====== Linux ======
https://wiki.debian.org/NetworkConfiguration

https://wiki.debian.org/InstallingDebianOn/Allwinner

  * [[Kernel]]
  * [[ubuntu18.4]] [[ubuntu20.4]]
  * [[LXC]]
  * [[Docker]]
  * [[virtualbox]]
  * [[GIMP]]
  * [[multimedia]]
  * [[wifi]]
===== Preferences =====
==== Titlebar-Icons ====

  gsettings set org.gnome.desktop.wm.preferences button-layout ':minimize,maximize,close'
==== Terminal-Width ====
  stty rows 50 cols 150

if linebreak does not work this can help in ~/.bashrc:

  shopt -s checkwinsize
  #if [ $(tty) == '/dev/ttyS0' ]; then
  #  trap resize DEBUG
  #fi
  #resize-befehl in xterm
  export PROMPT_COMMAND="resize &>/dev/null ; $PROMPT_COMMAND"
===== ppp ifup-script =====

Script in /etc/ppp/ip-up.d must not have extension [[https://unix.stackexchange.com/questions/208343/vpn-script-at-etc-ppp-ip-up-d-not-autoexecuting-on-pptp-connection-establishe|Quelle]]

example: ppp-default-route in separate routing-Table:
<code>
PPP_LOCAL=$4
PPP_REMOTE=$5
PPP_IFACE=$1

ip route flush table telekom
ip route add $PPP_REMOTE/32 dev $PPP_IFACE src $PPP_LOCAL table telekom
ip route add default dev $PPP_IFACE table telekom
ip route show table telekom
exit 0
</code>
===== apt-get force ipv4 =====

  apt-get -o Acquire::ForceIPv4=true update

[[https://www.vultr.com/docs/force-apt-get-to-ipv4-or-ipv6-on-ubuntu-or-debian|Quelle]]

permanent (as root):

  echo 'Acquire::ForceIPv4 "true";' > /etc/apt/apt.conf.d/99force-ipv4

[[https://unix.stackexchange.com/a/100887|Quelle]]
===== basic x-server =====

  apt-get install --no-install-recommends xserver-xorg xinit openbox policykit-1 xterm xfonts-base

===== simple Mailserver =====

as Relay-Server (sending Mails over external Mailserver) for System-purposes (infos, backup,...)

https://linuxundich.de/gnu-linux/system-mails-ohne-einen-mail-server-mit-ssmtp-verschicken/

===== screen =====
http://fractio.nl/2008/09/29/setting-session-name-in-screen/

  screen -S Sessionname command

===== wget =====


-P download in dir

  wget <file.ext> -P /path/to/folder

-O download as file

  wget <file.ext> -O /path/to/folder/file.ext


===== processinfo =====

  ps -o pid,args -C tcpdump

===== ls =====

full timestamps:

  ls -l --time-style="+%Y-%m-%d %H:%M"

deactivate colors:

  ls -l --color=none

===== bashrc / alias =====

  alias cp="rsync -av --partial --progress"
  alias pynano="nano -ET4"
  alias catconf='find . -type f -exec grep -Iq . {} \; -printf "\n\n%p:\n" -exec cat {} \;'
===== nano =====

Jump to line: Ctrl+Shift+- (Ctrl+_)

Replace: Alt+R

==== settings ====

  sudo nano /etc/nanorc

=== Cursorposition ===

  ## Constantly display the cursor position in the status bar.  Note that
  ## this overrides "quickblank".
  set constantshow #temporär strg+C, 


=== linenumbers ===

  ## Display line numbers to the left of the text.
  set linenumbers  # alt+# to disable temporarily

=== TAB-width ===

  #/etc/nanorc
  set tabsize 4
  #temporary setting it (e.g. for Patches)
  nano -T 8 datei
====== storage check ======

  #filesystem:
  sudo fsck -f /dev/sdb1
  #check for bad sectors
  sudo badblocks -nsv /dev/sdb

http://www.das-werkstatt.com/forum/werkstatt/viewtopic.php?t=2346
====== NTP ======

  apt-get install ntp
  #nano /etc/ntp.conf # need restart after change
  service ntp status
  #show state of servers
  ntpq -p

manual update:

  service ntp stop
  ntpdate ptbtime1.ptb.de
  service ntp start

====== set time ======

  #timedatectl --help
  timedatectl set-timezone CET #timezone (CET/CEST)
  date -s "2020-10-29 19:14" #time
  hwclock -w #set RTC if there is any, else time will be wrong after next reboot
====== update-alternatives ======

  sudo apt-get install gcc-8-arm-linux-gnueabihf
  sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-gcc arm-linux-gnueabihf-gcc /usr/bin/arm-linux-gnueabihf-gcc-8 50
  sudo update-alternatives --config arm-linux-gnueabihf-gcc
  arm-linux-gnueabihf-gcc --version

