkill -INFO -x dd
or
dd if=/media/necktwi/Ventoy/lubuntu-24.04.2-desktop-amd64.iso bs=4M conv=noerror,sync of=/dev/sdb status=progress
```
## quickly create a huge garbage file
`fallocate -l 10G gentoo_root.img`

# save history to a file
history -w source1.sh
# clear history
history -c
# load history
history -r source1.sh

# in the ~/.bashrc put
# update history for every command
# Avoid duplicates
HISTCONTROL=ignoredups:erasedups
# When the shell exits, append to the history file instead of overwriting it
shopt -s histappend
# After each command, append to the history file and reread it
PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND$'\n'}history -a; history -c; history -r"
# for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
HISTSIZE=100000
HISTFILESIZE=100000

# startup daemon
chkconfig --add /etc/init.d/zoneedit

# mail
echo "message" | mail -s "Subject" -t to@address.com -A ~/Attachment1 -A ~/Attachment2

# flush mail queue or outbox
sendmail -bp

# login as different user
su - another_user

# run a command as another user
sudo runuser -u transmission -- touch /mnt/IceCap/Gowtham/movies/test

# Restart networking
sudo ifconfig eth0 down && sudo ifconfig eth0 up
sudo ip link set eth0 down && sudo ip link set eth0 up
sudo service network-manager restart

## assign static ip
```
ifconfig eth0 192.168.2.2/24
rotue add default gw 192.168.2.1
ip addr change 192.168.2.1/24 dev eth0
ip route add default via 192.168.2.1 dev eth0
ip route
```

# Set prompt
echo "PS1='${debian_chroot:+($debian_chroot)}\[\033[00;34m\]\h\[\033[00m\]:\[\033[00;34m\]\W\[\033[00m\] ${USER}\[\e[00;33m\]\$\[\033[00m\] '" >> /etc/bash.bashrc
PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\h:\W ${USER}\a\]$PS1"
PS1='${debian_chroot:+($debian_chroot)}\h:\W ${USER}\$ '
PS1='\[\033[00;36m\]\h\[\033[00m\]:\[\033[00;36m\]\W\[\033[00m\] ${USER}\[\e[00;33m\]\$\[\033[00m\] '
PS1='\[\033[00;31m\]\h\[\033[00m\]:\[\033[00;36m\]\W \[\033[00m\]\# '
PS1='\[\033[00;31m\]${HN}\[\033[38;5;256m\]:\[\033[38;5;27m\]\\
W \[\033[38;5;256m\]#\[\033[00m\]\n'
PS1='\[\033[38;5;77m\]${HN}\[\\
033[38;5;256m\]:\[\033[38;5;27m\]\W \[\033[38;5;11m\]\\[\033[38;5;27m\]\u\[\033[00m\]$\[\033[00m\]\n'

# tar extract zipped archived file
tar -xzvf file.tar.gz
# tar create zipped archived file
tar -czvf filename.tar.gz folder
# tar extract tbz2
tar -xjvf file.tbz2
gunzip -k file.gz
tar -xvf file.tar.xz
tar -xvf file.tar.bz2
bzip2 -dk filename.bz2
unxz file.xz
# tar -C /target/directory
# tar --strip-components=1 to righ away extract contents of sub folders
# extract specific file
tar -xf file.tar.xz "/file/to/extract.png"
# extract zip file
unzip file.zip -d destination_folder
# zip folder
`zip -r LTJoiningDocs.zip LTJoiningDocs/`
# extract .7z
`7zz -x compressed.7z`

## fonts
/etc/fonts/fonts.conf
/usr/local/share/fonts
cp *.ttf /usr/local/share/fonts/
fc-list #list fonts
## font kerning
- allows to mix different syllables in to a character in the featured languages

# wildcard or glob hidden files
GLOBIGNORE=".:.." ls -la *
shopt -s dotglob
# ls colors
LS_COLORS="$LS_COLORS:rs=0:di=0;36:ln=0;37:mh=00:pi=40;33:so=0;35:do=0;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=0;32:*.tar=0;31:*.tgz=0;31:*.arc=0;31:*.arj=0;31:*.taz=0;31:*.lha=0;31:*.lz4=0;31:*.lzh=0;31:*.lzma=0;31:*.tlz=0;31:*.txz=0;31:*.tzo=0;31:*.t7z=0;31:*.zip=0;31:*.z=0;31:*.Z=0;31:*.dz=0;31:*.gz=0;31:*.lrz=0;31:*.lz=0;31:*.lzo=0;31:*.xz=0;31:*.zst=0;31:*.tzst=0;31:*.bz2=0;31:*.bz=0;31:*.tbz=0;31:*.tbz2=0;31:*.tz=0;31:*.deb=0;31:*.rpm=0;31:*.jar=0;31:*.war=0;31:*.ear=0;31:*.sar=0;31:*.rar=0;31:*.alz=0;31:*.ace=0;31:*.zoo=0;31:*.cpio=0;31:*.7z=0;31:*.rz=0;31:*.cab=0;31:*.wim=0;31:*.swm=0;31:*.dwm=0;31:*.esd=0;31:*.jpg=0;35:*.jpeg=0;35:*.mjpg=0;35:*.mjpeg=0;35:*.gif=0;35:*.bmp=0;35:*.pbm=0;35:*.pgm=0;35:*.ppm=0;35:*.tga=0;35:*.xbm=0;35:*.xpm=0;35:*.tif=0;35:*.tiff=0;35:*.png=0;35:*.svg=0;35:*.svgz=0;35:*.mng=0;35:*.pcx=0;35:*.mov=0;35:*.mpg=0;35:*.mpeg=0;35:*.m2v=0;35:*.mkv=0;35:*.webm=0;35:*.ogm=0;35:*.mp4=0;35:*.m4v=0;35:*.mp4v=0;35:*.vob=0;35:*.qt=0;35:*.nuv=0;35:*.wmv=0;35:*.asf=0;35:*.rm=0;35:*.rmvb=0;35:*.flc=0;35:*.avi=0;35:*.fli=0;35:*.flv=0;35:*.gl=0;35:*.dl=0;35:*.xcf=0;35:*.xwd=0;35:*.yuv=0;35:*.cgm=0;35:*.emf=0;35:*.ogv=0;35:*.ogx=0;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:"
## sync copy excluding subfolders.
#use -z to delete files in destination that are not in source.
#use -R to create parent directories
#-a is archive mode which does recursion and preserves almost everything
#-v verbose, --stats
rsync -avuh --progress --info=progress2 -e 'ssh -p $port' -R /mnt/IceCap/ 192.168.1.101:/mnt/Aren --exclude=workspace/Linux.git --exclude=.git --exclude=var --exclude=tmp --exclude=.cache --exclude=.bash_history --exclude=backups

## Compile Linux kernel
```
# arbitrary precision numeric processing language. Syntax is similar to C
pacman -S bc
cd /usr/src/linux
make O=~/.build/kernel distclean
lspci -k //give currently loaded modules
make O=~/.build/kernel list-defconfigs #./arch/*/configs/
make kernelversion
make help
make O=~/.build/kernel menuconfig
or
emerge --config sys-kernel/gentoo-kernel
# create defconfig
make LLVM=1 LLVM_IAS=1 ARCH=arm64 HOSTCC=clang         CC=aarch64-gentoo-linux-musl-clang savedefconfig
mv defconfig arch/arm64/configs/luckfox_core3566_linux_defconfig
# if upgrading kernel version place old .config in new kernel tree and do
make olddefconfig
# generates .config based on currently loaded modules
make localmodconfig
zcat /proc/config.gz > .config #if not there do `modprobe configs`
scripts/config --disable SYSTEM_TRUSTED_KEYS
scripts/config --disable SYSTEM_REVOCATION_KEYS
#for vmware fusion CONFIG_FUSION_SPI=Y
#if clang, set LLVM=1 LLVM_IAS=1
#if arm64, export ARCH=arm64 SUBARCH=arm64 CC=clang LD=ld.lld
ARCH=arm CROSS_COMPILE=armv6zk-unknown-linux-musleabihf- make -j2
make INSTALL_MOD_PATH="/" modules_install
make INSTALL_PATH="/boot" install
cp /boot/vmlinuz-* /boot/efi/boot/bootx64.efi
make headers_install
emerge --ask sys-kernel/genkernel
genkernel --lvm --mdadm --install initramfs
mount -o remount,rw /sys/firmware/efi/efivars
```

## debugging a kernel
- kdb
- kgdb - more robust than kdb
- debugfs: `sudo mount -t debugfs`
## Ways to communicate between the userspace and kernel space
- IOCTL : Input and Output Control used for operations does not have a system
  call by default. steps to implement ioctl command:
  1. Create IOCTL command in the driver
     - define the IOCTL command:
       ```
       #define "ioctlName" __IOX("magicNumber", "commandNumber", "argType")
       ```
     - IOX: IO, IOW, IOR, IOWR
     - magicNumber: differentiates our set of ioctl calls from the others;
       device major number can be used here.
     - commandNumber: differentiates ioctls among our set.
     - argType: type of data, e.g. int32_t*
  2. Write IOCTL function in the driver
     ```
     int ioctl (struct inode* inode, struct file* file, uint cmd, ulong arg)
     ```
     - inode: inode number of the file being worked on
     - file: file pointer that was passed by the application
     - cmd: command that was called from userspace
     - arg: arguments passed from the userspace
     - `fops` pointer `unlocked_ioctl` shoult be pointed to `etx_ioctl`
       ```
       static long etx_ioctl(struct file* file, uint cmd, ulong arg) {
          switch(cmd) {
             case WR_VALUE:
                if (copy_from_user(&value ,(int32_t*) arg, sizeof(value))) {
                   pr_err("Data Write : Err!\n");
                }
                pr_info("Value = %d\n", value);
                break;
             case RD_VALUE:
                if (copy_to_user((int32_t*) arg, &value, sizeof(value))) {
                                pr_err("Data Read : Err!\n");
                }
                break;
             default:
                pr_info("Default\n");
                break;
          }
          return 0;
       }
       static struct file_operations fops = {
          .owner          = THIS_MODULE,
          .read           = etx_read,
          .write          = etx_write,
          .open           = etx_open,
          .unlocked_ioctl = etx_ioctl,
          .release        = etx_release,
       };
       ```
  3. Create IOCTL command in a userspace application
     ```
     #define WR_VALUE _IOW('a', 'a', int32_t*)
     #define RD_VALUE _IOR('a', 'b', int32_t*)
     ```
  4. Use IOCTL system call in userspace
     ```
     #include <sys/ioctl.h>
     ioctl(fd, WR_VALUE, (int32_t*)&number);
     ioctl(fd, RD_VALUE, (int32_t*)&value);
     ```
  - https://github.com/Embetronicx/Tutorials/tree/master/Linux/\
    Device_Driver/IOCTL
- procfs
- sysfs
- configfs
- debugfs
- sysctl
- udp sockets
- netlink sockets

## drivers
- dt: device tree or previosly called of(OpenFirmware)

### PCI: Peripheral Component Interconnect
- pci number: 00:02.01: bus:device.function
- rootComplex: device with only downStream port. 00.00.00
- bridge: device with both upStream and downStream port. connects 2 buses
- endPoint: device with only upStream port
- address spaces of pci device: configuration space, memoryOrIo space.
- ECAM(EnhancedConfigurationAccessMechanism)Address mapping:
  - |Bus(8bits)|Device(5)|Function(3)|Offset(12)|
- serial port data is sent over Io space. frames of gpu stored in memory space
- BAR: Base Address Registers, link between memoryOrIo and configuration space.
  It says: Whether its a memory or io space(bit0)
  - bits1,2: 00: 32bit 01: 64bit AddressDecoding
  - how much space is available on the bar(write1's clear 4lsbits of answer, negate, +1)
  - map virtual memory address space to bar

                PCI BAR Bits
+-------+----------------+---------------------------+
| Bits  | Description    | Values                    |
+=======+================+===========================+
|                 For all PCI BARs                   |
+-------+----------------+---------------------------+
| 0     | Region Type    | 0 = Memory                |
|       |                | 1 = I/O                   |
+-------+----------------+---------------------------+
|                 For Memory BARs                    |
+-------+----------------+---------------------------+
| 2-1   | Locatable      | 0 = any 32-bit            |
|       |                | 1 = < 1 MB                |
|       |                | 2 = any 64-bit            |
+-------+----------------+---------------------------+
| 3     | Prefetchable   | 0 = no                    |
|       |                | 1 = yes                   |
+-------+----------------+---------------------------+
| 31-4  | Base Address   | naturally 16-byte aligned |
+-------+----------------+---------------------------+
|                  For I/O BARs                      |
+-------+----------------+---------------------------+
| 1     | Reserved       |                           |
+-------+----------------+---------------------------+
| 31-2  | Base Address   | naturally 4-byte aligned  |
+-------+----------------+---------------------------+
- to compute available memory or io on pci device, write all 1's to BAR and
  read back from BAR, the read value contains
#### pci bus enumeration
- bus connected directly to cpu is always bus 0
- scans bus for devices
- `lspci -tv`: tree view
```
-[0000:00]-+-00.0  Intel Corporation Celeron N3350/Pentium N4200/Atom E3900 Series Host Bridge
           +-13.0-[01]--
           +-13.2-[02]----00.0  Realtek Semiconductor Co., Ltd. RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet Controller
$ lspci
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet Controller (rev 15)
```
- device 13 on bus 00 has 2 buses as functions
- 13.2 = PCI device 00:13.2 (a bridge/port on the host bridge)
- [02] = PCI bus 2 (created by that bridge)
- ---00.0 = Device 00:0 on bus 2 (the Realtek NIC)
- so the NIC pci addres is 02.00.0 because its on 2nd bus(among all the buses
  in the system) .00 device and .0 function.
```bash
$ lspci
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 500 (rev 0b)

