Brief Intro to Linux/Unix Brief Intro to Unix (contd) A Brief Introduction to o Brief History of Unix o Compilers, Email, Text processing o Basics of a Unix session o Image Processing Linux/Unix – AMS 2019 o The Unix File System Pete Pokrandt o Working with Files and Directories o The vi editor UW-Madison AOS Systems Administrator o Your Environment [email protected] o Common Commands Twitter @PTH1 History of Unix History of Unix History of Unix o Created in 1969 by Kenneth Thompson and Dennis o Today – two main variants, but blended o It’s been around for a long time Ritchie at AT&T o Revised in-house until first public release 1977 o System V (Sun Solaris, SGI, Dec OSF1, AIX, o It was written by computer programmers for o 1977 – UC-Berkeley – Berkeley Software Distribution (BSD) linux) computer programmers o 1983 – Sun Workstations produced a Unix Workstation o BSD (Old SunOS, linux, Mac OSX/MacOS) o Case sensitive, mostly lowercase o AT&T unix -> System V abbreviations 1 Basics of a Unix Login Session Basics of a Unix Login Session Basics of a Unix Login Session o The Shell – the command line interface, o Features provided by the shell o Logging in to a unix session where you enter commands, etc n Create an environment that meets your needs n login: username n Some common shells n Write shell scripts (batch files) n password: tImpAw$ n Define command aliases (this Is my password At work $) Bourne Shell (sh) OR n Manipulate command history IHateHaving2changeMypasswordevery3weeks!!! C Shell (csh) n Automatically complete the command line (tab) The password speech… [use good passwords] DoIT Password guidelines: TC Shell (tcsh) n Edit the command line (arrow keys in tcsh) https://it.wisc.edu/guides/select-manage-protect-passwords Korn Shell (ksh) n Can log in more than once, in several windows Bourne Again Shell (bash) [OSX terminal] Basics of a Unix Login Session Basics of a Unix Login Session Basics of a Unix Login Session o Logging in to a unix session o Logging off from a Unix session o Changing your password n logout, exit, ^d n passwd (will ask for your old password, then your n Many people can be logged in at the same time via the network n For CentOS Linux, choose System/Log out new one, then new one again to confirm) n Remote login – secure shell [cat3/cat4/cat5.aos.wisc.edu] n In x-windows, click EXIT, right-click in n Windows – SecureCRT or putty (Xming for graphics) background, select logout/exit, try various n If you forget your password – see the systems buttons in the background. n OSX/Linux – from Terminal window administrator, they can change it for you. ssh [email protected] –Y (or –X) n MAKE SURE you are logged out, or others can n Starts in your home directory access your files, do things as you. Also, if the screen locks, others can’t user the machine 2 Basics of a Unix Login Session The Unix File System The Unix File System o Who are you? o What is a file? o Types of files (contd) n id o Types of files .. – A special directory that refers to the n groups – what groups you belong to - Ordinary Files (text, programs, images, etc) parent directory (the one above where you are - Directories (file that holds other files, dirs) n root – the Superuser - administrator now) - Special files (used to represent physical . – A special directory that refers to the devices (printers, disks, etc) - Pipes (temporary file used to hold output from directory that you are in now one command until it is ready to be read by another All directories contain . and .. The Unix File System The Unix File System The Unix File System / o Organized as a heirarchy of directories /bin o Home Directory – where you are when you starting with / (the root directory) /home1 first log in (usually under /home - here, /home1/class/fall06 under /home1/class/fall18) /home1/class/fall06/poker /dev o / is similar to the Windows My o Open Terminal starts in home or /etc Desktop directory Computer, or the Mac Desktop/Finder. /home /home/aos o Current Working Directory (pwd) /home/user1 /lib o Absolute vs Relative Path Names /tmp /home1/class/fall18/poker/dir1/file1 /sbin dir1/file1 3 The Unix File System The Unix File System The Unix File System o Change directory (cd) to dir1 o Common System Directories o Common System Directories (contd) cd dir1 o / - root directory o /usr/include – C include files o /bin – binary executable files o /home/aos– home directory for user aos Now, ways to refer to that same file o /dev – special device files o /tornado/home1/class/fall06/poker – home directory for user poker o /etc – administrative/configuration files/programs o /usr/local – locally added programs, libraries, etc /home1/class/fall18/poker/dir1/file1 o /home – user directories o /usr/local/bin o /lib – libraries used by programs and languages file1 o /tmp – scratch area for temporary files o /usr/local/lib ../dir1/file1 o /usr – system files/directories shared by users ./file1 Using Unix Commands Using Unix Commands Using Unix Commands o Case Sensitive! (ls not the same as Ls or LS) o Use backspace or delete to correct