  #to create update-alternatives in a loop you can use this
  for i in $(ls /usr/bin/arm-linux-gnueabihf-gcc-{9..12});do sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-gcc arm-linux-gnueabihf-gcc $i 50;done

other example

  sudo update-alternatives --install /usr/bin/calc calc /usr/bin/gnome-calculator 10
====== renaming ======

File test will be renamed into test.bak (same directory)

  mv /home/frank/test{,.bak}

====== gunzip ======

on-the-fly decompress and write to disk

  gunzip -c bpi-r3_sdmmc_bullseye.img.gz | sudo dd bs=1M status=progress conv=notrunc,fsync of=/dev/sdX

====== tar ======

  tar -xzf file.tar.gz --strip-components 1 -C DESTINATION

====== sed ======

extract text between patterns:

https://stackoverflow.com/questions/38972736/how-to-print-lines-between-two-patterns-inclusive-or-exclusive-in-sed-awk-or

example (extract frequencies from iw command):

  iw list | sed -n '/Frequencies/,/Band\|Supported commands/{/Band\|Supported commands/!p;}'
====== irssi ======

===== config =====

Server+nick:

  irssi -n NICK #start irssi with nickname

  /network add -nick NICK -autosendcmd "/msg nickserv IDENTIFY *******" fn
  /server add -auto -ssl -network fn chat.freenode.net 7070 #ports 6697, 7000 and 7070 for SSL-encrypted connections.

  /SET nick xxx
  /SET alternate_nick xxx
  
  /nick alternatenick
  /msg NickServ IDENTIFY mainnick password
  /msg NickServ GROUP

https://freenode.net/kb/answer/registration

  /alias nick_recover msg NickServ GHOST $0 $1; wait 2000; msg NickServ RELEASE $0 $1; wait 2000; nick $0; wait 2000; msg NickServ IDENTIFY $1
  /network modify -autosendcmd "/nick_recover NICK PASSWORD" fn
  /SET server_reconnect_time 300

https://irssi.org/documentation/startup/
===== switch windows =====

  /window 1-x #1=server-window

Ctrl+P (previous)/ctrl+N (next)

  /win list #shows open windows in the Server-Status (1)

===== Away mode =====

  /away grund #start awaymode (Nachrichten shown in Server-window #1)
  /away #stop away mode


====== udev ======

same serial-adapter with Symlink based on USB-Ports (behind Hub)

https://askubuntu.com/questions/49910/how-to-distinguish-between-identical-usb-to-serial-adapters

  udevadm info --attribute-walk --path=/sys/bus/usb-serial/devices/ttyUSB0

/etc/udev/rules.d/11-ttyusb.rules:
<code>
#r2 (first port) roothub-port.hubport
#    KERNELS=="1-3.1:1.0"
#    KERNELS=="1-3.1"
#r64 (second port=3)
#    KERNELS=="1-3.3:1.0"
#    KERNELS=="1-3.3"
KERNEL=="ttyUSB*", KERNELS=="*-*.1*", SYMLINK+="ttyUSB_R2"
KERNEL=="ttyUSB*", KERNELS=="*-*.3*", SYMLINK+="ttyUSB_R64"
</code>

my current config splitting by serial
<code>
#ch340 KERNELS=="1-3.3" no serial
SUBSYSTEM=="tty", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="7523", SYMLINK+="tty_r2pro"
#cp2102 KERNELS=="1-3.2"
SUBSYSTEM=="tty", ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="ea60", ATTRS{serial}=="010CB6FA", SYMLINK+="tty_r3"
#cp2104 KERNELS=="1-3.1"
SUBSYSTEM=="tty", ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="ea60", ATTRS{serial}=="0001", SYMLINK+="tty_r2"
</code>

this udev rules i use for ftdi 4xuart adapter (FT4232H Quad RS232-HS)
<code>
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6011", ENV{ID_USB_INTERFACE_NUM}=="00", SYMLINK+="ftdi_r2"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6011", ENV{ID_USB_INTERFACE_NUM}=="01", SYMLINK+="ftdi_r64"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6011", ENV{ID_USB_INTERFACE_NUM}=="02", SYMLINK+="ftdi_r3"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6011", ENV{ID_USB_INTERFACE_NUM}=="03", SYMLINK+="ftdi_r4"
</code>

easier way to get the main-properties of a device

  udevadm info /dev/sdb1
====== sshd ======
===== qnap (entware) =====

  nano /opt/etc/ssh/sshd_config #ggf. optionen anpassen (hostkey ecdsa/ed.../...)
  ps | grep ssh
  kill PID #PID= pid von /opt/sbin/sshd
  /opt/sbin/sshd -E /tmp/sshd.log -o LogLevel=DEBUG3
  tail -f /tmp/sshd.log
  #bei Fehler "Bad ownership":
  chmod go-w ~/;chmod 700 ~/.ssh;chmod 600 ~/.ssh/authorized_keys
  #wenn fertig
  /opt/etc/init.d/S40sshd restart