$ ./pciheader 00 02 0
|    Byte 0    |   Byte 1     |    Byte 2    |    Byte 3    |
|-----------------------------------------------------------|
|          Vendor ID          |          Device ID          |
|            0x8086           |            0x5A85           |  0x00
|-----------------------------------------------------------|
|           Command           |           Status            |
|            0x0407           |            0x0010           |  0x04
|-----------------------------------------------------------|
| Revision ID  |                 Class Code                 |
|     0x0B     |                   0x000300                 |  0x08
|-----------------------------------------------------------|
| Cache Line S |  Lat. Timer  | Header Type  |     BIST     |
|     0x10     |     0x00     |     0x00     |     0x00     |  0x0c
|-----------------------------------------------------------|
|                           BAR 0                           |
|                          0x90000004                       |  0x10
|-----------------------------------------------------------|
|                           BAR 1                           |
|                          0x00000000                       |  0x14
|-----------------------------------------------------------|
|                           BAR 2                           |
|                          0x8000000C                       |  0x18
|-----------------------------------------------------------|
|                           BAR 3                           |
|                          0x00000000                       |  0x1c
|-----------------------------------------------------------|
|                           BAR 4                           |
|                          0x00002001                       |  0x20
|-----------------------------------------------------------|
|                           BAR 5                           |
|                          0x00000000                       |  0x24
|-----------------------------------------------------------|
|                    Cardbus CIS Pointer                    |
|                          0x00000000                       |  0x28
|-----------------------------------------------------------|
|     Subsystem Vendor ID     |        Subsystem ID         |
|            0x1025           |            0x110C           |  0x2c
|-----------------------------------------------------------|
|                   Expansion ROM Address                   |
|                          0x00000000                       |  0x30
|-----------------------------------------------------------|
| Cap. Pointer |                  Reserved                  |
|     0x40     |                   0x000000                 |  0x34
|-----------------------------------------------------------|
|                         Reserved                          |
|                          0x00000000                       |  0x38
|-----------------------------------------------------------|
|     IRQ      |   IRQ Pin    |   Min Gnt.   |   Max Lat.   |
|     0xFF     |     0x01     |     0x00     |     0x00     |  0x3c
|-----------------------------------------------------------|
```
- command: register with which host system can control pcie endpoint

### GPU
#### DRM
- provides MemoryManagement, InterruptHandling, DMA and uniform interface to
  applications.
- it features TTM memory manager, output configuration and mode setting,
  the new vblank internals
##### i915
- i915, drm_display_helper, drm_buddy, i2c_algo_bit, video, cec

### Thermal

## add --removable for virtual box
grub-install --target=x86_64-efi --efi-directory=/boot
vi /etc/default/grub
# you can also append custom menu entry in /etc/grub.d/40_custom
# you can copy existing menu entry from /boot/grub/grub.cfg and rename
grub-mkconfig -o /boot/grub/grub.cfg
vi /boot/grub/grub.cfg
...
menuentry ... {
...
linux /vmlinuz-4.19.66-gentoo root=/dev/sdb5 ro softlevel=vbox
}
emerge @module-rebuild

## UEFI as bootloader
```
emerge -av sys-boot/efibootmgr

