Linux & Python for Raspberry Pi: Getting started with Linux & Python

Learn to create inventive programs on your powerful Raspberry Pi and Linux & Python―with no programming experience required. This practical book has been revised to fully cover the new Raspberry Pi 3, including upgrades to the raspbian operating system. Discover how to configure hardware and software, write Linux & Python scripts, create user-friendly GUIs, and control external electronics. DIY projects include a digital output – LED RBG, Relay. Digital input –swich up/down or sensor LDR. Analog output servo motor controller. Build Internet of Thing (IoT) applications. Open sourch computer vision (OpenCV) with camera sense motion, image face/eye detecting. * Set up your Raspberry Pi and explore its features * Linux basic with command syntax, Linux file & directory command, standard I/O, file permission, file system and link * Linux shell scripting, VI Editor, Shell programming, process and system innitialization, user, utilities & APT * Python basic with syntax, data structure, function module, class, file I/O, thread, networking * Control dive with python web programing, HTTP, flask, web socket * Using python to drive hard ware GPIO, digital output, digital input, analog output – PWM, analog input – RC Circuit, high level sensor modules * Building raspberry-pi communication, serial, UART, I2C, SPI, bluetooth, BLE-Beacon * Raspberry-Pi Multimedia, buzzer, audio, camera, CCTV, computer vison with open CV face /eye detecting * Add powerful Web IoT with GPIO and camera web streaming * Set up your Arduino and developing environment, digital I/O, analog I/O control circuit 1. Installation 1.1 Introduction 1.2 Os(Rasbian) Installtion 1.3 Development Environment 2. Linux Basic 2.1 Introduction to Unix & Linux 2.2 Linux Command Syntax 3. Linux File System 3.1 File & Directory Command 3.2 Standard I/O 3.3 File Permission 3.4 File System and Link 4. Shell Scripting 4.1 VI Editor 4.2 Shell programming 5. Process & System 5.1 Process 5.2 System Initialization 5.3 User 5.4 Utilities & APT 6. Python Basic 6.1 Introduction 6.2 Syntax 6.3 Data Structure 6.4 Function 6.5 Module 6.6 Class 6.7 Exception 6.8 File I/O 6.9 Thread 6.10 Networking 7. Python Web Programming 7.1 Introduction 7.2 HTTP 7.3 Flask 7.4 WebSocket Chapter2: Raspberry-Pi for Prototyping 1. Raspberry-Pi & GPIO 1.1. GPIO 1.2. Digital Output 1.3. Digital Input 1.4. Analog Output – PWM 1.5. Analog Input – RC Circuit 1.6. High Level Sensor Modules 2. Raspberry-Pi Communication 2.1 Serial Communication 2.1 UART 2.1 I 2 C 2.1 SPI 2.1 Bluetooth 2.1 BLE - Beacon 3. Raspberry-Pi Multimedia 3.1 Buzzer 3.2 Audio 3.3 Camera 3.4 CCTV 3.5 OpenCV Computer Vision 8. Raspberry-Pi Web IoT 8.1 Introduction 8.2 Web with GPIO 8.3 Camera Web Streaming 9. Appendix 9.1 Arduino  Raspberry-Pi  https://en.wikipedia.org/wiki/Raspberry_Pi  Eben Upton, UK Raspberry Pi Foundation Founder  For teaching computer science in developing countries  2011, Alpha board  2012, First sales  Broadcom BCM2835 SoC  Designed as a PC, Not a development board  Raspberry Pi Boards Series  https://www.raspberrypi.org/products/  Raspberry Pi Boards Series  Raspberry Pi 3  ARMv8 CPU 1.2GHz 64bit quad-core  802.11n Wireless LAN  Bluetooth 4.1  Bluetooth Low Energy(BLE)  1GB RAM  4 USB ports  40 GPIO Pins  Full HDMI port  Ethernet port  3.5mm audio  Camera interface(CSI)  Display interface(DSI)  Micro SD card slot  VideoCore IV 3D graphics core  Raspberry Pi 3  OS image file download  https://www.raspberrypi.org/downloads/raspbian/  201x-xx-xx-raspbian-jessie.zip  Raspbian  Jessie with PIXEL : Full Image with PIXEL Desktop  Jessi Lite : Minimal Image  Burn Image to SD Card  ETCHER  https://etcher.io/  Windows, MacOSX, Linux  Win32Disk Imager  