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--- linux [2019/02/24 02:02]
127.0.0.1 external edit
+++ linux [2019/12/28 23:23] (current)
@@ Line 1: / Line 1: @@
 ====== Linux ======
-Linux is a beautiful example of clean engineering. Form follows function. The
+Linux is a beautiful example of clean engineering. Form follows function and
-following is a collection of notes.
+function follows coherent thoughts. The following is a collection of notes.
+===== Adding passwordless users =====
+To add a sudo user that doesn't have a password you have to first add a user with a password, and then delete the password. This activates the password.
+<code bash>
+sudo adduser usernameyoulike
+# give the user any temp password
+# the following command removes the password
+sudo passwd -d usernameyoulike
+# add the user to the sudoers list
+usermod -aG sudo usernameyoulike
+</code>
 ===== udev =====
-I fell in a deep rabbit hole with udev whilst building Primo. Here is a
+I fell in a deep rabbit hole with ''%%udev%%'' whilst building Primo. Here is a
-[[http://www.reactivated.net/writing_udev_rules.html|comprehensive guide about
+comprehensive guide about ''%%udev%%'' [[http://www.reactivated.net/writing_udev_rules.html|link]].
-this]].
-To get all the information about a usb device:
+To get all the information about a USB device:
 <code bash>
@@ Line 18: / Line 30: @@
 Some commands have changed since the bible has been written.
-To test, you can use the test function of udevadm. Problem is that you have to give
+To test, you can use the test function of ''%%udevadm%%''. Problem is that you have to give
-it the top level device path in sysfs. For example, an arduino plugged into
+it the top level device path in ''%%sysfs%%''. For example, an arduino plugged into
-Primo and showing up as ttyACM1, this was /sys/bus/usb/devices/1-6. To find the
+Primo and showing up as ''%%ttyACM1%%'', this was
-top level device path, use the command above and susbitute in the port name.
+''%%/sys/bus/usb/devices/1-6%%''. To find the top level device path, use the
+command above and substitute in the port name.
-To test an arduino:
+To test an Arduino:
 <code bash>
 udevadm test /sys/bus/usb/devices/1-6
 </code>
-To restart the udev system:
+To restart the ''%%udev%%'' system:
 <code bash>
 sudo udevadm control --reload-rules && udevadm trigger
@@ Line 35: / Line 48: @@
 You will still need to unplug/replug stuff!! Or do a reboot.
-Some pittfalls I came accross. You cannot change device names! You can only add
+Some pitfalls I came across. You cannot change device names! You can only add
-symlinks to them. The symlink did not work for the tara uvc_camera. I think this is
+symlinks to them. The symlink did not work for the Tara uvc_camera. I think this is
-issue has to do with the fact that the tara has some weird shit with the way the
+issue has to do with the fact that the Tara has some weird shit with the way the
 USB host onboard handles the two cameras.
+Here's some other commands:
+Lists the possible device attribute keys and their values along with the
+parents of the device.
+<code bash>
+udevadm info --attribute-walk /dev/bus/usb/<bus_num>/<device_num>
+</code>
+Lists the device attributes and their values.
+<code bash>
+udevadm info -a /dev/video0
+</code>
+Reload udev rules
+<code bash>
+udevadm control --reload-rules && udevadm trigger
+</code>
 ==== USB Information ====
-To get info on hidraw devices:
+To get info on ''%%hidraw%%'' devices:
 <code bash>
@@ Line 59: / Line 91: @@
 </code>
-When doing lsusb, use sudo!! If you don't, you won't be able to see devices whose
+When doing ''%%lsusb%%'', use ''%%sudo%%''!! If you don't, you won't be able to see devices whose
 permissions haven't been properly set.
+Shows the USB version of the devices with that vendor id:
+<code bash>
+sudo lsusb -v | grep 2560 -A 10 | grep bcdUSB
+</code>
 ===== cron =====
@@ Line 109: / Line 146: @@
 ==== Terminal ====
-I use the xfce4-terminal. I have all nicely setup with a config file that resides in ~/.config/xfce4/terminal
+I use the ''%%xfce4-terminal%%''. I have all nicely setup with a config file
+that resides in ''%%~/.config/xfce4/terminal%%''.
 ===== Moving Windows =====
@@ Line 153: / Line 191: @@
 xubuntu (xfce) desktop.
-using the x11 VNC server on the server. Port 5900 and 5901
+using the x11 VNC server on the server. Port 5900 and 5901.
 Running into security issues with the VNC server stuff. Tried:
@@ Line 185: / Line 223: @@
 Problem is that it is slow. I don't think there is anything we can do it. It is also
-slow through the lan. I've attributed this issue to running headless.
+slow through the LAN. I've attributed this issue to running headless.
 ===== Headless Operation =====
@@ Line 238: / Line 276: @@
   * . (dot command) same as source. This executes a list of commands. That is all.
   * use ssh -X if you want to ssh with an X server
+To remove all files except for one in ''%%zsh%%'':
+<code bash>
+setopt extendedglob
+rm -- ^file.txt
+</code>
 ==== Clipboard =====
@@ Line 245: / Line 290: @@
 sudo apt install xclip
 cat file | xclip -selection clipboard
+</code>
+====== Window File Subsystem for Linux ======
+This thing is awesome!
+For setting up ssh keys, xclip doesn't work. Use the following:
+<code bash>
+clip.exe < ~/.ssh/id_rsa.pub
+</code>
+===== SSH Access =====
+For setting up external ssh access I did the following:
+Reinstall openssh for some reason:
+<code bash>
+sudo apt-get purge openssh-server
+sudo apt-get install openssh-server
+</code>
+From an elevated powershell I ran this to change the port to 2222 to not
+interfere with any windows services:
+<code bash>
+New-NetFirewallRule -DisplayName "Allow Inbound Port 2222" -Direction Inbound -LocalPort 2222 -Protocol TCP -Action Allow
+</code>
+I added the following to sshd_config:
+<code bash>
+Port 2222
+PermitRootLogin no
+AllowUsers paul
+</code>
+I created an authorized hosts file and imported the keys.
+I tested the connection by running this on the server:
+<code bash>
+sudo service ssh stop
+sudo /usr/sbin/sshd -d
+</code>
+Then on the client I ran a debug version of an ssh server to see if I was
+receiving incoming connections.
+<code bash>
+ssh name@server -p 2222
+</code>
+I then monitored the server and make sure I could see the connection. The debug
+client quit out cause it didn't have correct paths to the keys, but the test was
+a success cause it validated the port pass through. I then restarted the regular
+service like this:
+<code bash>
+sudo service ssh start
 </code>