efibootmgr --create --disk /dev/sdc --part 1 --label "Grub" --loader "\EFI\grub\grubx64.efi" -u "root=PARTUUID=b3ff8644-a7e4-ed42-b91a-3e5e5a560e11 cgroup_memory=1 cgroup_enable=cpuset cgroup_devices=1 cgroup_blkio=1 softlevel=xwin dobtrfs intel_iommu=on iommu=pt fbcon=rotate:3 module_blacklist=nvidia,nvidiafb vfio-pci.ids=10de:1f08,10de:10f9,10de:1ada,10de:1adb,c0a9:2263 default_hugepagesz=1G hugepagesz=1G hugepages=16 isolcpus=4-5 nohz_full=3-5 rcu_nocbs=3-5"

efibootmgr -c -d /dev/sda -p 1 -L "Gentoo" -l '\efi\boot\bootx64.efi' -u 'root=/dev/sda3 initrd=\efi\boot\initramfs.img quiet'

# delete and modify
efibootmgr -b 0002 -B

## for amdgpu rx7800
sudo efibootmgr -c -d /dev/sda3 -p 1 -L "Godavari" -l '\efi\Gentoo\vmlinuz-6.6.51-gentoo-dist.efi' -u 'root=/dev/sda3 amdgpu.dpm=1 softlevel=bsp initrd=\efi\Gentoo\initramfs-6.6.51-gentoo-dist.img amdgpu.ppfeaturemask=0x0007bfff'