https://sourceforge.net/projects/win32diskimager/  Windows Only   setup  As a PC  Connect Monitor, Keyboard, Mouse and Internet  Network setup  SSH Connection  As a develop board  Serial Consol TTY  USB-Serial Convertor  USB(PC) to UART(R-Pi)  Network setup  SSH Connection  Direct Ethernet cable(Internet Sharing)  Ethernet(PC) – Ethernet(R-Pi)  Network setup  SSH Connection  As a PC  Easiest way to setup but inconvenient  Connecting  Monitor using HDMI Cable  Mouse/Keyboard using USB  Ethernet Cable  Insert SD Card  Power In  As a PC  open editor as sudo  Run  sudo leafpad  As a PC  static IP setup  File > Open  /etc/dhcpcd.conf  Serial Console TTY Enable  Eject SD card reader and Connect to PC again  Check ‘boot’ drive and 2 files in it  cmdline.txt  config.txt  cmdline.txt (Just checking)  config.txt  add “enable_uart=1” at the end of the file  no spaces in the line  Eject SD card from PC, Insert into R-Pi SD slot  No Powering to Raspberry Pi yet.  Static IP setup  sudo vi /etc/dhcpcd.conf (Must Back-up)  sudo reboot  ifconfig eth0  Check IP address  Network Check  ip  ifconfig  ip address  Router  route  ip route  DNS  cat /etc/resolv.conf  Wifi setup  sudo iwlist wlan0 scan  sudo vi /etc/wpa_supplicant/wpa_supplicant.conf  sudo ifdown wlan0  sudo ifup wlan0  ifconfig wlan0  Check IP address  SSH Login  PuTTy  Connection Type : SSH  Host Name : Raspberry Pi IP Adress  Port : 22  Save RSA Key  Login  ID : pi  Passwrd : raspberry  Software Configuration  sudo raspi-config  4 Internationalisation options  Time Zone > Asia > Seoul  Change Locale  en_US.UTF-8  ko_KR.EUC-KR  ko_KR.UTF-8  Default : en_US.UTF-8  Change Keyboard layout  Generic 105-Key  Korean-104Key Compatible  Module Update  sudo apt-get update  sudo apt-get upgrade  Install Korean Font  sudo apt install fonts-unfonts-core  Install Korean Keyboard Input  sudo apt install ibus  sudo apt install ibus-hangul  LCD Monitor setup  http://elinux.org/index.php?title=RPiconfig  /boot/config.txt  BIOS in PC  max_usb_current  Change Usb output limits  600mA j1200mA  hdmi_group  1 : CEA, 2: DMT  hdmi_mode=87  Custom mode  hdmi_cvt  width, height, framerate, aspect, margins, interlace, rb  Remote Desktop - VNC  Raspberry-Pi Configuration GUI  Interfaces  Enable VNC Service  Raspberry-Pi Configuration CLI  sudo raspi-config  Interfaces  VNC  Remote Desktop - VNC  Raspberry-Pi  Server Installation  sudo apt-get install x11vnc  Execute Server  x11vnc  Adjust Resolution  http://elinux.org/Rpiconfig  /boot/config.txt  Remote Desktop - VNC  PC  http://www.realvnc.com/download/  Install VNC Viewer  Remote Desktop - xrdp  Raspberry-Pi  Server Installation  sudo apt-get remove vnc4server  sudo apt-get remove tightvncserver  sudo apt-get install tightvncserver  sudo apt-get install xrdp  File for server setting  /etc/xrdp/xrdp.ini  PC(Windows Only)  Start > mstsc (Remote Desktop)  sesman-XVnc  pi / raspberry  Python  https://www.python.org/downloads/release/python-2711/  Version 2.7.x, Not 3.5.x  Python  Installation on PC  Default Path  Enable "Add python.exe to path" Option  Python  Hello World  REPL(Read-Eval-Print-Loop)  open Windows command console  execute 'python' command  python shell prompt opened  execute 'print "Hello world"  command 'exit()'  Source Code  make a file named 'hello_world.py'  execute command  python hello_world.py  WinSCP  SFTP : FTP based on SSH  Transfer/ Receive File  https://winscp.net/eng/download.php  WinSCP  Installation  Default Options  WinSCP  Connect to RaspberryPi  WinSCP  Left Pannel : PC Local File System  Right Pannel : Remote, RaspberryPi File System  File upload : File > Upload (F5) to /home/pi  Python on RaspberryPi  Open PuTTY  Check the file "hello_world.py" uploaded  ls hello_world.py  Execute  python hello_world.py  GCC Cross Compiler for