% CST8207 Week 11 Notes -- Shell Scripts: command substitution, integer arithmetic, exit status, debugging, if/then/else, test helper % Ian! D. Allen -- -- [www.idallen.com] % Winter 2018 - January to April 2018 - Updated 2018-04-04 23:14 EDT - [Course Home Page] - [Course Outline] - [All Weeks] - [Plain Text] C O U R S E    E V A L U A T I O N ================================== ____ _ ____ __ __ | _ \ | | ___ __ _ ___ ___ | _ \ ___ \ \ / /___ _ _ _ __ | |_) || | / _ \ / _` |/ __| / _ \ | | | | / _ \ \ V // _ \ | | | || '__| | __/ | || __/| (_| |\__ \| __/ | |_| || (_) | | || (_) || |_| || | |_| |_| \___| \__,_||___/ \___| |____/ \___/ |_| \___/ \__,_||_| ____ ____ _____ _____ _ _ _ / ___/ ___|_ _| | ____|_ ____ _| |_ _ __ _| |_(_) ___ _ __ | | \___ \ | | | _| \ \ / / _` | | | | |/ _` | __| |/ _ \| '_ \ | |___ ___) || | | |___ \ V / (_| | | |_| | (_| | |_| | (_) | | | | \____|____/ |_| |_____| \_/ \__,_|_|\__,_|\__,_|\__|_|\___/|_| |_| -    **Closes Sunday April 29.** - Feedback is anonymous. Professors are not told who said what and results are not released until after grades have been submitted. - I publish my [anonymous course evaluations], so your comments will be there to guide future students. - Listen to Dogbert on [satisfaction surveys] - The Checking Program for your assignments tells you how to turn off the nag message. Read All The Words. Readings, Assignments, Labs, Tests, and ToDo ============================================ Read (at least) these things (All The Words) -------------------------------------------- 1. [Week 11 Notes HTML] -- this file -- **Read All The Words** 2. [Command Substitution] -- interpolate stdout into a command line using `$(...)` or \`...\` 3. [Integer Arithmetic] -- shell script integer math: `expr`, `let`, `$((...))` 4. [Command Exit Status] -- variable `$?` 5. [Shell Script Debugging] -- using options `-v` and `-x` 6. [Shell Control Structures] -- if, then, else, test, `[...]`, for, case 7. Next Week: [Shell Script Problems] -- arithmetic, syntax, test, boolean, etc. 8. [List of Commands] -- Command names you should know, listed by week 9. [Video Tutorials on Lynda.com] -- tagged by week number 10. [Linux and Sysadmin News in the World] Assignments, Quizzes, and Lab work this week -------------------------------------------- > **Reminder:** There are now two quizzes that you need to complete on > Blackboard as part of your term Quiz mark. A third quiz will be posted > before the Final Exam. The Quizzes are *not* optional; see the [Course > Outline]. Check the due date for each assignment and put a reminder in your agenda, calendar, and digital assistant. Just like in the Real World, not all due dates are on the same days or at the same times. - Review last week. Did you do everything assigned last week? - [Assignment #09 HTML] -- setting permissions, mode, `umask`, personal web site - [Assignment #11 HTML] -- tar, processes, syslog, crontab, at, mail, shell script - Look for the upcoming [Assignment #12 HTML] -- shell scripts - The checking program has a feature to check just one of your scripts. - OPTIONAL: Do Bonus [Assignment #10 HTML] about Midterm #2 - There is a checking program available to check your file format for this bonus assignment, but only people who Read All These Words will know about it. Wrong file format means no marks. *Do not redirect or save the output of this checking program!* Worksheets ---------- Worksheets are preparation for your assignments. You can't do the assignments without having done the worksheets first, and you can't do the worksheets without having first read the Course Notes: 1. Read the web notes. (Please: **Read All The Words**) 2. Do the relevant Worksheet(s). 3. Do the relevant Assignment(s). Make notes from the worksheets on *how each command works*. What do the options used in the worksheets mean, for each command? (See the weekly [List of Commands].) Form a small study group to do the worksheets. Each person tries the example given, and you make sure you all get the same answers. Worksheets are not for hand-in; they are not worth marks; the assignments test your knowledge of the lectures and worksheets. > The worksheets are available in four formats: Open Office (ODT), PDF, HTML, > and Text. Only the Open Office format allows you "fill in the blanks" in > the worksheet. The PDF format looks good but doesn't allow you to type into > the blanks in the worksheet. The HTML format is crude but useful for quick > for viewing online. Do **NOT** open the Worksheet ODT files using any Microsoft products; they will mangle the format and mis-number the questions. Use the free Libre Office or Open Office programs to open these ODT documents. On campus, you can get a copy here: [Course Introduction: Install Libre Office]. Worksheet #08 is for [Assignment #09 HTML]. - [Worksheet #08 ODT] -- Linux file system permissions (modes) - This Worksheet is a prerequisite for [Assignment #09 HTML] - [Worksheet #08 PDF] -- PDF version - [Worksheet #08 HTML] -- HTML version - `chmod, ls -lid, umask` Worksheets prepare you for the upcoming assignments. Upcoming tests and exams ------------------------ This course has two midterm tests (10%, 15%) and one final exam (40%). ![Bring your favourite marker to your test] - Put these dates below into your phone! - Read the [Test Instructions] (all the words) before your tests and exam. - Use the [Algonquin Registered Name Game] link in the [Test Instructions] to confirm the spelling of your name before the test. - I don't answer questions about the instructions during the test. Ask me in a lab period before the test. - You must write the test in the lecture class in which you are registered. ### The Final Exam -- 10:30am Saturday April 28 2018 -- 40% Final Exam: Saturday April 28 10h30am (10:30am to 1:30pm; 3 hours -- 40%) in room T102A,B,C. - The Final Exam is three hours long and contains approximately 180 multiple-choice questions similar to those found in the three preceding [Practice Tests and Answers]. - Do *all three* practice tests before the Final Exam! - Three Hours! Take a bathroom break before you start the exam! All three practice tests will be posted under [Practice Tests and Answers]. The Final Exam is comprehensive of the whole course; you need to do *all three* practice tests for the Final Exam. Notes from the Classroom ======================== - **Take notes in class!