## to reboot to UEFI
sudo bootctl reboot-to-firmware true
sudo
```

## autologin user /etc/inittab
```
c1:12345:respawn:/sbin/agetty --noclear --autologin Necktwi 38400 tty1 linux
```

## add nologin system user
useradd -rM puddle
usermod -L puddle
chage -M 1 doctor; # doctor's password expire in 1 day
chage -M

## rename user
```
exec sudo -i
killall -u [oldname]
id [oldname]
usermod -l [newname] [oldname]
groupmod -n [newname] [oldname]
usermod -d /home/[newname] -m [newname]
usermod -c "[full name (new)]" [newname]
id [newname]
```

## acl
getfacl
setfacl -m u:username:rwx /testfiles
setfacl -m g:groupname:rwx testfolder/
#append -d to set default acl

## find ssd serial numaber
udevadm info --query=all --name=/dev/sda | grep ID_SERIAL

## change default shell to bash
- `chsh /bin/bash` relogin

## ~/.bashrc
executed at the start of interactive non-login shell
# ~/.bash_profile
executed at the start of login shell

## delete bash variable
unset MY_VAR

## foreground a job
- `jobs`
- `fg %1`

## security
- Stack Smashing Protection

### set the shell properties example make it print all the commands
set -x
### unset
set +x

## print the shell name
echo $SHELL

## create coredump up on abort
- `ulimit -c unlimited`

# screen
# scroll
C-a ESC
ESC or q to end scroll
RET to select text
RET to copy text
C-a ] - to paste text
C-a c - new window
C-a C-a - switch to last active window
C-a '
C-a n - change to next window in list
C-a p - change to previous window in list
C-a " - window list
screen -S <session_name>
screen -D -R -S <session_name>

# set baud rate for a serial device
stty -F /dev/ttyUSB0 115200
# start dialog with serial device (telnet)
picocom -b 115200 -e p /dev/ttyUSB0
## quit picocom
`C-p C-q`

# print disk usage or file size in human readable format
du -h /var/log
# print sizes of only immediate files or folders
du -sh /mnt/root-rebound/*
# print disk usage
df -h

split -b 23k /var/tmp/portage/media-video/vlc-3.0.9999/temp/build.log build.log;fs=(build.log*);tot=${#fs[@]};i=0;for f in ${fs[@]}; do if [ $i -lt 3 ] || [ $i -gt $(( $tot - 3 )) ]; then wgetpaste -s dpaste $f; echo ""; fi; i=$(( $i + 1 )); done;rm -f build.log*

## print keys
- `showkey -s`

## change key map
- `setxkbmap -option altwin:swap_alt_win` swaps alt and super keys

## nano
- `M-w search next16`

## tmux
tmux ls
tmux a -t 1
C-a :kill-session
tmux kill-session -t 3
C-a q - kill window
tmux -L myname
tmux -L myname a
C-a d detach
C-a c - new window
C-a p - switch to previous w
C-a 1 - switch to 1 window
C-a [ - copy mode start
C-r - search up
C-s - search down
n - next
N - previous
C-space - toggle selecting text with arrows
M-w or C-w - copy
C-a ] - paste
C-a :swap-window -t 0
C-a :set -g status off
C-a % split vertically into panes
C-a " split horizontally
C-a o switch panes
C-a :resize-pane -U/D/L/R 10

### transfer program to tmux

### tmux.conf
#send prefix inside app; C-a a sends C-a inside app
bind-key a send-prefix
#for emacs
set -g default-terminal "tmux-256color"
#for 24bit color
set-option -a terminal-overrides ",*256col*:RGB"

## steam


## get terminfo
infocmp -x
infocmp tmux.xterm-256color
# add terminfo
tic -x /etc/terminfo/t/tmux-24Mcolor-italic.terminfo

## Check 256 color
printf "\x1b[38;5;165m256color\e[0m\n"
## Check true color
printf "\x1b[38;2;255;02;03mTRUECOLOR\x1b[0m\n"
## get background color
printf "\e]11;?\a"
## print ascii colors
```
RED=$(tput setaf 1)
GREEN=$(tput setaf 2)
YELLOW=$(tput setaf 3)
BLUE=$(tput setaf 4)
MAGENTA=$(tput setaf 5)
CYAN=$(tput setaf 6)
WHITE=$(tput setaf 7)
RESET=$(tput sgr0)
echo "${RED}This is red text.${RESET}"
echo "${GREEN}This is green text.${RESET}"
echo "${YELLOW}This is yellow text.${RESET}"
echo "${BLUE}This is blue text.${RESET}"
echo "${MAGENTA}This is magenta text.${RESET}"
echo "${CYAN}This is cyan text.${RESET}"
echo "${WHITE}This is white text.${RESET}"
```
## printf echo file
printf '%b\n' "$(cat my_file.txt)"

# leave current command in middle for another command and resume
C-u -leave
C-y -resume

# search command history
C-r

curl --request GET --header 'PRIVATE-TOKEN: ckHc9TVLdszJfwsFSYwS' 'https://gitlab.example.com/api/v4/projects/13083/repository/files/app%2Fmodels%2Fkey%2Erb?ref=master' -o Erb.txt

## measure time taken by a command
time <command>

# mount img
fdisk -l /mnt/Aren/software/common/genpi64.img
# get offset; if sectors muliply with sector size to get offset in bytes
sudo mount -o loop,offset=$((131072*512)),sizelimit=$((23068672*512)) /mnt/IceCap/software/common/genpi64.img /mnt/genpi64/
sudo mount -o loop,offset=$((2048*512)),sizelimit=$((129024*512)) /mnt/IceCap/software/common/genpi64.img /mnt/genpi64/boot/
losetup -d /dev/loop0
# create a loop device
mknod -m 0660 /dev/loop8 b 7 8

## ttyecho
https://www.humbug.in/2010/utility-to-send-commands-or-data-to-other-terminals-ttypts/

## send commands to another terminal tty
sudo ttyecho -n /dev/pts/0 "~/workspace/synergy-core/build/bin/synergyc -f --restart -n RPi3B 192.168.2.9"

# A real-time interactive pattern matcher in console that updates the tty input buffer.

# selector examples
selector -v -x @ <(find . -maxdepth 2 -type d | awk '{print $0"@cd "$0}')
selector -v -x @ <(grep -E -o 'http[^ ]+' fileWithURLS)

# Find current tty
tty
# to find tty associated with /dev/ttyUSB0
dmesg | grep tty

## view old dmesg
journalctl -o short-precise -k -b -1

## view dmesg in real time
dmesg -w

# list processes attached to a tty
ps -t /dev/tty1 -o comm=
# list all processes
ps -eaf
pstree
# list shared libraries to which the process is linked to
lsof -p <pid>

# change virtual tty
chvt

# get file owner
stat -c '%U' /path/of/file/or/directory

# suspend a shell
suspend
# suspend a chroot
suspend
kill -sigcont

## suspend and resume a process
kill -STOP <pid>
kill -CONT <pid>

## set process priority
- `renice <niceness> <pid>` lesser the niceness higher the priority

## wget saveas
wget https://lkml.org/lkml/diff/2018/12/11/1277/1 -O 2

### wget download folder
wget -r -np -R "index.html*" http://example.com/configs/.vim/

# nfs reload config
exportfs -ra
# nfs can't be mounted with username and password or try -O user=root,pass=mypass

# s & t sticky bits
s - makes files in the dir with its gid or executes files with their uid (setuid)
t - makes files in the dir deletable only by their owner
# to set stick bit on all the subfolders including current folder
sudo chmod g+s ./**/
# to set umask for a directory
sudo setfacl -d -m group:portage:rwx /var/db/repos/gentoo/**/

fallocate -l 1G /swapfile

mkfs.fat <device>
mkfs.vfat -F 32 <device>
mkfs.ext4 -L <label> <device>

sudo btrfs filesystem label /dev/sdb3 RPi3B
fatlabel /dev/device NEW_LABEL
mkswap /dev/device
swaplabel -L new_label /dev/device
swapon -s; #list mounted swap devices
e2label /dev/sda3 Linux #label ext fss
ntfslabel /dev/sda2 Windows

#repair ntfs volume
ntfsfix /dev/sda1

# to map users in ntfs drive to linux users
# first umount the ntfs drive /dev/sda1 if it is mounted
umount /dev/sda1
ntfsusermap /dev/sda1
# now give linux userid and groupid of prompted ntfs user
# now UserMapping file is created in the current directory
mount /dev/sda1 /mnt/IceCap
mkdir /mnt/IceCap/.NTFS-3G
mv UserMapping /mnt/IceCap/.NTFS-3G/

scp -o LogLevel=DEBUG -o Port=2222
sshd -p 2222 -dddd

PermitRootLogin yes #sshd_config to allow root login
ClientAliveCountMax 0

# all subfolders glob
shopt -s globstar
./**/*/

# /etc/modprobe.d/blacklist.conf
blacklist nvidia

# kernle commandline parameter
module_blacklist=nvidia,nvidiafb

# PAM
ls /lib/security
