Linux vi and Scala 8 30 2010 Opening Discussion Have you come up with any new questions about class Today is a test run on IcPs but I want to start getting people into the flow Minute Essays Why do we use Linux What happens if very few people come back for the second semester Will you be in trouble if you haven t done any programming previously Reading before or after Linux Go ahead and log in Linux is just another OS like Windows or Mac OS Linux is primarily used in servers Efforts are being put into making it a desktop OS It has a GUI but we will focus on doing things through the command line Bring up a terminal Change password with passwd Command Line You are likely used to the point and click interface of a GUI To run a program you double click on it or a file associated with it Any other information has to be given after the program opens With the command line you type in the name of the program you want to run You can also specify any other information you want through command line arguments Files and Directories What you call folders were originally directories Commands pwd See current directory ls List the contents of a directory mkdir rmdir Make and remove directories cp mv rm Copy move remove files less more cat See contents of files Tips Tab completion for file directory names for last matching command Ctrl r to search your history The man command for manual entries Use the k option to search Permissions Do ls with l option to see permissions Sets of rwx for user group and others Use whoami and groups to find identity Use chmod and chown to change permissions or ownership Remote Use ssh to login into one machine from another Use scp to copy files from one machine to another The website has a link to Putty which will give you these abilities from Windows Other du Lists disk usage grep Searches for something inside of files find Find files head List the first several lines of a file tail List the last several lines of a file top Look at what is running on a machine w Look at who is logged into a machine I O Redirection You can send a programs output to a file using or You can make a program use a file as input using You can do more interesting things by sending the output of one program to another with Text Files Editors Programs are typically written as plain text files and should be edited with a text editor Notepad is a basic text editor on Windows Word is NOT a text editor Some text editors are better than others for programming In this class we will use vi vi The vi editor is standard on Linux which is one reason we like to use it It is also good for programming Has modes Start in command mode You type in an edit mode i insert I insert at beginning of line a append A append at end of line R replace characters Other Commands x delete characters dd delete lines yy yank copy lines p or P paste before or after r replace a single character J join lines and n search for something and next cw change a word repeat last command u and Crtl r Undo and redo Scala Script First Program Let s make a directory and use vi to write our first Scala program then run it The standard first program is Hello World and I don t want to break with tradition Minute Essay What are your first impressions of command line Interclass problem Make a directory called IcP in your home directory and edit a file in it that
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