Handout # 2

1. Handout # 2

2. Linux • LINUX was created by Linus Torvalds in 1991 • 48% of US smartphone users use Android • Used by a majority of webservers (65% use Apache, according to Netcraft, Apr 2012) • 91% of the fastest 500 supercomputers run • LINUX/UNIX has three most important parts. • They are Kernel, Shell and File System • Shell Types • Bourne Shell (sh) (First shell by Stephen Bourne) • C Shell(sh) • Korn Shell (ksh) • Bourne Again Shell(bash)

3. File System • Linux files are organized by a hierarchy of labels, commonly known as hierarchy structure. • There are three types of files. • Regular Files: • This contains a sequence of bytes that generally corresponds to code or data. • Directory Files: • Directory file contains an entry for every file and subdirectory that it is placed. • Device Files: • These files correspond to the printers or other devices connected to the system.

4. Standard directory structure • ◮ / - the topmost • ◮ /dev - all the devices are accessible as files • ◮ /var - “variable” data such as mails, log files, databases • ◮ /usr - almost all the packages installed • ◮ /etc - configuration files • ◮ /home - home directories for all the users • ◮ /root - home directory of the privileged user root • ◮ /mnt - used to mount other directories/partitions.

5. Standard Directories in LINUX • Directory: /bin • /bin contains the binaries which are needed to run LINUX. • Directory: /boot • /boot has all the files required for booting LINUX on system. • Directory: /dev - /dev has the devices for all the files. • Directory: /etc • /etc contains the configuration files of the various software. • v Directory: /opt Here optional softwares are installed. • v Directory: /root The directory for the user root

6. Standard Directories in LINUX • Directory: /home • /home is like My Documents in Windows. • Directory: /lib • /lib contains the libraries required fo r the system files. • Directory: /lost+found • /lost+found contains the files which are damaged or which are not linked to any directory • Directory: /mnt • This is the directory in which we mount the devices and other file systems.

7. Linux GUI • Intro to Unity • ● Launcher (At the Left) • ● Menu Bar (At the Top) • ● Dash

8. Application Software • OpenOffice • oowriter is a viewer and editor for MS Office like document files • ooimpress is used for preparing Power point like Presentations • oodraw is used for preparing drawings. • oocalc is used to open and edit Spreadsheet like xls or sxc files • firefox is used to open Mozilla web browser. • Editors • Editors are the one by which we can edit the files. • There are two types of editors and they are • Textual editor. • Graphical editor.

9. Editors • The textual editors are • vi/vim • emacs • pico • The graphical editors are • gvim • emacs/xemacs • dtpad (CDE) • jot (SGI)

10. Basic Commands • File and Directory Commands • Process Management • Archival • Advanced Commands • Keyboard Shortcuts

11. File and Directory Commands • du – estimate file space usage • df – report filesystem disk space usage • quota – display disk usage and limits • fdisk – partition manipulator • mount – mount a file system

12. File and Directory Commands • cd – changes directories • pwd print name of current working directory • ls - list directory contents • ls has many options: • -l à long list (Displays lots of info) • -t à lists by modification date • -S à lists by size • -h à lists file sizes in human readable format • -r à Reverse the order • -a à Lists all hidden files • -F à Lists files of Directory

13. File and Directory Commands • Deleting Files - rm • Copying and moving files - cp, mv • Creating directories - mkdir • Deleting Empty Directory - rmdir • $ rm Testing.java • //deletes the file Testing.java • $ cp Testing.java Copy.java • //creates the copy of Testing.java • $ mv Testing.java Test.java • //renames the file Testing.java to Test.java • $ mkdir newDir • //Creates directory newDir • $ rmdir newDir • //deletes directory newDir newDir should be empty

14. Process Management • ps – report a snapshot of the current processes • Usage: ps [OPTION] • eg. ps, • • kill – to kill a process(using signal mechanism) • Usage: kill [OPTION] pid • eg. kill 9

15. Archival • tar – to archive a file • Usage: tar [OPTION] DEST SOURCE • • zip – package and compress (archive) files • Usage: zip [OPTION] DEST SOURSE • eg. zip original.zip original • • unzip – list, test and extract compressed files in a ZIP archive • Usage: unzip filename

16. Advanced Commands • reboot – reboot the system • Usage: reboot [OPTION] • eg. reboot • • poweroff – power off the system • Usage: poweroff [OPTION] • eg. Poweroff • who command tells you the users currently logged on to the system • kuteer:˜$ who

17. Keyboard Shortcuts • [Ctrl] e : moves cursor to the ending of the command • [Ctrl] a : moves the cursor to the starting of the command • [Ctrl] l : clears the command window. Functions like clear command. • [Ctrl] z :to suspend the process (moves the process into background ). bg can be used to find the background jobs. fg can be used to bring the background job into foreground. • [Ctrl] c or [ctrl] |: kill the process. • [Ctrl] u : erase the current line. • [Ctrl] k : erase the line from the position of cursor • [Ctrl] w : delete the word before the cursor

18. Starting a Terminal • To open a Terminal do as follow: • Choose Applications → Accessories → Terminal; • Or press Alt+F2 and type gnome-terminal.

19. Writing First Program in C/C++ in Ubuntu • Steps should apply to any Linux distribution • Install the build-essential package by typing the following command in the terminal: • sudo apt-get install build-essential

20. Step 2 • Now create a file that has the extension .c • (if you plan to write a C program) or .cpp (for a C++ program). • for example /usr/src/first.c • sudo gedit first.c

21. Step 3 • Write the code in that file • Example #include <stdio.h> int main () { printf("Hello, This is my First Program in Ubuntu !!!!"); return 0; }

22. Step 4 • Now open a terminal and go to the place where you saved that file using the cd command (e.g. cd /usr/src/)

23. Step 5 • If you have a C program type in the terminal • gcc -Wall -W -Werror first.c -o first • The first line will invoke the GNU C compiler to compile the file first.c and output (-o) it to an executable called first. • The options -Wall -W and -Werror instruct the compiler to check for warnings.

24. Step 6 • If you have a C++ program simply replace gcc with g++ and first.c with first.cpp. The options do the same things • If you get a permissions error, you need to make the file executable. You can do this with chmod +x first.c or first.cpp

25. Step 7 • Now type in the terminal ./first and the program will run • Repeat these steps for a C++ program