fgetpwent - returns passwd structure by parsing next line in /etc/passwd.
pam_modutil_getpwnam(pam_handle_t *pamh, const char *user)

# Check for /sys/firmware/efi for efi

# Parted
parted -a optimal /dev/sda mkpart primary 0% 10GB

# Debug files location
/usr/lib/debug

# chroot mount
mount /dev/sde3 /mnt/gentoo
mount /dev/sde1 /mnt/gentoo/boot
#mount /dev/sda1 /mnt/gentoo/mnt/IceCap
#mount --bind /mnt/gentoo/mnt/IceCap/src /mnt/gentoo/usr/src
#mount --bind /mnt/gentoo/mnt/IceCap/var/db/repos /mnt/gentoo/var/db/repos
#mount --bind /mnt/gentoo/mnt/IceCap/var/tmp /mnt/gentoo/var/tmp
#mount --bind /mnt/gentoo/mnt/IceCap/tmp /mnt/gentoo/tmp

mount --types proc /proc /mnt/gentoo/proc
mount --rbind /sys /mnt/gentoo/sys
mount --make-rslave /mnt/gentoo/sys
mount --rbind /dev /mnt/gentoo/dev
mount --make-rslave /mnt/gentoo/dev
mount --bind /run /mnt/gentoo/run
mount --make-slave /mnt/gentoo/run

cp --dereference /etc/resolv.conf /mnt/gentoo/etc/

chroot /mnt/gentoo /bin/bash
source /etc/profile
export PS1="(chroot) ${PS1}"

umount -R /mnt/gentoo/dev
umount -R /mnt/gentoo/sys
umount -R /mnt/gentoo/proc
umount -R /mnt/gentoo/run
umount -R /mnt/gentoo/dev
umount -R /mnt/gentoo/boot
umount -R /mnt/gentoo/

# Check folder format type
df -T /var/tmp/portage

# casesafe
filenames

## suspend to mem or sleep
echo mem > /sys/power/state

## suspend to disk or hibernate
echo disk > /sys/power/state

## remove power to a device
echo "D3cold" > /sys/devices/pci0000\:00/0000\:00\:01.0/0000\:01\:00.0/power_state
### it may also be done via
/sys/bus/acpi/devices/device\:0c/power/

## stop charging
`echo 1 > /sys/class/power_supply/battery/charge_disable`

# actual work done by shell
/lib/ld-linux.so.2 --library-path PATH EXECUTABLE

chown -h owner:group symlink

# find number of rows and columns in a terminal
tput lines
tput cols
# set number of rows
stty rows 50

## freeze or hang terminal
C-s
## unfreeze or unhang terminal
C-q

## list pci devices
lspci -vv
## lines start with busid e.g. 00:01.0

## get motherboard info
dmidecode -t 2

## list harddisc details
hdpaarm -I /dev/sda

## get BIOS, UEFI, CPU, hardware details
dmidecode

## get stack size in kb
ulimit -s

## to rice get cpu flags
```
emerge --ask --oneshot app-portage/cpuid2cpuflags
#core3566output: CPU_FLAGS_ARM: edsp neon neon-fp16 thumb vfp vfpv3 vfpv4
#vfp-d32 aes sha1 sha2 crc32 asimd asimddp asimdhp v4 v5 v6 v7 v8 thumb2
#if gcc, portage adds -mneon -medsp etc. to compiler
#llvm will auto optimize, based on 
cpuid2cpuflags 
echo "*/* $(cpuid2cpuflags)" > /etc/portage/package.use/00cpu-flags
emerge -av app-misc/resolve-march-native
resolve-march-native
```

# test automatic proxy pac files
pactester -p /usr/local/proxy.pac -u http://www.google.com

# activate 1GiB hugepages
default_hugepagesz=1G hugepagesz=1G hugepages=8
# transparent hugepages -
mkdir /dev/hugepages
mount -t hugetlbfs nodev /dev/hugepages

# wayland
# -------
weston - implementation of wayland compositor; implemented in C
by wayland project.
# check if wayland
echo $XDG_SESSION_TYPE
# force wayland
GDK_BACKEND=wayland gnome-terminal

# TransmissionBT
# --------------
pkill -HUP transmission-daemon
vi ~/.config/transmission-daemon/settings.json
or
rc-service transmission-daemon stop
vi /var/lib/transmission/config/settings.json
"rpc-whitelist": "127.0.0.1,192.168.100.*,192.168.0.*,192.168.2.*,::1",
http://192.168.100.3:9091

# Parse JSON
cmake -E capabilities | jq -r '.version.string'
#>3.21.1

## WakeOnLan
```
sudo emerge -av sys-apps/ethtool
sudo ethtool eno2 | grep -i wake
// -g: enable, -d: disable
sudo ethtool -s eno2 wol g
//```/etc/conf.d/net
ethtool_change_eno2="wol g"
//```
wakeonlan -i 192.168.2.255 70:85:c2:c5:95:d1
```

# wgetpaste to specified server
# -c '<command>'
wgetpaste -s dpaste /usr/src/linux/.config

# change uid or gid of files in a folder owned by a user
find ~/ -user 1000 -exec chown -h Necktwi {} \;
find ~/ -group 1000 -exec chgrp -h Necktwi {} \;

# meta - operations across OS
# ctrl - control the application
# alt - alterate the content opened by the application

## WiFi
/usr/sbin/iwconfig wlan0 essid Dumbledore key 41216f23306d6f7240
sudo wpa_supplicant -B -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf -D wext
sudo dhclient wlan0
### connect with nmcli
```
nmcli dev wifi list
sudo nmcli dev wifi connect <ssid> password "<password>"
```

## qemu

<feature policy="require" name="vmx-exit-load-pat"/>
<feature policy="require" name="vmx-exit-nosave-debugctl"/>
<feature policy="require" name="vmx-exit-save-efer"/>
<feature policy="require" name="vmx-exit-save-pat"/>
<feature policy="require" name="vmx-exit-save-preemption-timer"/>
<feature policy="require" name="vmx-flexpriority"/>
<feature policy="require" name="vmx-hlt-exit"/>
<feature policy="require" name="vmx-intr-exit"/>
<feature policy="require" name="vmx-invept"/>
<feature policy="require" name="vmx-invept-all-context"/>
<feature policy="require" name="vmx-invept-single-context"/>
<feature policy="require" name="vmx-invept-single-context-noglobals"/>
<feature policy="require" name="vmx-invlpg-exit"/>
<feature policy="require" name="vmx-invvpid-all-context"/>
<feature policy="require" name="vmx-invvpid-single-addr"/>
<feature policy="require" name="vmx-io-bitmap"/>
<feature policy="require" name="vmx-io-exit"/>
<feature policy="require" name="vmx-monitor-exit"/>
<feature policy="require" name="vmx-movdr-exit"/>
<feature policy="require" name="vmx-msr-bitmap"/>
<feature policy="require" name="vmx-mwait-exit"/>
<feature policy="require" name="vmx-nmi-exit"/>
<feature policy="require" name="vmx-page-walk-4"/>
<feature policy="require" name="vmx-pause-exit"/>
<feature policy="require" name="vmx-pml"/>
<feature policy="require" name="vmx-preemption-timer"/>
<feature policy="require" name="vmx-rdpmc-exit"/>
<feature policy="require" name="vmx-rdtsc-exit"/>
<feature policy="require" name="vmx-secondary-ctls"/>
<feature policy="require" name="vmx-shadow-vmcs"/>
<feature policy="require" name="vmx-store-lma"/>
<feature policy="require" name="vmx-true-ctls"/>
<feature policy="require" name="vmx-tsc-offset"/>
<feature policy="require" name="vmx-unrestricted-guest"/>
<feature policy="require" name="vmx-vintr-pending"/>
<feature policy="require" name="vmx-vmwrite-vmexit-fields"/>
<feature policy="require" name="vmx-vnmi"/>
<feature policy="require" name="vmx-vnmi-pending"/>
<feature policy="require" name="vmx-vpid"/>

<feature policy="require" name="sse4_1"/>
<feature policy="require" name="sse4_2"/>
### qemu bridge with ethernet or wifi

### libvirt to qemu
cat /var/log/libvirt/qemu/Win10.log

Exec=sh -c "rc-service libvirtd.x start >> /var/log/Win10.log 2>&1 || /usr/bin/virsh --connect qemu:///system start Win10 >> /var/log/Win10.log 2>&1 || /usr/bin/scream -m /dev/shm/scream-ivshmem >> /var/log/Win10.log 2>&1"

qemu-system-x86_64 -snapshot -m 3G -enable-kvm -usbdevice tablet -drive file=/dev/sda,if=virtio -drive file=/mnt/IceCap/software/common/Win10_1903_V1_English_x64.iso -drive file=/usr/share/drivers/windows/virtio-win-0.1.160.iso,media=cdrom -boot d -net none

sudo qemu-system-x86_64 --enable-kvm -cpu host -m 2048 -smp 3 -mem-path /dev/hugepages \
-display sdl -vga qxl \
-device qemu-xhci,id=xhci \
-device virtio-tablet,wheel-axis=true \
-soundhw hda \
-netdev user,id=vmnic,smb=/temp \
-device virtio-net,netdev=vmnic \
-drive file=/usr/share/edk2-ovmf/OVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on \
-drive file=$HOME/.config/qemu-windows.nvram,if=pflash,format=raw,unit=1 \
-drive file=/dev/sda,index=0,media=disk,driver=raw -cdrom /usr/share/edk2-ovmf/UefiShell.iso

