Linux cheat sheet

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These tips seem to work with Raspbian and in some cases Ubuntu.

Run a process beyond an SSH session

Useful for SSH’n into a machine and then starting a process and being able to close the session without killing the job. Also useful for running multiple programs in one ssh session.

Install screen if you haven’t already

   sudo apt-get install screen -y

Run screen on the server and use -S flag to give the session a name.

   screen -S myjob

Log in via ssh from the remote machine and use the -x flag to attach to that session

   screen -x myjob

Press ctl-a and then ctl-d to switch back without closing, or issue the command

   exit

to close the screen session.

Run a program on a remote display

When you run graphical programs over SSH the server will often throw errors about no screen being present. You need to put the display you want have the program to display to in your environment. You can do this by first runing “w” to see connected displays and then:

Run export to bring the proper display into your environment.

   export DISPLAY=:0

Run your program.

   python samplepythoncode.py

Quickly determine Pi CPU temperature

Run the following command in terminal.

   /opt/vc/bin/vcgencmd measure_temp

Set up wifi on a Pi with simple file

Create a file called “wpa_supplicant.conf” with the following content and place at root of “boot”

   network={
   ssid="SSID Name"
   psk="Password"
   key_mgmt=WPA-PSK
   }

Run Process At Startup

   crontab -e
   @reboot sleep 60;export DISPLAY=:0 && export XAUTHORITY=/home/user/.Xauthority && cd /home/pi/picorder/ && python picorder.py


Swap Keyboard Key

   xmodmap -e "keycode 94 = Shift_L"