% CST8207 Assignment 11 – tar, syslog, processes, mail, crontab, at % Ian! D. Allen – – [www.idallen.com] % Winter 2015 - January to Apil 2015 - Updated Mon Mar 30 11:06:25 EDT 2015 Due Date and Deliverables ========================= > **Do not print this assignment on paper!** > > - On paper, you will miss updates, corrections, and hints added to the > online version. > - On paper, you cannot follow any of the [hyperlink URLs] that lead you > to hints and course notes relevant to answering a question. > - On paper, scrolling text boxes will be cut off and not print properly. - **Due Date**: `15h00 (3pm) Tuesday March 31, 2015 (start of Week 12)` - Late assignments or wrong file names may not be marked. Please be accurate and punctual. - **Available online** - Version 1 – 17:00 March 22, 2015 - **Prerequisites** - All [Class Notes][hyperlink URLs] since the beginning of term. - All your previous [Assignments] and [Worksheets]. - An ability to **READ ALL THE WORDS** to work effectively. - **Deliverables** 1. One plain text file uploaded to Blackboard according to the steps in the [Checking Program] section below. 2. Directory structure and files created and left for marking on the [Course Linux Server] (**CLS**).\ **Do not delete any assignment work from the CLS until after the term is over!** **WARNING:** Some inattentive students upload Assignment #11 into the Assignment #10 upload area. Don’t make that mistake! Be exact. Purpose of this Assignment ========================== > **Do not print this assignment on paper!** On paper, you cannot follow any > of the hyperlink URLs that lead you to hints and course notes relevant to > answering a question. This assignment is based on your weekly [Class Notes]. 1. Working with `tar` archives from [Package Management] 2. Working with [Processes and Jobs] 3. Working with [System Log Files] 4. Using the [Crontab and At Job Schedulers] (`cron` and `at`) 5. [Sending EMail] and [Reading EMail] on the CLS. Remember to **READ ALL THE WORDS** to work effectively and not waste time. Introduction and Overview ========================= This is an overview of how you are expected to complete this assignment. Read all the words before you start working. For full marks, follow these directions exactly. 1. Complete the **Tasks** listed below, in order, and don’t skip steps. 2. Verify your own work before running the **Checking Program**. 3. Run the **Checking Program** at the end of the task to help you find errors. 4. Submit the output of the **Checking Program** to Blackboard before the due date, following the directions given below. 5. **READ ALL THE WORDS** to work effectively and not waste time. Notes on checking your work --------------------------- 1. You will create file system structure in your CLS home directory containing various directories and files. When you are finished the tasks, leave the files and directories in place on the CLS as part of your deliverables. Assignments may be re-marked at any time on the CLS; you must have your term work available on the CLS right until term end. **Do not delete any assignment work until after the term is over!** 2. You can use the **Checking Program** to check your work **after** you have completed each task. Most task sections below require you to **finish the whole task section before running the Checking Program**; you may not always be able to run the **Checking Program** successfully in the middle of a task or after every single task sub-step. 3. You can modify your work and check it with the **Checking Program** as often as you like before you submit your final mark. You can submit your mark as many times as you like before the due date. > Since I also do manual marking of student assignments, your final mark may > not be the same as the mark submitted using the current version of the > **Checking Program**. I do not guarantee that any version of the **Checking > Program** will find all the errors in your work. Complete your assignments > according to the specifications, not according to the incomplete set of the > mistakes detected by the **Checking Program**. The Source Directory -------------------- All references to the **Source Directory** below are to the CLS directory `~idallen/cst8207/15w/assignment11/` and that name starts with a *tilde* character `~` followed by a user name with no intervening slash. The leading tilde indicates to the shell that the pathname starts with the HOME directory of the account `idallen` (seven letters). You do not have permission to list the names of all the files in the Source Directory, but you can access any files whose names you already know. Searching the course notes on the CLS ------------------------------------- All course notes are available on the Internet and also on the CLS. You can learn about how to read and search these CLS files using the command line on the CLS under the heading *Copies of the CST8207 course notes* near the bottom of the page [Course Linux Server]. Tasks ===== - Do the following tasks in order, from top to bottom. - These tasks must be done in your account on the [Course Linux Server]. - **READ ALL THE WORDS!