1. Introduction to UNIX Road Map: 1. UNIX Structure 2. Components of UNIX 3. Process Structure 4. Shell & Utility Programs 5. Using Files & Directories 6. Compiling and Running C Programs in UNIX

2. UNIX Structure  Multiuser : Several users can use a UNIX system at the same time.  Multitasking : Can run multiple processes at the same time. Hardware UNIX Kernel POSIX system call API P1P1 P2P2 PNPN …

3. Components of UNIX 1. Kernel + POSIX system call API ◦ Covered in OS 2. Shell (program to launch other programs) 3. Standard utility programs ◦ ( cp, mv, ls, cat, … ) 4. System configuration files ◦ ( /etc/vfstab,… )

4. Process Structure init login login (/bin/login)login shell (/bin/sh) lswccat Other user programs

5. Logging In/Out Login : user1 Password: 123 % command  get a shell prompt % command  get another shell prompt % exit  logout & terminate shell

6. Shell a.k.a command line interpreter  Getting help on UNIX % man ls % man man while(1) 1.prompt the user for the next command 2.Read the next command 3.Parse the command line 4.Launch the programs (fork, exec) 5.Wait until the programs terminate (waitpid) end

7. Running utility programs Most utility programs are located in /usr/bin Basic form of a UNIX command is % command [-options] [arguments] Ex: % ls % ls –a % ls –al % ls BIM322 % ls –al BIM322 % clear  cleans the screen Aborting a shell command: press ^C

8. UNIX has a tree-like hierarchical directory structure. When you login, login utility reads your home directory from /etc/passwd and changes your current directory to be your home directory. Using Files & Directories tmp bin lib usr etc home export dev include bin local bin

9. Directories 1. % pwd print working directory 2. % cd BIM322 change current directory % cd.. change to parent % cd / change to root % cd /usr/local absolute path specification % cd % cd ~ takes you to your home % cd ~cakinlar directory 3. % ls –al list directory content 4. % mkdir AA create a new directory 5. % rmdir AA remove a directory

10. Files 1. % touch file1 create an empty file 2. % cp file1 file2 copy files 3. % mv file1 /tmp move file to directory % mv file1 file3 move file to a new file % mv AA /tmp can also move directories 4. % rm file1 remove a file 3. % find. –name file1 find a file 4. % cat file1 view all at once 5. % more file1 page by page 6. % head file1 first … lines 7. % tail file1 last … lines

11. Compiling and Running C Programs in UNIX 1. Open an editor, type your ‘Hello world’ program. 2. % gcc first.c  outputs a.out 3. %./a.out or %./a 4. % gcc –o first first.c 5. %./first // first.c include int main(int argc, char *argv[]){ int i; for(i=0; i<argc; i++) printf("arg[%d]: %s\n", i, argv[i]); } //end-main // first.c include int main(int argc, char *argv[]){ int i; for(i=0; i<argc; i++) printf("arg[%d]: %s\n", i, argv[i]); } //end-main