RaspberryPi  http://gnutoolchains.com/raspberry/  Appropriate version for Raspbian Image installed  GCC Cross Compiler for RaspberryPi  Install on PC  Default Options  GCC Cross Compiler for RaspberryPi  Check Installation  C:\SysGCC\Raspberry\bin\arm-linux-gnueabihf-gcc --version  Source Code "hello_world.c"  make file named hello_world.c  GCC Cross Compiler for RaspberryPi  Compile  arm-linux-gnueabihf-gcc -o hello_world hello_world.c  Check the output file named "hello_world"  Upload to RaspberryPi using WinSCP  /home/pi/hello_world  Check and change permission the file on RaspberryPi  ~$ file hello_world  ~$ chmod 777 hello_world  execution the file  ~$ ./hello_world  NodeJs  Download for PC(Windows)  https://nodejs.org  LTS Version  NodeJs  Installation on PC  Default Options  NodeJs  Download for RaspberryPi  Too old version(v0.10.x) is installed by default  Determine download version with CPU archtecture  $ uname –m or $ lscpu or $ cat /proc/cpuinfo  RaspberryPi CPU is ARMv8, but Rasbian OS is based on 32bit  NodeJs  Download  wget https://nodejs.org/dist/v6.9.4/node-v6.9.4-linux-armv7l.tar.xz  Extract  tar –xf node-v6.9.4-linux-armv7l.tar.xz  move to /opt  sudo mv node-v6.9.4-linux-armv7l /opt/nodejs  create link  apt-get remove nodejs  sudo ln –s /opt/nodejs/bin/node /usr/bin/node  sudo ln –s /opt/nodejs/bin/npm /usr/bin/npm  NodeJs  check nodejs version  $ node –version  Source Code  make the file named 'hello_world.js' on PC  Run on PC  node hello_world.js  Upload and Run on Raspberry  upload the file using WinSCP  node hello_world.js  JDK(Java Development Kit) Installation  Needed for Eclipse  http://java.sun.com  http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html  Eclipse Installation  http://www.eclipse.org/downloads/  Eclipse IDE for JavaEE Developer  PyDev Installation  Eclipse > Help > Eclipse Marketplace  Search "Python"  PyDev Configuration  Eclipse Preferences  Pydev > Interpreters > Python Interpreter  Quick Auto-Config  Python Project  Create a Python new project  New > Project  Create a Python Source Code File  New > PyDev Module  Python Project  Python Code  Running  R Click > Run As > Python Run  Eclipse CDT(C/C++ Development Tooling) Installation  Eclipse Help > Install New Software  Click Add Button  Name : CDT  Location : http://download.eclipse.org/tools/cdt/releases/9.2  Eclipse CDT(C/C++ Development Tooling) Installation  Eclipse Help > Install New Software  Add Button Click  Name : CDT  Location : http://download.eclipse.org/tools/cdt/releases/9.2  check all items  uncheck Arduino C++ Tools  C Project  R Click > New Project  C Project  Fill in the Project Name  Project Type  Hello World ANSI C Project  Toolchanis  Cross GCC  C Project  Basic Settings  Fill in the blanks appropriately  C Project  Select Configurations  Leave it as defaults  Checked Debug, Release  C Project  fill in the blanks correctely  cross compiler prefix  arm-linux-gnueabihf-  cross compiler path  C:\SysGCC\Raspberry\bin  Path of the Cross Compiler  C Project  C Source code  Build  Menu > Project > Build All  Check the result  Console message  output file under Debug  C Project  Running  Upload using WinSCP  Execute the file on the RaspberryPi using PuTTY  Eclipse NodeJs Configuration  Nodejs Plugin Installed by default on Eclipse Neon  Check the Configuration  You can customize  NodeJs Project  Create a Nodejs Project  R Click > New Project > Javascript Project  NodeJs Project  Fill in the project name  Leave all other items as default  Click Finish  NodeJs Project  Create Source Code File  R Click > New > File  Fill in the File Name with .js extention  Click Finish button  Edit File  Running  R Click > Run As > Node.js Application  Check the result on the Console  RemoteSystem Setup  You can control the