errors o Processes – unique process ID number for stty erase [hit the key you want to every process that is running o The Prompt: where you enter your commands use] o Commands to identify processes agnes[poker] %1 (csh, tcsh) n ps (sh, ksh, bash) agnes$ o Online manual pages for almost all commands n ps –flu poker man man n ps –efl o General command syntax man passwd n ps –aux (bsd type systems) command [-flags] arg1 arg2… man –k compiler 4 Using Unix Commands Using Unix Commands Using Unix Commands o ps –flu poker o Jobs – per shell shortcut of programs running o Killing processes kill pid # ps -flu poker agnes 27% jobs kill –STOP pid F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD [1] + Running firefox kill -9 pid 8 S poker 1047 1 0 99 20 70cb0ec0 155 70cb0f2c o Job Control Jan 16 ? 0:00 /bin/sh ^Z – stop a running job 8 S poker 1049 1048 0 40 20 70ccd5f0 269 7015587a jobs Jan 16 ? 0:00 /var/tmp/lm_TMW12.ld fg %1 8 S poker 1048 1047 0 41 20 70ccceb8 133 70641c1c Jan 16 ? 0:00 sh -c while read line; bg %1 Using Unix Commands Using Unix Commands Using Unix Commands o Typical command locations o PATH environment variable – where linux looks for progs o Locating Programs – whereis, which n /bin agnes 1% echo $PATH n agnes 2% whereis pwd /research/linux_grads/grads-1.9b4/bin: n /usr/bin /research/linux_bin:/research/linux_idv: pwd: /bin/pwd /usr/bin/pwd n /usr/local/bin /research/linux_mcidas/bin: /research/ncl/bin: n agnes 3% which pwd n /home1/class/fall06/poker/bin /usr/local/weather/bin:/usr/local/bin: n /research/linux_bin /bin:/usr/bin:/usr/bin/X11:.: /usr/pwd /research/linux_gempak/GEMPAK7/os/linux/bin agnes 2% rehash agnes 3% ./prog 5 Using Unix Commands Using Unix Commands Using Unix Commands o Several commands can be entered on one o Command History (in C or TC shell) o Command History (in C or TC shell) command line, separated by a ; n history – list previous commands (numbered) n tcsh/bash – arrow keys ls ; date n !! – repeat previous command n up/down to cycle back/forward through command o Use output of one command as input to n !str – repeat previous command beginning with history another – separate by a | str n left/right to edit the command line ls -ltrF | tail n !N – repeat command number N n <ctrl>-a – beginning of line n o Run a command in the background n ^old^new – repeat previous command, replacing <ctrl>-e – end of line firefox & first occurrence of old with new n Dont need to move to end of line before running Using Unix Commands Using Unix Commands Using Unix Commands o o Standard input/output/error from commands Redirecting standard input/output/error o Pipes (the vertical bar | ) (csh/tcsh) n Input – usually the keyboard ls –ltrF | tail n Output – usually the screen > >> >& >>& < << o Aliases – roll your own commands n Error – usually the screen alias ll '/bin/ls –ltrF' ls > file std output overwrites file ls >> file std output appends at end of file alias lt '/bin/ls –ltrF | tail' alias arch 'cd /bigtemp/poker/archive' ls >& file std output/error into file ls >>& file std output/error appended to file o Line Continuation character - \ ls < file std input from file ls << WORD std input until line identical to WORD [WORD must be first and only thing on the line, and unique] 6 Using Unix Commands Using Unix Commands Working with Files and Directories o Line Continuation character - \ o Shell Scripts – group of commands entered o Creating files /bin/rm –r \ one by one in a file, executed as if you had n cat – concatenate files file1 \ typed them at the prompt file2 \ cat > file1 file3 \ this text will be put into file1 file4 #!/bin/csh echo Good Morning, Pete ^D echo Today is `date` echo Remember everything you need to do cat file1 file2 file3 > file4 exit cat file1 file2 > file1 o Used extensively for creating GEMPAK plots [overwrites original file1] Working with Files and Directories Working with Files and Directories Working with Files and Directories o echo – echo commands to stdout (the screen?) o Editing files o Text editors n What is a text editor compared to a word n vi(m) - cryptic text editor included with all unix echo this text will be put processor? n nedit - graphical editor simliar to notepad into file1 > file1 n gedit - another graphical editor n pico/nano - nicer character based text editor n vi, nedit, gedit, nano, pico, emacs echo this text will be n emacs- powerful, customizable text editor appended after the last >> vi file1 o touch – update the modification time of a file, or file1 nedit file1 & create an empty file if it doesnt already exist 7 Working with Files and Directories Working with Files and Directories Working with Files and Directories o Displaying files o Listing files – ls o Copying files - cp n Cat – file scrolls up the screen cat file1 n cp file1 file2 copies file1 to file2 n Pagers (more, less) – pause between screenfuls ls n cp file1 dir1 creates a copy of file1 less file1 a b dir1 file1 in dir1 n Text editors (vi, nedit, pico, emacs) ls –a n cp file1 file2 file3 dir1 n Head – displays the first 10 lines of a file .