Some History The original SpaceWar game (sometimes spelled Space War or Spacewar!) was created in1962 on the PDP-1 computer at MIT. Unix Computing Environment First computer to have a CRT display and a keyboard. SpaceWar was not only the first game ever made, but also did several other things: The first controller for SpaceWar was a trackball, essentially making it the first mouse. In 1969, Ken Thompson wanted to play SpaceWar of a PDP-8 computer, so he wrote an operating system called UNIX to get it running. 1 CIT593 2 Unix Linux Generic name for a type of operating system(OS) Linux (a.k.a GNU) is similar to Unix First version in 1969 by Ken Thompson by AT&T Bell Laboratories Multiuser and interactive; ppgrogressive for its time However it is not proprietary OS like Windows or Solaris Is written mostly in ‘C’, and a little bit in assembly Users can obtain it freely, modify it and redistribute freely Has been ported to many different processors Open Source Two basic versions have evolved Derived from Unix System V (owned by AT&T) Most nonnon--windowswindows labs in CIS are Linux Derived from Berkeley Software Distribution , or BSD In 1980’s, SunOS branched out from BSD Recent versions of SunOS are called SolarisTM CIT593 3 CIT593 4 1 Shell Shell (contd..) Shell provides user interface between OS and user Several different shells exist Thus Unix/Linux is command driven Grappghical User Interface also exist e.g. KDE Bash is popular w/ Linux Default shell upon login in Linux machines is bash shell Can use csh (pronounced “sea shell”) shell Command interpreter with syntax similar to C language Enhanced version is tcsh (t = tenextenex)) kernel ¾ allows step up/down through history list using arrow keys ¾ Completes file/directory search with ‘tab’ key To switch from bash mode to csh/tcsh: type “csh/tcsh” at prompt CIT593 5 CIT593 6 File System File Permissions After entering: ls In UNIXUNIX--basedbased systems, files are organized into a 'tree' Desktop mail Maildir public_html html Mail structure. In this tree,,, there is a 'root,' which is a directory that After entering: ls -ll contains every other directory on the system. drwxr-xr-x 2 username username 4096 2006-09-04 06:51 html lrwxrwxrwx 1 username username 4 2006-08-30 09:21 mail -> Mail Other directories, which are 'branches' of the tree. drwxr-xr-x 3 username username 4096 2006-09-04 06:50 Mail drwxrwx--- 2 username username 4096 2006-08-30 09:21 Maildir root (/) lrwxrwxrwx 1 username username 4 2006-08-30 09:21 public_html -> html bin src home1 usr “d” = Directory /File name directory/folder size Date & Time p java palsetia CIT593 shellcmds.ppt 7 CIT593 8 2 File Permissions(contd..) chmod commands drwxrdrwxr--xx------ 6 palsetia palsetia 4096 20062006--0909--0404 06:52 CIT593_f06 After entering ls ––ll in my home directory, I see: drwxr-xr-x 2 palsetia palsetia 4096 2006-09-04 06:51 html lrwxrwxrwx 1 palsetia palsetia 4 2006-08-30 09:21 mail -> Mail drwxr-x--- 6 palsetia palsetia 4096 2006-09-04 06:52 CIT593_ f06 drwxr-xr-x 3 palsetia palsetia 4096 2006 -09-04 06:50 Mail drwxrdrwxr--xrxr--xx 2 palsetia palsetia 4096 20062006--0909--0404 06:51 html lrwxrwxrwx 1 palsetia palsetia 4 2006-08-30 09:21 public_html -> html lrwxrwxrwx 1 palsetia palsetia 4 20062006--0808--3030 09:21 mail -->> Mail drwxrdrwxr--xrxr--xx 3 palsetia palsetia 4096 2006-2006-0909--0404 06:50 Mail chmod 700 filename user can read, write and execute 0 : 000 : --- world 8 2 world chmod 600 filename 18 : 0012 : --x group 2 : 010 : -w- ggproup user user can read and write 8 2 3 : 011 : -wx user r = read permission 8 2 chmod 500 filename 4 : 100 : r-- w = write permission user can read and execute 8 2 5 : 101 : r-x x = execute permission chmod 755 filename 8 2 68 : 1102 : rw- for publishing on the web 78 : 1112 : rwx CIT593 9 CIT593 10 About files Shell Commands for Handling files Text files can be displayed, edited or printed file filename contain only ASCII characters up to 12710, including a few allowed Attempts to report on whether the file is text or binary control chars (e.g. !, & etc.) divided into lines; en d of lin e m ark ed by a co nt ro l c ha racter acte a C source file is an example of a text file cat filename not useful for binary files Binary files attempts to display the file on the terminal contain arbitrary bit patterns; do not print or display! if file longer than 25 lines, top part may scroll off cat filename | more Executable file display a text file (piped through the pager program, more) a binary file; cannot be displayed or printed by the usual means this shows you 25 lines at a time press any key to get more line od – x filename displays a file (text or binary) as hex byte values CIT593 11 CIT593 12 3 Text Editors ssh There are many editors Secure Shell or SSH is a network protocol that allows NonNon--graphicalgraphical (open in the terminal) data to be exchanged using a secure channel between two networked devices ¾ Pico, Nano,,, Vim, Vi ¾ Emacs Basically encrypts data which earlier protocols such as telnet left data to be intercepted easily Graphical Your accounts are on eniac server ¾ Emacs (We will use this for class) Command: emacs filename & Eniac account is also mounted on Linux PC’s From an existing shell, log into eniac using your ¾ KEdit username ssh eniac.seas.upenn.edu OR ssh [email protected] CIT593 13 CIT593 14 Archive Utility Settings: .cshrc /.bashrc .cshrc/.bashrc UNIX archive utility commands gets executed anytime you start up type of shell Zip This where one would change there environment settings or define shortcuts or preference Archive: zip -r myZipFile.zip file1 file2 file3 ... fileN View contents: zip ––vv myZipFile.zip Extract: unzip myZipFile.zip To view files starting with “.” ls –al list all the files/directories in your home directory tar Archive: tar -cvf tarfile.tar file1 file2 ….file N sour ce . cshr c/. bashr c View Con ten ts: tar -tvf tfilttarfile.tar re-executes your .cshrc file (at your request) Extract: tar -xvf tarfile.tar v=verbose, x=extract, f=file, t=table of contents, c= create CIT593 15 CIT593 16 4 Example of a Preferences/ Setting Edit ..cshrccshrc/./.bashrcbashrcto perform your settings: To c reate s ho rtcuts use aaaslias comma nd Shortcut for emacs ¾ Bash: alias e=‘emacs’ ¾ Csh: aliac e emacs Shortcut for clear (clear command clears the screen) ¾ Bash: alias c=‘ clear’ ¾ Csh: alias c clear CIT593 17 5.