Remote RaspberryPi with Eclipse  Open Perspective  Eclipse > Window > Perspective > Open Perspective > Other  Remote System Explorer  RemoteSystem Setup  Register a new Connection  Remote System > R Click  Login  Apply Python Project to Remote  Export project produced in PyDev Perspective  Remote Systems > Remote File System  Apply Python Project to Remote  Select a directory on RaspberryPi  Apply Python Project to Remote  Select Destination  Check "Review/Sysnchronize" Option  Apply Python Project to Remote  Put the file to apply using Synchronize view  Apply Python Project to Remote  Executing remotely using PuTTY.  Apply C Project to Remote  R Click on the Project  Run As > Run Configurations  Select "C/C++ Remote Application"  create new run configuration  new connection  connection type  SSH  Apply C Project to Remote  New Connection  Fill in the blanks  Remote path  Select properly path on the remote Raspberry Pi  Apply C Project to Remote  Commands to execute before application  chmod 744 path/to/output_file_name  Check the result in the Console view  Apply NodeJs Project to Remote  NodeJs Project Export  Remote Systems > Remote File System  Select a directory on RaspberryPi  Check "Review/Synchronize" option  Apply NodeJs Project to Remote  Put the file to apply using Synchronize view  Executing remotely using PuTTY.  Unix  Multics for GE646 by AT&T, GE, MIT in 1964  Multi User, Multi Processing, Multi Process  Pulled down for many problems in 1969  Unix  AT&T Lab  1971' Re-do in Assembly by Ken Thompson(US, 1943 ~ )  1973' Re-written in C language by Dennis Ritchie  US, 1941 ~ 2011  Developed C language to Write Unix  UC Berkley  Buy Source Code from AT&T  Added TCP/IP Stack  BSD version  System V from AT&T  Solaris, HP-UX, AIX  BSD from UC Berkley  SunOS, FreeBSD  Minix  Minimal Unix-like OS, 1987 Andrew Stuart(Nederland, 1944~)  For Education only  Linux  1991' University of Helsinki, Linus Torvalds(Finland, 1969~)  Created Unix like OS on Minix  Free Software, GNU GPL  Distributions  Red Hat  Famous in Enterprise Server  Package Manager : RPM  Fedora, CentOS, 붉은별  Debian  Famous in Desktop  Package Manager : APT  Ubuntu, Rasbian, Mint  Slack ware  OpenSUSE, Slax  Unix like System  Minix  Linux  Mac OSX  POSIX(Portable Operating System Interface)  suggested by Richard Stallman(1953 ~ ) in 1985  Standards for Unix Interface  Certified  AIX  HP-UX  IRIX  macOS, Darwin  Solaris  FreeBSD  NetBSD  Linux  VxWorks  Unix/Linux System Structure  Kernel  File System  Shell  Kernel  Core Component  Device Management  Memory, Process Management  File System Management  CPU Control  File System  Hierarchical Directory and File, /(root)  Managing Files in Disks  Mapping Devices, Processes to Files  Linux FS  Ext3, Ext4  Shell  Interfacing between Human and Kernel  Shells  Bourne Shell  Unix Orinate  C Shell  Similar C language  Korn Shell  Unix Standard  Improved Bourne & C  Bash Shell  Most Linux Shells  Bourne Again  Z Shell  Mordern Style  Command Line Interface  Command  Shell Built-in Command  Execution File in PATH  Options  Optional  dash(-) character  Additional Requirements  Modifiers for Command  Arguments  Optional or Mandatory  Object of Command  Target to Execute  Command Line Interface  Command Only  No options  Default Options  No arguments  Objects or Targets omitted  Examples  uname  date  cal  ls  Command Line Interface  Command + Options  Additional Requirements  Common Options  -a : all  Command Line Interface  Command + Arguments  Target Specific  No omitted  Command Line Interface  Command + Options + Arguments  Command chaining  Executing Multi Commands Simultaneously  ; - Semi Colon(;)  command-1; command 2; command-n  sequential Separated N command  No effect error  && - Ampersand X 2  No Single & (Background)  Depends on Error  Stop If Error Occurs  Control Characters  Process  Ctrl + c : Interrupt(terminate) current process, SIGINT  Ctrl + d : EOF(End of File) or EOT(End of Transmission) Character  Ctrl + z : Suspend current foreground process, SIGSTP  Cursor  Ctrl + a : move cursor to start of line  Ctrl + e : move cursor to end of line  Screen  Ctrl + u : Clear current line  Ctrl + w : Clear current word  Ctrl + l : Clear screen  Ctrl + s : Stop output to the screen  Ctrl + q : Resume output to the screen stopping with Ctrl + s  Types of Command  Shell Built-in  Internal Command  Shell Command  Executable Program File  External Command  All Files has X mode in disk  Specified the location in $PATH env  /bin : basic command for normal users  /sbin : basic command for administrators  /usr/bin, /usr/sbin : command for specific class user  ex : office user, developer, gamer  /usr/local/bin, /usr/local/sbin : user compiled, installed program  Types of Command  Shell Built-in  List up  help  Detail Information  help  Distinguish  type  Executable Program File  List up  echo $PATH  Detail Information  --help  man help  Location  which  Manual page  From Unix Manual Paper Book  online : http://man7.org/linux/man-pages/index.html  Manual page  man  Navigate key  enter : next line  space : next page  b : prev page  /pattern : search pattern  n : next pattern  q : exit  SEE ALSO  Relative Command  Section Number  Command(n)  Manual page  Inquiring in section  man –s  man  Keyword  man –k  pwd  present working directory  ls  list up files and directories  ls options pathname  -l : long, detail  -a : all, no hidden file  -d : directory  -R : recursive  -F : file type  / : directory  * : executable  (none) : text  @ : link  ls file  ls /dir  ls -l  Tree  list directory like tree-format  -d : directory only  -L : depth level  -P : pattern only  -I : ignore patten  File  determine file type  -i : MIME type  -L : symlink  Stat  display file or file system status  Directory Command  mkdir  make directory  -p : make parent  cd  change directory  Path  Absolute vs Relative  . : current dir  .. : parent dir  ~ : home dir  / : root dir  - : previous  Making a File  touch  no content in the file  zero size  echo 'content' >  echo 'hello world' > hello.txt  echo & redirection  Editor  nano  vi  Nano Editor  Linux Basic Test Editor  nano [FILENAME]  Ctrl + X : eXit  Ctrl + O : Save  Ctrl + K : Cut, Copy  Ctrl + U : Paste  Ctrl + ^ : Block  Ctrl + W : Search  Ctrl + G : Help  cp (Copy)  Copy File or directory  cp option source target  File Copy  new file name  cp fileA fileAA  new file name to other dir  cp fileA dirA/fileAA  no file name to other dir  cp fileA dirB  -i : Interactive  prevent overwriting  cp (Copy)  Directory Copy  -r : recursive  To new directory  cp –r dirA dirZ  create new directory  To existing directory  cp –r dirA dirB  copy to child directory  mv (Move)  Move File or Directory  To Move File  File name only  mv fileA fileX  The same with rename  New path  mv fileB dirB/fileX  mv (Move)  To Directory  To new directory  mv dirA dirX  create new directory  To existing directory  mv dirB dirC  move to child directory  rmdir (Remove Empty Directory)  rmdir [option] DIRECTORY...  -p : parent  Remove ancestors  only empty directory  if not empty  fail  use rm  rm (Remove File or Directory)  rm [options] file_path  -r : recursive  Not Empty  -f : force  ignore nonexistent  -d : empty directory  Display File content  cat [OPTION] [FILE]  concatenate file to output  If no file, standard input  more FILE  paging one screen  scroll  enter : next line  space : next page  b : prev page  / : search  n : next pattern  q : quit  head [OPTION] [FILE]  output the first part  -n : first NUM lines  tail [OPTION] [FILE]  output the last part  -n : last NUM lines  -f : following  wc (Word Count)  wc [OPTION] FILE  no option : lines, words, bytes  -l : line counts  -w : word counts  -c : byte counts  -m : character counts  useful with pipe(|)  grep  grep [OPTION] PATTERN [FILE..]  print lines matching a pattern  OPTION  -i : Ignore case  -l : print file name  -n : line number  -v : invert match  -c : count  -w : word searching  -E : extended regexp  -F : fixed string  -r : recursive  egrep  grep -E  fgrep  grep –F  rgrep  grep -r  find  search files  find path expression action  expression  -name filename  'filename*' : * with quotation mark  -type filetype : f, d, c, b ...  -size [+|-]n[c,k,M,G]  -atime, -amin, -mtime, -mmin, -ctime, -cmin [+|-]n  -user owner_id  -perm [-|/] mode  - : match all bit  / : match any bit  -maxpeth n  find expression  find expression  find –perm  find  search files  find path expression action  action  -print(default) : path and name  -ls : print detail  -delete : delete files  -exec command [{}] \;  -exec command {} +  execute command  {} : Result of find  \; : execute separately  + : execute at once  -ok command [{}] \; : execute command interactively  find action  find –exec  Standard I/O  Redirection  Input from file instead of stdin  file_name : overwrite  >> file_name : append  output to file instead of stderr  2> file_name : overwrite  2>> file_name : append  Redirection  /dev/null  Null Device  Special File to discard useless data  command 2> /dev/null  discarding useless error messages  > file_name 2>&1  Redirecting stdout, stderr to same file  Pipe ( | )  Connect stdout of process(A) to stdin of another process(B)  A | B  tee  Read from stdin, write to stdout and file  Good for output both stdout(terminal) and file  Using Redirection and Pipe Together  -a : append  Linux File Mode  Determine can read, write, execute  File type  - : Normal file  d : Directory  l : Symbolic link  s : socket  p : Named Pipe  c : Character device  b : Block device  User  Owner  Owner ID  Group  Member of the group  Other  Not a owner, Not a member  File Permission  Determine Permission  id [USER]  print user and group  Change Permission  chmod mode filename  symbolic mode  Target  u : owner  g : group  o : other  a : all (default, except umask bit)  Operator  + : add  - : remove  = : assign  Permission  r : read  w : write  x : execute  Change Permission  Symbolic mode  Change Permission  chmod mode filename  Octal mode  3 digit in octal  Change Permission  Octal Mode  Change Owner  chown id FILENAME  chown id : group FILENAME  chown :group FILENAME  Change Group  chgrp gid FILENAME  Umask  newly created file's permission  umask : print umask  umask value : set umask  Umask Calculation  Default – Umask_value  2's Complement of umask  AND operation  Default Permission  Directory : 777  File : 666  Example, umask=0022  Umask  File System  Control how data(File) is stored and retrieved  Windows : FAT, NTFS, exFAT  Unix : UFS  Linux : Ext2/3/4, XFS,JFS  MacOS : HFS  Flash : UBIFS, JFFS2, YAFFS  Linux File System  Boot Block (Boot Sector)  At the beginning of Storage  Special data to start a system  Super Block  File system metadata (Type, Size, Status)  Information of I-Node, Data block  I-Node Block  Represents a File  Stores data of permission, owner, size, pointer of Data Block  Data Block  Contain file data and directory  can be multiple per file  I-Node & Data Block  ls –il  -i : inode  Directory  Directory is a file  Stores file list  Pair of I-Node number and file name  Link Count  Every Directory has 2 items  . (Current)  .. (Parent)  Sub Directory Count  Link  Connection between a file and data  Hard Link  Low-level link  Make another File Name  But not make I-Node, has the same I-Node number  No difference between the