** and do not skip steps. - Run the **Checking Program** to grade your work, then upload the file containing the output of the **Checking Program** to Blackboard. - Your instructor will also mark on the due date the work you do in your account on the CLS. Leave all your work on the CLS and do not modify it. - **Do not delete any assignment work from the CLS until after the course is over.** Set Up – The Base Directory on the CLS -------------------------------------- > You must keep a list of command names used each week and write down what > each command does, as described in the [List of Commands You Should > Know]. Without that list to remind you what command names to use, you > will find assignments very difficult. 1. Do a [Remote Login] to the [Course Linux Server] (**CLS**) from any existing computer, using the host name appropriate for whether you are on-campus or off-campus. 2. Make the CLS directory `~/CST8207-15W/Assignments/assignment11` in which you will create the files and scripts resulting from the following tasks. 3. Create the `check` symbolic link needed to run the **Checking Program**, as described in the section [Checking Program] below. **This `assignment11` directory is called the [Base Directory] for most pathnames in this assignment. Store your files and answers in this [Base Directory], not in your HOME directory or anywhere else.** Use the symbolic link to run the [Checking Program] to verify your work so far. Part A – Disk Usage, `tar` Archive and Listing ---------------------------------------------- You need to know [Disk Usage] and [Package Management] to do this task. 1. Make your [Base Directory] your current directory and do not change directories for this task. All recorded pathnames must be relative to the [Base Directory]. ### `3maze` {#maze .floatright .unnumbered} ### *abcd0001* {#abcd0001 .floatright .unnumbered} 2. In the current directory (the [Base Directory]), create a directory named `3maze`. Without changing directories, create a symbolic link in that `3maze` directory that is the name of your 8-character CLS userid. The symlink should point to the absolute path of the `maze` directory that is in the [Assignment #03] **Source Directory**. The symbolic link will have a size of exactly 43 characters (the absolute path of the `maze` directory), e.g. for userid *abcd0001* the symlink long listing would start like this: lrwxrwxrwx 1 abcd0001 abcd0001 43 Mar 22 12:03 3maze/abcd0001 -> The rest of the symlink is the absolute path of the `maze` directory. You probably have it right if `ls 3maze/abcd0001` shows about 1700 (non-hidden) pathnames from the maze. 3. Display the sum total of disk blocks in the hidden `3maze/abcd0001/.0` sub-directory inside the maze. - Use your *own* userid, not *abcd0001* - The number printed should be larger than 6100. - The relative pathname beside the number should be exactly as given. - You will need this exact relative pathname in the next questions. ### `mazeblocks.txt` {#mazeblocks.txt .floatright .unnumbered} 4. Put the above one-line of output (the number of disk blocks) into a new file `mazeblocks.txt` in the `3maze` directory. - The file will be one line long, containing two words: a number larger than 6100 and a relative pathname containing two slashes. ### *YYYYMMDD*`.tar.gz` {#yyyymmdd.tar.gz .floatright .unnumbered} 5. Create a *gzip*-style compressed `tar` archive in the `3maze` directory containing the contents of the `.0` directory from above. Use the relative pathname from above as the source of the files to archive. Name the new archive *YYYYMMDD*`.tar.gz` (no spaces) under `3maze`, where *YYYYMMDD* is the numeric year-month-day date of the final exam in this course. - The *gzip*-style compressed archive will be approximately 20000 bytes. - All the pathnames in the `tar` archive file must be relative paths with `3maze/abcd0001/.0/` at the beginning of every name. ### *YYYYMMDD*`.tar.bz2` {#yyyymmdd.tar.bz2 .floatright .unnumbered} 6. Create a *bzip2*-style compressed `tar` archive in the `3maze` directory of the same `.0` directory from above. Use the same name as for the *gzip* archive, but use the file extension `.bz2` instead of the `.gz` extension. - The *bzip2*-style compressed archive will be approximately 6600 bytes. 