```
sudo /usr/bin/qemu-system-x86_64 \
-name guest=Gentoo \
-drive file=/mnt/i/Gowtham/software/common/install-amd64-minimal-20190821T214502Z.iso,media=cdrom,readonly \
-blockdev '{"driver":"host_device","filename":"/dev/sdd","aio":"native","node-name":"libvirt-2-storage","cache":{"direct":true,"no-flush":false},"auto-read-only":true,"discard":"unmap"}' \
-net nic -net user \
--enable-kvm \
-m 4096 \
-vga qxl \
-smp 2,sockets=2,cores=1,threads=1 \
-cpu kvm64,+vmx,+vme,+msr,+x2apic,+hypervisor,+aes,+vmx-activity-hlt,+vmx-cr3-load-noexit,+vmx-cr3-store-noexit,+vmx-cr8-load-exit,+vmx-cr8-store-exit,+vmx-desc-exit,+vmx-entry-ia32e-mode,+vmx-entry-load-efer,+vmx-entry-load-pat,+vmx-entry-noload-debugctl,+vmx-ept,+vmx-ept-1gb,+vmx-ept-2mb,+vmx-ept-execonly,+vmx-eptad,+vmx-exit-ack-intr,+vmx-exit-load-efer,+vmx-exit-load-pat,+vmx-exit-nosave-debugctl,+vmx-exit-save-efer,+vmx-exit-save-pat,+vmx-exit-save-preemption-timer,+vmx-flexpriority,+vmx-hlt-exit,+vmx-intr-exit,+vmx-invept,+vmx-invept-all-context,+vmx-invept-single-context,+vmx-invept-single-context,+vmx-invept-single-context-noglobals,+vmx-invlpg-exit,+vmx-invvpid,+vmx-invvpid-all-context,+vmx-invvpid-single-addr,+vmx-io-bitmap,+vmx-io-exit,+vmx-monitor-exit,+vmx-movdr-exit,+vmx-msr-bitmap,+vmx-mwait-exit,+vmx-nmi-exit,+vmx-page-walk-4,+vmx-pause-exit,+vmx-pml,+vmx-preemption-timer,+vmx-rdpmc-exit,+vmx-rdtsc-exit,+vmx-secondary-ctls,+vmx-shadow-vmcs,+vmx-store-lma,+vmx-true-ctls,+vmx-tsc-offset,+vmx-unrestricted-guest,+vmx-vintr-pending,+vmx-vmwrite-vmexit-fields,+vmx-vnmi,+vmx-vnmi-pending,+vmx-vpid,+de,+pse,+tsc,+msr,+pae,+mce,+cx8,+apic,+sep,+mtrr,+pge,+mca,+cmov,+pat,+pse36,+clflush,+mmx,+fxsr,+sse,+sse2,+ss,+ht,+syscall,+nx,+pdpe1gb,+rdtscp,+lm,+pni,+pclmulqdq,+vmx,+ssse3,+fma,+cx16,+pcid,+sse4_1,+sse4_2,+movbe,+popcnt,+aes,+xsave,+avx,+f16c,+rdrand,+hypervisor,+lahf_lm,+abm,+3dnowprefetch,+ssbd,+ibpb,+stibp,+fsgsbase,+bmi1,+avx2,+smep,+bmi2,+erms,+invpcid,+rdseed,+adx,+smap,+clflushopt,+xsaveopt,+xsavec,+xgetbv1,+xsaves