original and the link  Increment Link Count  Cannot make a hard-link to directory  Soft(Symbolic) Link  Similar to Windows shortcut icon  Make a new file pointing to the original file  File Type : l, @  Permission : 777  Link  Update and Read  Always the same effect  Original, Hard-link, Soft-link  Remove Link  Remove origin  No effect on hard-link  Make Dangling soft-link  Restorable, Creating a file with the same name as origin  Remove hard-link  No effect on origin, soft-link  Remove soft-link  No effect on origin, hard-link  Finding Link  Hard link  find . -samefile  find . -inum  Symbolic link  find . -lname  vi [File Name ]  Mode  command mode  edit mode  last line mode: Input command at the last line  Vi Edit Mode  i : Input in front of curser  a : Input after the curser  o : Input after adding a line at the end of curser  O : Input after adding a line before curser  A : Input at the end of curser line  I : Input in front of curser line  r : Overwrite one unit at the curser position  R : Overwrite exiting character from curser position  x : Delete a unit  dd : Delete a line  u : Redo  Vi Moving Curser  h : Move left  j : Move down  k : Move up  l : Move right  ^ , 0: To the beginning of the line  $ : To the end of the line  G : To the end of the document  1G : To the beginning of the document  Number G : Move to number line  Ctrl + D : A half page down  Ctrl + F : A half page up  Ctrl + B : One page up  Ctrl + U : One page down  Vi Copy/ Paste  yy : Copy the line with curser  Number yy : Copy lines as numbered  x : Cut one unit where the curser is located  p : Paste  Number p : Paste lines as numbered  Block Mode  v : Blurred Mode  y : Block Copy  p : Block Paste  d : Block Delete  > : Block Tap   A –lt B : check if A is less than B, =  A –le B: check if A is less than or equals to B, dash , minimal shell of bash for executing shell  execute command in the new shell process  my.sh  chmod +x  she bang  #! /bin/sh  #! /bin/env sh  execute command in the current shell process  source my.sh  source : execute command in the current shell process  . my.sh  . is alias for source  Shell Initialization  When the shell is invoked, startup files  system wide startup  /etc/profiles  set PATH, PS2  invoke /etc/profile.d/*.sh  /etc/profile.d/*.sh  custom changes  user-specific startup  ~/.bashrc  ~/.bash_aliases  invoked from ~/.bashrc  Shell Initialization  alias [-p]  list up defined alias  alias NAME=VALUE  define alias NAME for VALUE  ~/.bash_aliases  invoked from ~/.bashrc  23 Handy bash shell aliases  https://www.linuxtrainingacademy.com/23-handy-bash-shell-aliases-for-unix-linux-and-mac-os-x/  Process  An Instance of Program running  init (systemd) process  /sbin/init j /lib/systemd/systemd  First process after booting  Ancestor of all process  PID(Process Identifier) is1  ps –p 1  Parent Process  process that created child  Child Process  process that is created by parent  Deamon Process  not require controlling terminal  Orhpan Process  parent dies or get killed before the child  init process adopts  Zombie Process  child dies but parent does not fetch termination status  Searching Process  ps –ef | grep command  pgrep –l command  SIGNAL  Limited form of Inter Process Communication  Signals  kill -l  SIGNAL  Major Signals  sending signal  kill –signal target  Background Process  command &  run in background  ctrl + z  go stopped in background  jobs  list up background  run in background  fg [job_id]  run in foreground  nohup  run command ignoring hangup signals  nohup COMMAND &  Init and Systemd  First Process started during booting  continues running until the system is shut down  SysV style  Traditional init system from Unix  7 Run-levels  /etc/inittab  /etc/init.d/*  /etc/rc[0-6, S].d/*  systemd  Replacements for