====== kernel kernelconfig (/proc/config.gz) ======

<code>
# modprobe configs
# zcat /proc/config.gz | grep -i hwmon
CONFIG_HWMON=y
# CONFIG_HWMON_DEBUG_CHIP is not set
# CONFIG_SENSORS_IIO_HWMON is not set
CONFIG_THERMAL_HWMON=y
</code>
====== mv-alternative ======

  rsync -avh --progress --remove-source-files source target/
  #delete empty directories (not done by rsync)
  find source/ -type d -empty -delete

====== other ======
===== force fsck =====

in kernel-cmdline:

  fsck.mode=force

===== smartctl / hdparm =====

<code>
smartctl -t short /dev/sdb
smartctl -a /dev/sdb | grep -A1 "Self-test execution status"
#Beispielausgabe:
Self-test execution status:      ( 249)	Self-test routine in progress...
					90% of test remaining.
#oder:
Self-test execution status:      ( 121)	The previous self-test completed having
					the read element of the test failed.

#warten bis fertig und bei Fehler:
smartctl -a /dev/sdb | grep '^#'
Beispielausgabe mit Fehler (long):
# 1  Extended offline    Completed: read failure       90%       267         1709921

#sektor und angrenzende in Schleife versuchen neu zu schreiben
for i in {1709920..1709930};do hdparm --yes-i-know-what-i-am-doing --repair-sector $i /dev/sdb;sleep 1;done
</code>

===== iostat =====

  apt install sysstat
  
Ausgabe:

<code>$ iostat -m -p /dev/sdb
Linux 5.15.0-56-generic (frank-G5) 	29.12.2022 	_x86_64_	(12 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           2,19    0,01    0,74    2,58    0,00   94,48

Device             tps    MB_read/s    MB_wrtn/s    MB_dscd/s    MB_read    MB_wrtn    MB_dscd
sdb               5,80         0,00         0,67         0,00          3       9123          0
sdb1              0,01         0,00         0,00         0,00          2          0          0
</code>
===== rc.local =====

https://www.troublenow.org/752/debian-10-add-rc-local/

===== VNC-Server =====

based on https://www.scivision.dev/vncserver-setup-on-ubuntu/

  apt install tightvncserver openbox
  apt install lxterminal firefox-esr --no-install-recommends

~/.vnc/xstartup
<code>
#!/bin/sh
xrdb $HOME/.Xresources
xsetroot -solid grey

unset SESSION_MANAGER
exec openbox-session &
</code>

~/startVNC.sh
<code>
#!/bin/sh
vncserver :1 -geometry 1024x768 -depth 8
</code>

do not forget to set execute rights

  chmod +x ~/startVNC.sh ~/.vnc/xstartup

i setart the script with rc.local (see above), but a init-script is also possible

https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-vnc-on-ubuntu-18-04-de

===== locales =====

  /usr/bin/locale: Cannot set LC_ALL to default locale: No such file or directory

Solution:

if not yet done, generate locales

  locale-gen de_DE.UTF-8

add this to /etc/environment:

  LC_ALL=de_DE.UTF-8
  LANG=de_DE.UTF-8

maybe again

  dpkg-reconfigure locales

now error should be fixed

  locale -a

Solution using /etc/default/locale was not working for me

===== LVM =====
https://wiki.debian.org/LVM#Create_a_PV

prepared initrd
<code>
  apt install initramfs-tools
  kernelversion=$(uname -r)
  echo $kernelversion
  zcat /proc/config.gz > /boot/config-$kernelversion
  less /boot/config-$kernelversion
  update-initramfs -k $kernelversion -c
</code>

<code>
root@bpi-r3-mini:~# apt install lvm2
root@bpi-r3-mini:~# fdisk /dev/nvme0n1
#changed type of partition 3 to lvm
root@bpi-r3-mini:~# pvcreate /dev/nvme0n1p3
root@bpi-r3-mini:~# vgcreate vg-nvme /dev/nvme0n1p3                             
  Volume group "vg-nvme" successfully created
root@bpi-r3-mini:~# vgdisplay
  --- Volume group ---
  VG Name               vg-nvme
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               80.74 GiB                                               
  PE Size               4.00 MiB                                                
  Total PE              20670                                                   
  Alloc PE / Size       0 / 0                                                   
  Free  PE / Size       20670 / 80.74 GiB                                       
  VG UUID               w22Wdx-Fhch-YNsA-roWh-Zq81-qv0R-d5fnvw                  
                                                                                
root@bpi-r3-mini:~# lvcreate -n var -L 10g vg-nvme                              
  Logical volume "var" created.
root@bpi-r3-mini:~# mkfs -t ext4 /dev/vg-nvme/var
root@bpi-r3-mini:~# mount /dev/mapper/vg--nvme-var /var_lvm
[ 5279.856899] EXT4-fs (dm-0): mounted filesystem 520d434d-fdfc-48f3-823d-77e602
7e84e7 r/w with ordered data mode. Quota mode: disabled.
root@bpi-r3-mini:~#
</code>