sudo emerge -av virt-viewer spice-vdagent
qemu-img create -f vmdk -o compat6 /mnt/IceCap/Gowtham/virtual_machines/Ubuntu/Ubuntu.vmdk 1024G

qemu-img create -f qcow2 -o preallocation=metadata,lazy_refcounts=on /mnt/IceCap/Gowtham/virtual_machines/lubuntu/lubuntu.qcow2 64G

# for dynamic disk
#qemu-img create -f qcow2 -o preallocation=off Ubuntu.qcow2 64G

sudo /usr/bin/qemu-system-x86_64 -name guest=lubuntu --enable-kvm -m 16392 -drive file=/usr/share/edk2-ovmf/OVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on -drive file=/usr/share/edk2-ovmf/OVMF_VARS.fd,if=pflash,format=raw,unit=1 -drive file=/usr/share/edk2-ovmf/UefiShell.img,format=raw -drive file=/mnt/IceCap/Gowtham/virtual_machines/lubuntu/lubuntu.qcow2,if=virtio,cache=off -device qemu-xhci -usb -device usb-host,hostbus=1,hostaddr=2 -netdev bridge,id=hn0,br=br0 -device virtio-net-pci,netdev=hn0,id=nic1 -vga qxl -display spice-app,gl=on -spice rendernode=/dev/dri/by-path/pci-0000:00:02.0-render -boot menu=on

for g in /sys/kernel/iommu_groups/*; do echo "IOMMU Group ${g##*/}:"; for d in $g/devices/*; do echo -e "\t$(lspci -nns ${d##*/})"; done; done;

#(deprecated)sudo tunctl -t tap0 -g netdev
sudo ip tuntap add dev tap0 mode tap user $USER
sudo ifconfig tap0 192.168.11.1/24
sudo nano /etc/udev/rules.d/80_net_tun.rules
KERNEL=="tun", GROUP="netdev", MODE="0660", OPTIONS+="static_node=net/tun"
usermod -a -G netdev <user>
qemu-system-x86_64 -enable-kvm -m 4G -s -cpu host,vmx=on -name guest=ubuserv -drive file=~/workspace/Ubuntu.qcow2  -net nic,model=virtio -net tap,ifname=tap0,script=no,downscript=no
```

- https://wiki.archlinux.org/title/PCI_passthrough_via_OVMF#Passing_VM_audio_to_host_via_Scream

### problem with pci pass throughing ssd with smi sm2262 controller
https://bugzilla.kernel.org/show_bug.cgi?id=202055
# start input sharing with log file

### if pc.ram not found error, mount hugepages and
rc-service libvirtd restart

### qemu edit vm xml
virsh edit Win10

### mount qcow2
- install `qemu-utils`
```
sudo modprobe nbd max_part=8
sudo qemu-nbd --connect=/dev/nbd0 ~/example.[qcow2,vdi]
sudo mount /dev/nbd0p1 /mnt/imgmnt
sudo qemu-nbd --disconnect /dev/nbd0
```

### wakeup the suspended guest
sudo virsh dompmwakeup Win10
### send keys to qemu
sudo virsh
### wifi bridge
https://superuser.com/questions/694929/wireless-bridge-on-kvm-virtual-machine/1009881

### synergy
```
sudo apt install libx11-dev libxtst-dev libssl-dev\
    libgdk-pixbuf-2.0-dev libnotify-dev qtbase5-dev libxkbfile-dev cmake
# alpine linux
sudo apk add build-base libx11-dev libxtst-dev gdk-pixbuf-dev openssl-dev qt50-qtbase-dev libnotify-dev libxkbfile-dev cmake

cd ~/workspace/synergy-core/build
cmake -DBUILD_TESTS=OFF -DSYNERGY_BUILD_LEGACY_GUI=OFF -DBUILD_GUI=OFF -DSYNERGY_BUILD_LEGACY_INSTALLER=OFF ..
synergy-core --server -l /dev/null
./synergy-core --client --restart -f -n Blizlac 10.138.12.13
```
- scroll-lock key locks cursor to a computer

### add phydical disk
VirtManager->addHardware->storage->Select or create custom storage
->/dev/disk/by-id/ata-ST3500414CS_5VVN17ZK->DeviceType:DiskDevice
->BusType:SATA

## bluetooth id
## --------- --
#download psexec
#obtain the key from regedit only by running psexec -s -i regedit.exe
vi /var/lib/bluetooth/<Host BT MAC>/<BT MAC>
[Linkkey]
Key=<HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\BTHPORT\Parameters\Keys\<MAC>>
### list devices
```
bluetoothctl devices
bluetoothctl connect AC:B1:EE:87:C5:84
bluetoothctl diconnect AC:B1:EE:87:C5:84
```
### pair device
```
bluetoothclt
> scan on
> pair <MAC>
```

## fail2ban
```
[exim]
logpath = /var/log/exim/main.log
[dovecot]
logpath = /var/log/dovecot.log

