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Introduction to Linux

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Introduction to Linux

  1. 1. © 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Introduction to Linux
  2. 2. 2© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. What to Expect? Introduction to OS & OSS Linux System Overview Linux Usage Basics
  3. 3. 3© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. OS Fundamentals What is an OS? Infinitely Running Program Why do we need an OS? Processor/Time Management Memory Management Storage Management Network Management I/O management
  4. 4. 4© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Open Source Software Fundamentals Originally Free Software Freedom to Run, Change and Redistribute Licenses – GNU GPL (Code) and GNU FDL (Doc) The Freedom provides openness Hence, also referred as Open Source Software Over time FS & OSS have differed But still largely same Latest Complete Definitions FS: http://www.gnu.org/philosophy/free-sw.html OSS: http://www.opensource.org/osd.html
  5. 5. 5© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. OSS: Industry Advantage Stable Software – Less Development Cycle Whole Community Support Time to Market And most of all, today OSS provides almost a complete set of software required for any kind of software development Applications, GUIs, Utilities, … - All GPL or LGPL stuff Languages – Whole set from the world :) C Compiler – gcc & friends Debuggers – gdb & friends Profilers, Tracers, ... and the list goes on
  6. 6. 6© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. And finally the most important one OS + OSS = Linux
  7. 7. 7© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Why to choose OSS & Linux? Quality and Reliability of Code Availability of Code Extensive Hardware Support Communication Protocols and Software Standards Available Tools Community Support Licensing Vendor Independence Cost And, a wide range of Architecture Support
  8. 8. 8© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Linux on Architectures x86 Started with this Mainly intended for PCs Power PC Intended for PC Have become popular in embedded Strong ARM Faster CPU – Higher Performance PDAs, Setup box etc. ARM Suits well for Embedded Include THUMB – reduce code bandwidth High density code than PPC, x86 Many More Alpha, H8, MIPS, Sparc, SuperH, ...
  9. 9. 9© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Linux System Overview
  10. 10. 10© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. The Complete Software System Operating System “Kernel Space” OS Services Applications “User Space” Hardw are
  11. 11. 11© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Linux Kernel Subsystem The Process Scheduler (SCHED) The Memory Manager (MM) The Virtual File System (VFS) The Network Interface (NET) The Input/Output System (IO) Additionally, the Inter-Process Communication (IPC)
  12. 12. 12© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Linux Kernel Subsystem ... Process Scheduler Memory Manager IPC Network VFS
  13. 13. 13© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Linux OS Services System Call Interface X Window System
  14. 14. 14© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Linux Applications Shell Terminal / Console Window Manager Editor Compiler ...
  15. 15. 15© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Linux Usage Basics
  16. 16. 16© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Topics Root & System Directories Shell Basics & the 'bash' Shell File Basics & related Commands User Basics & related Commands File Access Permissions System & Help Information Standard I/O, Redirection and Pipes
  17. 17. 17© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. / the Root of an inverted tree The top-most or super-parent directory The container of your computer Type: ls /
  18. 18. 18© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. System Directories /bin, /sbin - system binaries/applications /var - logs, mails /proc, /sys - “virtual” windows into the kernel /etc - configuration files /lib - shared system libraries /dev - device files /boot - Linux kernel and boot related binary files /opt - for third-party packages /root, /home - home directory for super user & other users /usr - user space related files and dirs (binaries, libraries, ...) /tmp - scratch pad /mnt - mount points
  19. 19. 19© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Shell Basics What is a Shell? Various types of Shells Bourne Shell (sh) C Shell (csh) Korn Shell (ksh) Bourne Again Shell (bash) TENEX csh (tcsh) Z Shell (zsh) Busybox (busybox) – Embedded Systems
  20. 20. 20© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Bourne Again SHell env - shell environment variables export [var_name] - export a shell variable HOME - path to user’s home directory PATH - executable search path PWD - present user directory PS1 - command prompt which - shows executable path history - command recall
  21. 21. 21© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Bourne Again SHell ... alias - create shortcuts to commands file - shows the information about a file type - shows information about a command Scripts /etc/profile - System wide startup script ~/.bash_profile – User specific startup script ~/.bashrc – Shell specific startup script ~/.bash_logout – User specific shutdown script
  22. 22. 22© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. File Basics Every thing is viewed as a file in Linux A file under the / Seven Types Regular (-) Directory (d) Character Device (c) Block Device (b) Named Pipe (p) Socket (s) Symbolic Link (l)
  23. 23. 23© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. File related Shell Commands ls - list directory/file contents cd - change directory pwd - print working directory df - disk free du - disk usage cp - copy mv - move, rename rm – remove mkdir - make directory rmdir - remove directory cat, less, head, tail - used to view text files vi, vim - editors touch - create and update files grep - search in files find, locate - search for files gzip, gunzip, bzip2, bunzip2, xz, unxz - compression tar - archive sed, awk - file manipulation
  24. 24. 24© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. User Basics All Accesses into a Linux System are through a User with a Password Super User – root Normal Users - <user_name> Files: /etc/passwd, /etc/shadow Users can be categorized into groups root, bin, sys, adm, … File: /etc/group
  25. 25. 25© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. User related Shell Commands useradd - create user userdel - delete user usermod - modify user su - <username> - start new shell as different user finger - user information lookup passwd - change or create user password who, w, user - to find out who is logged in
  26. 26. 26© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. User & File Access All Files have User specific ownerships & access permissions Type: ls -l –rw–r––r–– Symbol Name Number Position r read 4 r-- w write 2 -w- x execute 1 --x type user group other user (anil) group (anil)
  27. 27. 27© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Related Shell Commands chmod – Change file permissions chown – Change file owner chgrp – Change file group
  28. 28. 28© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Few “Help”ful Shell Commands uname - print system information man <topic> - manual pages info <topic> - information pages
  29. 29. 29© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Linux Manuals Divided into sections 1 Shell commands e.g. mv, ls, cat 2 System calls e.g. _exit, read, write 3 Library calls e.g. exit, printf 4 Device and network specific info e.g. mouse, ttyS, null 5 File formats e.g. passwd, termcap 6 Games and demos e.g. fortune, worms 7 Miscellaneous e.g. ascii, fifo, pthreads 8 Administrative commands e.g. fsck, network daemons 9 POSIX Programmer Manual Info pages are also available
  30. 30. 30© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Standard Input & Outputs Standard Input – 0 (default: keyboard) Standard Output – 1 (default: monitor) Standard Error – 2 (default: monitor) Examples read echo q
  31. 31. 31© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Redirections & Pipes command < file - reads standard input from file command > file - directs standard output to file command >> file - appends standard output to file command 2> file - directs standard error to file command 2>> file - appends standard error to file command > file 2>&1 - both standard output & error to file cmd1 | cmd2 - transfer o/p of cmd1 as i/p to cmd2
  32. 32. 32© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. What all have we learnt? Introduction to OS & OSS Linux System Overview The 3 software layers The hardware core Linux Usage Basics Root & System Directories Shell, File, User Basics System & Help Information Standard I/O, Redirection and Pipes
  33. 33. 33© 2010-19 SysPlay Workshops <workshop@sysplay.in All Rights Reserved. Any Queries?

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