** Keep a pad open on your desk. - In class I will show you how to decode the Mystery Puzzle File that is part of [Assignment #11 HTML]. Take notes! - Don't forget to finish your five Blackboard quiz attempts for each of the Midterm 1 and Midterm 2 quizzes. There is a third quiz available to prepare for the Final Exam. Do five attempts in all three quizzes. - Regarding world-writable files in your account: - Outside of the one directory in [Assignment #09][Assignment #09 HTML], you must not have any world-writable (writable by "other") files or directories in your account. - The checking program will deduct marks if it finds world-writable files. - You can find world-writable files by re-reading the "Examples of uses" in [Finding Files] from the Week 3 notes. Commands Used ------------- > Keep a notebook with a [List of Commands] in it. > > - You need to write down yourself what each command *does*. > - Check the updated list of commands each week. > - I will check for this list in your lab periods. > - Bring your notes to class! Stop wasting time looking up commands. - Are you making notes from the worksheets on how each command works? - What do the options used in the worksheets mean, for each command? - Don't copy and use options that you don't understand! Finding world-writable files in your account -------------------------------------------- The assignment **Checking Programs** may issue this message: Number of world-writable pathnames in abcd0001 account: 1 ERROR: Sysadmin do not create files that anyone can overwrite. ERROR: See "Examples of uses of find" to find these files. ERROR(-1): Fix the permissions on these files Don't create files or directories that anyone ("other") can write, except the few required ones in the one [Assignment #09 HTML] `head` directory! You must look at all the files in your account to try to find these files or directories that you have created with "other" write permissions. You can find the files the hard way, using `cd` and `ls`, or you can do it the easy way using a recursive command: - To learn how to `find` these world-writable files in your account, first use a command to search for the files that contain the text `world-writable` in all the course notes. The course notes have an example showing what command to use to find world-writable files. - To search the course notes for a text string, re-read section 4.5 of [Assignment #05 HTML], especially item #8 about searching for the text string `Filezilla` in all the course notes. - You will be able to identify which course notes web page you should read to find the example showing how to find world-writable files. - Fix the permissions on these files. Remove write permission for "other". Your own personal web page on the CLS ===================================== - View [all the Winter 18W class images] Who is using the VIM editor? ============================ This page may take a minute or two to load; be patient: [Who is using the VIM editor?] Tutoring ======== Many students find that hiring a personal tutor helps them get through the first term. Financial assistance is available. See the **Tutoring** heading in the [Course Introduction]. SSH Attacks on the CLS ====================== You are not paranoid if they really are out to get you! See the [Week 03 Notes HTML] for command pipelines to count the SSH attacks on the CLS. Locked out of the CLS ===================== When you are locked out, [follow the directions] in the notes to get your IP address re-enabled. ![Take Notes in Class] -- | Ian! D. Allen, BA, MMath - 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 [www.idallen.com]: http://www.idallen.com/ [Course Home Page]: .. [Course Outline]: course_outline.pdf [All Weeks]: indexcgi.cgi [Plain Text]: week11notes.txt [anonymous course evaluations]: /#coursenotes [satisfaction surveys]: http://dilbert.com/strips/comic/2005-04-07/ [Week 11 Notes HTML]: week11notes.html [Command Substitution]: 710_command_substitution.html [Integer Arithmetic]: 715_shell_arithmetic.html [Command Exit Status]: 720_exit_status.html [Shell Script Debugging]: 725_debugging_shell_scripts.html [Shell Control Structures]: 730_control_statements.html [Shell Script Problems]: 740_script_problems.html [List of Commands]: 900_unix_command_list.html [Video Tutorials on Lynda.com]: 910_lynda_index.html [Linux and Sysadmin News in the World]: 950_linux_world.html [Assignment #09 HTML]: assignment09.html [Assignment #11 HTML]: assignment11.html [Assignment #12 HTML]: assignment12.html [Assignment #10 HTML]: assignment10.html [Course Introduction: Install Libre Office]: 050_course_introduction.html#install-libreoffice-or-openoffice-into-windows [Worksheet #08 ODT]: worksheet08.odt [Worksheet #08 PDF]: worksheet08.pdf [Worksheet #08 HTML]: worksheet08.html [Bring your favourite marker to your test]: data/sniff_markers.jpg "Bring your favourite marker to your test" [Test Instructions]: 000_test_instructions.html [Algonquin Registered Name Game]: http://cst8207.idallen.ca/~idallen/namegame.cgi [Practice Tests and Answers]: PRACTICE_TEST_README.html [Finding Files]: 180_finding_files.html [Assignment #05 HTML]: assignment05.html [all the Winter 18W class images]: http://cst8207.idallen.ca/montage18w.cgi [Who is using the VIM editor?]: http://cst8207.idallen.ca/vim18w.cgi [Course Introduction]: 050_course_introduction.html [Week 03 Notes HTML]: week03notes.html [follow the directions]: 070_course_linux_server.html#getting-locked-out-of-the-server [Take Notes in Class]: data/remember.jpg "Take Notes in Class" [Pandoc Markdown]: http://johnmacfarlane.net/pandoc/