# log file
tail -f /var/log/fail2ban.log
```

## openbox
### disable "the text file seems to be an executable script"
File manager-> Edit-> Preferences-> General-> Do not ask option on exe launch
call Xresources in /etc/xdg/openbox/environment

## kitty
#config location
~/.config/kitty/kitty.conf
#search kitty
C-S-h /<search_word>
#to transfer terminfo to remote device
kitty +kitten ssh remote
#tabs
New tab: ctrl + shift + t
Close tab: ctrl + shift + q
Next tab: ctrl + shift + right
Previous tab: ctrl + shift + left
#windows
New window: ctrl + shift + enter
Close window: ctrl + shift + w
Next window: ctrl + shift + ]
Previous window: ctrl + shift + [
Switch layout(vertical): C-S-l
Resize window: C-S-r
#set window title
kitty --title TM ssh 192.168.100.3

## gnome
## -----
/usr/local/share/applications/
update-desktop-database
### restart gnome-shell
Alt+F2
restart
### startup applications
.config/autostart/
### colord is daemon that installs and generates color profiles to accurately color manage input and output device.
gnome-terminal --window-with-profile=RPi3B
### version: activites->search->about
gtk-launch Synergy-client[.desktop]
### snap windows to edges of other windows while moving
hold Ctrl while moving the window
### Move/resize window using keyboard
Alt+F7/Alt+F8
### maximize
Alt+F10
### hide user from login screen
sudo vi /var/lib/AccountsService/users/gowtham
[User]
SystemAccount=true
### Disable overview on startup
DashToPanel>Behavior

## bspwm - binary space partitioning window manager
sudo emerge -av xorg-server bspwm sxkbd polybar dmenu firefox-bin
/usr/share/doc/bspwm-0.9.10/examples/bspwmrc
bspc node -i # create a receptacle
bspc node --presel-dir north -i # crate receptable in north to current window
bspc query -N -n .leaf # list all leaves
bspc query -N -n .leaf.\!window -d focused # list empty receptacle
-N: query nodes
-n: specify filter
-d: desktop selector
### insert current node into an empty node
bspc node $(bspc query -N -n focused) \
-n $(bspc query -N -n .leaf.\!window -d focused)
bspc node @/ -B # make all node sizes equal
## kill all empty nodes
for win in $(bspc query -N -n .leaf.\!window); do bspc node $win -k; done;
### restore layout
#j="$(bspc wm -d)"
#extract_canvas <<<"$j" >test.layout
#induce_rules <<<"$j" >test.rules
bspc wm -d > .config/bspwm/tiles4.json
/usr/share/doc/bspwm-0.9.10/examples/receptacles/extract_canvas .config/bspwm/tiles4.json > .config/bspwm/tiles4.layout
/usr/share/doc/bspwm-0.9.10/examples/receptacles/induce_rules .config/bspwm/tiles4.json > .config/bspwm/tiles4.rules
### to find name of window
xprop #and then click the desired window

## polybar

## dmenu
C-Y paste

## crontab
#to run a script at startup
crontab -e
@reboot sleep 100 && /usr/bin/sshfs 10.138.138.16:/mnt/ssd2 /home/amd/MI200-EthanolX/ &&  /sbin/ip addr | grep inet\ | tail -n1 | awk '{ print $2 }' | sed -nE 's/^(.+)\/.+/\1/p' > /home/amd/MI200-EthanolX/craterip

## firefox
firefox -p vpn
### remove scrollbars
~/.mozilla/firefox/8bupsft3.default-default/chrome/userChrome.css
~/.moonchild productions/pale moon/sc9dj3a1.default/chrome/userChrome.css

## exim
#check log
tail -f /var/log/exim/main.log
- fix all the issues in dovecot log
- ~/.maildir should be owned by Gowtham:mail and mail g+rwx
```
2023-09-05 20:12:50
1qdXGU-0003sE-1W <= bounce+8ca9d7.947b4-necktwi=ferryfair.com@mg.gitlab.com H=so254-136.mailgun.net [198.61.254.136] P=esmtps
X=TLS1.3:TLS_AES_128_GCM_SHA256:128 CV=no S=7733 DKIM=mg.gitlab.com id=64f73e6b19062_28a422c259c2@gitlab-sidekiq-catchall-v2-6ffb5c5c5c-d6g8c.mail]
```
- setup spf record as per https://mxtoolbox.com/dmarc/spf/setup/how-to-setup-or-modify-spf
- setup dkim record as per https://www.exim.org/exim-html-current/doc/html/spec_html/ch-dkim_spf_srs_and_dmarc.html and https://easydmarc.com/tools/dkim-record-generator
- remove failed messages from queue
```
# list mail queue
exim -bp
# delete a message from queue
exim -Mrm <msg-id>
```

## uptime
uptime

### exim4

## dovecot
tail -f /var/log/dovecot.log
- /etc/pam.d/smtp should exist

## logrotate
```
sudo crontab -e
0 12 * * * logrotate --verbose /etc/logrotate.conf
```
## /etc/sudoers
```
sudo visudo
Defaults        secure_path="<urPath>:/usr/local/sbin:\
/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
```

## gnome-network-displays
- runtime dependencies: nss-mdns, libsoup

## evolution mail client
### Receiving Email
server type: IMAP
server: FerryFair.com
port: 143
username: Necktwi
Encryption method: STARTTLS after connecting
Authentication: Password
### Sending Email
server type: SMTP
server: FerryFair.com
port: 25
server requires authentication: true
encryption method: STARTTLS after connecting
authentication: plain
username: Necktwi
### open profile folder
about:config

## command line copy text to clipboard
- `echo "hi" | xclip -selection clipboard`

## Parcellite clipboard history manager

# openrc
# ------
sysinit -> boot -> default -> shutdown
# inherit or stack runlevel
- `rc-update -s add default x`
# switch runlevel
- `sudo openrc default`
# print current runlevel
- `rc-status -r`

# dbus
# ----
# list of dbus services
dbus-send --session --dest=org.freedesktop.DBus --type=method_call --print-reply /org/freedesktop/DBus org.freedesktop.DBus.ListNames

# get kernel cmdline parameters or options
cat /proc/cmdline
watch lscpu

## ipv6

## disable ipv6
echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
### or in /etc/sysctl.conf, add
net.ipv6.conf.all.disable_ipv6=1
net.ipv6.conf.default.disable_ipv6=1

### display routes
route -A inet6 |grep -w "eth0"
ip -6 route show dev eth0

### open ipv6 website
http://[1080:0:0:0:8:800:200C:417A]:8888/index.html

## find window title, size, etc.
`xwininfo`
- and then click on the window whose name you want
`bspc query -N -n .window`
- prints windows id when bspwm used
`xprop -id <window_id>`
- prints window's class name instance name etc.

## relocate or resize windows
wmctrl -e g,x,y,w,h -r "<window title substring>"
wmctrl -l -G -x

# vfio
modprobe vfio_pci ids=10de:1f08,10de:10f9,10de:1ada,10de:1adb
modprobe vfio
modprobe vfio_iommu
modprobe vfio_virqfd
# to unload nvidia at runtime
sudo rc-service xdm stop
modprobe -r nvidia

## usb
- https://marc.info/?l=linux-usb&m=121459435621262&w=2
```
lsusb -t
#Bus#  4
#-Dev#   1 Vendor 0x1d6b Product 0x0001
#-Dev#   3 Vendor 0x046b Product 0xff10
sudo ./usbreset /dev/bus/usb/004/003
sudo cat /sys/kernel/debug/usb/devices
// to find major number
cat /sys/bus/usb/devices/1-5/idVendor
```

## thunderbolt

## musl
- no working browser with llvm musl

# QNX
PPS - Presistent Publish/Subscribe

## Puppy Linux

## Arch linux

### pacman
- to remove package and all its dependencies, `pacman -Rsc amdgpu-experimental`

## manjaro
### kde
#### panel
- ~/.config/plasmashellrc
- `kquitapp5 plasmashell && kstart5 plasmashell`

### turn off display
```
sleep 1 && xset dpms force off
```

## Core3566
### sdk
```
mkdir -p ~/proj/rk356x_linux_release_v1.3.0b_20221213
cd ~/proj/rk356x_linux_release_v1.3.0b_20221213
repo init --no-repo-verify -u https://gitlab.com/firefly-linux/manifests.git -b master -m rk356x_linux_release.xml --depth=1
sudo emerge -av expect patchelf app-admin/chrpath sys-apps/gawk sys-apps/texinfo dev-util/diffstat sys-fs/binfmt-support cmake bison flex unzip sys-apps/dtc dev-python/pyelftools
RK_ROOTFS_SYSTEM=gentoo ./build.sh
```

## Raspberrypi RPi3B
- use raspi-config to enable

### mhs35
```
cd ~/workspace/
git clone --depth=1 https://github.com/goodtft/LCD-show.git
cd LCD-show
sudo ./MHS35-show 180
sudo tee /etc/X11/xorg.conf.d/99-fbdev.conf > /dev/null <<EOF
Section "Device"
    Identifier "Framebuffer"
    Driver "fbdev"
EndSection
Section "Screen"
    Identifier "Default Screen"
    Device "Framebuffer"
    Monitor "Configured Monitor"
EndSection
EOF
sudo ./MHS35-show 180
sudo systemctl set-default graphical.target
sed -i 's/LXDE-pi/LXDE/' /etc/lightdm/lightdm.conf
sudo reboot
```

## i2c
- `sudo i2cdetect -y 1` 1 is i2c bus number

## Pixel3a Ubuntu unity
-