7. Look up the option to `ls` that gives “the allocated size of each file, in blocks” and use that option (and only that option) to display the size and name of the two `tar` archives you just created in the `3maze` directory. - The output will be one line long, four words, with each tar archive name preceded by its size in blocks. - A GLOB pattern will be helpful to generate the two archive pathnames in the `3maze` directory. ### `mazeblocks.txt` {#mazeblocks.txt-1 .floatright .unnumbered} 8. Append the output of the above command line (the sizes and relative pathnames) to the disk blocks file you created earlier. The file will now be three lines (six words) long. - Note how the output of `ls` changes to separate lines when output is to a file instead of directly to your screen. This is one of the few commands that does this. - Look at the three lines in the disk blocks file and note how the compressed `tar` archives are much smaller (fewer disk blocks) than the original disk space used. - Note how the newer *bzip2* compression algorithm is much better at compressing this file (fewer disk blocks) than the older *gzip* algorithm. **Hint:** Go back and re-read the first step in this task if you don’t have the right pathnames in your output. ### `tar_tvzf.txt` {#tar_tvzf.txt .floatright .unnumbered} 9. Generate a verbose listing of your *gzip*-style `tar` archive file, showing the contents of the archive including all the owners and date/time stamps, but don’t display it directly on your screen since it’s over 1,500 lines long. Save just the first five and last five lines of the verbose listing into file `tar_tvzf.txt` under `3maze` directory. The file word count will be `10 60 751` and the first line and last line should look like this (where *abcd0001* is replaced by your userid): drwxr-xr-x idallen/idallen 0 2012-02-13 13:33 3maze/abcd0001/.0/ drwxr-xr-x idallen/idallen 0 2012-02-13 13:33 3maze/abcd0001/.0/.1/.1/.1/ **Hint:** You will need to use one command pipeline to generate the first five lines into the output file, and a second command pipeline to generate the last five lines and append them to the output file to make a total of ten lines in the file. 10. The *bzip2* compression algorithm is better than the *gzip* compression algorithm; *bzip2* produces smaller compressed files. Answer this question: **True or False:** Because *bzip2* is smaller than *gzip*, generating the verbose table of contents of the *bzip2*-style `tar` archive file will produce fewer lines than the table of contents of the *gzip*-style archive. Append your one-word answer `true` or `false` to the `tar_tvzf.txt` file. (The file will now contain 11 lines.) (The checking program will not check this answer. Your instructor will check the answer and mark it after you hand in your assignment.) Run the [Checking Program] on the CLS to verify your work so far. If you have errors, go back and re-read the first step in this task. Part B – Process Listing ------------------------ You need to know [Processes and Jobs] to do this task. ### `psbsd.txt` {#psbsd.txt .floatright .unnumbered} 1. Place a full list of all processes for all users, **BSD** format, all users, text user name (not numeric UID), full wide listing (not truncated at all), into file `psbsd.txt` in your [Base Directory]. It should be at least 105 lines and 9KB. The header line and one of the very long lines will be a `dhclient` line similar to this (use a text-searching command to find it in the output): USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 4078 0.0 0.0 7264 388 ? Ss Mar15 0:00 dhclient3 -e IF_METRIC=9999 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -1 eth0 ### `psunix.txt` {#psunix.txt .floatright .unnumbered} 2. Place a full list of all processes for all users, **UNIX** (System V) format, text user name (not numeric UID), full wide listing (not truncated at all), into file `psunix.txt` in your [Base Directory]. It should be at least 105 lines and 7KB. The header line and one of the very long lines will be a `dhclient` line similar to this (use a text-searching command to find it in the output): UID PID PPID C STIME TTY TIME CMD root 4078 1 0 Mar15 ? 00:00:00 dhclient3 -e IF_METRIC=9999 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -1 eth0 ### `mine.txt` {#mine.txt .floatright .unnumbered} 3. Pick off the first line (the header line) of the `psbsd.txt` file and put the one line into file `mine.txt`. (`1 11 73 mine.txt`) - There is a command that can do this easily. - Make sure you pick the header line from the right file. 4. Find all lines in `psbsd.txt` that contain your userid anywhere in the line and append those lines to the `mine.txt` file. (Some of the lines in this file may be very long.) ### Hiding command names: `vi thesis` You need to know about [Job Control and Background Processes] to do this section. We will now create a symbolic link named `vi thesis` that will run a command that has a different name. The `ps` command will show the `vi thesis` name of the symlink, not the name of the program that is the target actually being run. Users or attackers may use this symlink trick to hide the actual name of a command that they are using. ### `vi thesis` {#vi-thesis .floatright .unnumbered} 5. Create a symbolic link named `vi thesis` in your [Base Directory] that points to (has as a target) the absolute pathname of the system `sleep` command. - **Hints:** You need to find which absolute pathname the shell uses to run the `sleep` command name. See “Commands related to PATH” in [Search Path]. You need to remember how to create a [Symbolic Link]. 