init  Since  Debian Jessie v8, 2015  RedHat v7.0, 2014  /lib/systemd/systemd  /lib/systemd/system/*.service  Run Level  mode of operation  7 run-levels in Linux SystemV init  Run Level  Systemd target  Mapping runlevels and systemd target  Determine current run level  runlevel  who –r  Change run level  sudo init [0-6]  shutdown  -P : power off  -h : power off  -H : halt, lowest state leaves it power on  -r : reboot  -c : cancel shutdown  -k : shudown warning to users  halt  -p : poweroff  poweroff : power off the machine  reboot : reboot the machine  wall : write a message to all user  Run Level  Setting Run Level  /lib/systemd/system/default.target  change symbolic link to  /lib/systemd/system/poweroff.target ( runlevel0 )  /lib/systemd/system/rescue.target ( runlevel1 )  /lib/systemd/system/multi-user.target (runlevel2, 3, 4)  /lib/systemd/system/graphical.target (runlevel5)  /lib/systemd/system/reboot.target (runlevel6)  Startup Service  Process that require autorun after booting  /etc/rc.local  System V Init Style Compatable  Invoked by /lib/system/system/rc-local.service  add command in the file  /lib/system/system/myd.service  Systemd Init Style  Create .service file  systemctl enable  systemctl start  systemctl stop  systemctl disable  Example shell, myd.sh  write time to ~/date.log every seconds  save as /home/pi/myd.sh  chmod +x myd.sh  Startup Service  Easy way : rc.local  open /etc/rc.local  add the command that invokes myd.sh before "exit 0"  su – pi –c '~/myd.sh' &  Reboot and Check the process  Startup Service  Add Service : myd.service  Create file /lib/systemd/system/myd.service  Startup Service  Add Service : myd.service  Enable and Start  Reboot and Check the Process  Stop and Disable  Getting User Information  Determine Current or User  id [ID]  who am i  Get all users logined  who  users  /etc/passwd  stores all user accounts information  Getting User Information  sudo passwd -aS  display all user accounts information  Getting User Information  sudo chage -l  display user accounts expiry information  Adding User Account  sudo adduser  add a user or group to the system  Changing Password  passwd  own password  passwd must not be short  sudo passwd  someone else's password  passwd can be short  Creating Group  sudo groupadd  add a group to the system  List up all Groups  cat /etc/group  Adding a user to an Group  sudo adduser  Remove a user from group  sudo deluser  Getting Super User authority  add user to sudo group  /etc/sudoers  sudo adduser sudo  Sudo with No Password  make a file in /etc/sudoers.d  no contain '~' or '.'  Substitute User  su [-]  - , -l, --login : login shell  Unset all variable and set again  Change Home directory  Become a Root  su – root  su -  Remove a existing group from system  sudo delgroup  Remove a User from system  sudo deluser  Enabling Root Account  NOTE : Not Recommended  Root Account is locked and not set password  Unlock  Set New Password  Enabling Root Account  NOTE : Not Recommended  Allow login through ssh  /etc/ssh/sshd_config  #PermitRootLogin prohibit-password j PermitRootLogin yes  Disabling Root Account  Lock Account  Delete Password  sudo passwd –dl root  top, htop  Display Processes, cpu info, memory info  df  Show disk space usage  -k : kilo  -h : human readable  tar (tarballs)  make archive file  tar -cvf a.tar /abc /def aaa bbb  make archive with zip compression  tar -cvzf a.tar.gz /abc /def aaa bbb  extact archive file  tar –xvf a.tar  extract archive with zip compression  tar –xvzf a.tar.gz  Disk Utilities  lsblk  list block devices  fdisk  manipulate disk partition table  -l : list up  dd  data duplicate, convert and copy a file  dd bs=n if=input_file of=output_file  mount  -l : list up  mount [Device] [Mount_point]  umount  unmout file system  umoun