% Week 07 Notes for CST8207 - Fall 2012 % Ian! D. Allen - idallen@idallen.ca - www.idallen.com % Fall 2012 - September to December 2012 - Updated Sun Oct 21 23:32:33 EDT 2012 Course Linux Server repairs =========================== See the [CST8207 Blackboard Announcements] (also sent to your [Algonquin EMail]) for news regarding the Course Linux Server repairs. Readings, Assignments, Labs, and ToDo ===================================== - Read (at least) these things (All The Words): - [Week 07 Notes HTML] - [Shell Variables - Basics (non-scripting)] - [Unix/Linux Shell Command Line Quoting Mechanisms] - [Unix/Linux File System - (correct explanation)] - [Hard links and Unix file system nodes (inodes)] - [List of Commands] - Read (All The Words), Do, and Save (but not for hand-in): - Have you completed all the worksheets to date? - Quizzes will ask you about your answers in your saved worksheets. - Read (All The Words), Do, and then Submit via Blackboard: - Optional Bonus: [Assignment #06] - **READ ALL THE WORDS** Lecture Notes for This Week =========================== - Review last week. Did you do everything assigned last week? - Send me the Rap video! If you license it for public view, I’ll post it. - videos published: [CST8207 Rap Videos] - any more? From the Class Notes link on the Course Home Page ------------------------------------------------- - [Shell Variables - Basics (non-scripting)] - [Unix/Linux Shell Command Line Quoting Mechanisms] - [Unix/Linux File System - (correct explanation)] - [Hard links and Unix file system nodes (inodes)] - [List of Commands] From the Classroom Whiteboard/Chalkboard ---------------------------------------- - See the Class Notes for a sample of the output you should have generated for Assignment 4. ### Your in-class notes go here - take notes in class! The command that creates new names for existing files is **`ln`** (link): $ ln source target Know the meaning of each of the output fields of **`ls -dils`**: 2 4 drwxr-xr-x 24 root root 4096 Sep 12 12:12 / 2883589 4 drwxr-xr-x 2 root root 4096 Oct 5 02:05 /bin 2883666 104 -rwxr-xr-x 1 root root 105776 Feb 23 2011 /bin/ls 2883587 12 drwxr-xr-x 186 root root 12288 Oct 17 13:38 /etc 2889578 4 -rw-r--r-- 1 root root 2209 Mar 19 2012 /etc/passwd 1. inode number 2. size in disk blocks 3. (one char) type (file, directory, symlink, etc.) 4. (9 chars) permissions (3 for user, 3 for group, 3 for other) 5. link count (count of names for this inode) 6. userid of owner 7. userid of group 8. size in bytes (characters) 9. date last modified 10. name If two names reference the same inode, all the above attributes (except the name) will and must be identical for the two names. All the above attributes, except the name, are stored with the inode itself. The names are stored in directories. ### I’ve been telling you some simplification lies - Lie: Names are stored with the things they name. - Truth: Names and inode numbers are stored in directories. - Lie: the **`rm`** command removes files. - Truth: The **`rm`** command only removes **names**. When all the names are gone, only then are the file data blocks released. - Lie: All file system objects have a unique inode. - Truth: All things *on the same file system (disk partition)* have a unique inode. Different file systems have separate disk space and inode trees, so the same inode number will mean different file system objects in *different file systems*. You can’t hard link objects between different file systems. (Use symbolic links instead.) Real Sysadmin Work ================== Ubuntu Linux on your Phone ========================== ![SSH Terminal on Phone] ![Ubuntu Desktop on Phone] See also [Ubuntu on Phone] for more screen shots. -- | Ian! D. Allen - idallen@idallen.ca - Ottawa, Ontario, Canada | Home Page: http://idallen.com/ Contact Improv: http://contactimprov.ca/ | College professor (Free/Libre GNU+Linux) at: http://teaching.idallen.com/ | Defend digital freedom: http://eff.org/ and have fun: http://fools.ca/ [Plain Text] - plain text version of this page in [Pandoc Markdown] format [CST8207 Blackboard Announcements]: http://blackboard.algonquincollege.com/webapps/blackboard/content/launchLink.jsp?course_id=_124970_1&tool_id=_1604_1&tool_type=TOOL&mode=cpview&mode=reset [Algonquin EMail]: https://liveac.algonquincollege.com/ [Shell Variables - Basics (non-scripting)]: 430_shell_variables.html [Unix/Linux Shell Command Line Quoting Mechanisms]: 440_quotes.html [Unix/Linux File System - (correct explanation)]: 450_file_system.html [Hard links and Unix file system nodes (inodes)]: 460_links_and_inodes.html [List of Commands]: 900_unix_command_list.txt [CST8207 Rap Videos]: 000_Rap.html [SSH Terminal on Phone]: data/ubuntuphone/ubuntuphone1.jpg "SSH Terminal on Phone" [Ubuntu Desktop on Phone]: data/ubuntuphone/ubuntuphone2.jpg "Ubuntu Desktop on Phone" [Ubuntu on Phone]: data/ubuntuphone/ [Plain Text]: week07notes.txt [Pandoc Markdown]: http://johnmacfarlane.net/pandoc/