6. Confirm that your symlink is working by running a checksum on the `vi thesis` name and making sure it prints the same checksum number as a checksum of the real `sleep` program file. - If you see `vi thesis: No such file or directory`, you didn’t get the symbolic link correct. - If you see `vi: No such file or directory`, you forgot to hide the blank in the name from the shell. See [Quoting]. 7. Run your new `vi thesis` command (that name is in the current directory) as a background job with a single argument of `999` (that the command will interpret as a number of seconds to sleep). Your shell will print a shell background job number and process ID similar to: `[1] 12345` **Hints:** You need to remember how to execute a command in the current directory, and how to run a job in the background. You need to know how to hide blanks (in the command name) from the shell. If you got the symlink correct, you can use the TAB key to ask the shell to complete the command name in the current directory. You do not need any “seconds” qualifier on the `999` number; the number defaults to seconds. If you create more than one background job, the job number will be bigger than `[1]`. ### `thesis.txt` {#thesis.txt .floatright .unnumbered} 8. Confirm that your `vi thesis` command is running by asking the shell for a listing of jobs of the shell that includes the process ID of the jobs. It will look similar to this (note the process ID is included by using an option): [1]+ 12345 Running ./vi\ thesis 999 & Redirect the above output (showing the PID number) into file `thesis.txt` in your [Base Directory]. If you have more than one background job, the job numbers will be bigger than `[1]`. 9. Run the `ps` command and you should see output similar to this: PID TTY TIME CMD 12345 pts/5 00:00:00 vi thesis 15000 pts/5 00:00:00 ps 22460 pts/5 00:00:00 bash Note the `vi thesis` command, which is really `sleep`, and could be made to be any command you like if you change the symlink target. (The command name shown by `ps` is not necessarily accurate.) 10. Append the above `ps` output to your `thesis.txt` file. The file will have at least five lines in it. 11. Kill the job, using the special shell syntax for its job number. When you next push the `[Enter]` key, you should see: `[1]+ Terminated ./vi\ thesis 999` If you have more than one background job, the job numbers will be bigger than `[1]`. Run the [Checking Program] on the CLS to verify your work so far. Part C – System Log Files ------------------------- You need to know [System Log Files] to do this task. ### `syslog.txt` {#syslog.txt .floatright .unnumbered} 1. What is the actual name of the **syslog** program on the CLS? Search for and extract the one line from each file `psbsd.txt` and `psunix.txt` that contains this name and redirect the results (two lines, one from each file) into file `syslog.txt`. (The result will be 2 lines, 21 words.) ### `authlog.txt` {#authlog.txt .floatright .unnumbered} 2. The system authentication log file is named `auth.log` in the system log directory. Generate an `ls` long listing showing inode number of this file using the full absolute pathname, and put the results of the `ls` (the output of `ls`) into file `authlog.txt`. (The result of the `ls` command should be 1 line, 9 words, at least 60 characters.) (Optional: You may find it convenient to set a shell variable to this absolute pathname, so that you can use the short variable name rather than the long absolute pathname in the rest of these exercises. Or, you could make a short symbolic link to this file.) ### `id.txt` {#id.txt .floatright .unnumbered} 3. Use one command name to put a list (one line) of your numeric UID, your userid, your numeric GID, your group name, and your additional group names into the file `id.txt`. The result will be 1 (long) line, 3 words. See [Permissions] for the command to use to do this. Do not edit the output of the command. ### `myperms.txt` {#myperms.txt .floatright .unnumbered} 4. Look at the contents of the `id.txt` and `authlog.txt` files. Note that your account is in a group that matches the group of the system `auth.log` file, giving you **group permissions** on this file. Using a text editor, put the matching group name, the symbolic group permissions (three characters), and the octal group permissions (one digit), onto three lines in file `myperms.txt`. (The result will be 3 lines, 3 words, 10 characters. Do you remember why a file containing seven alphanumeric characters on three lines is counted as a 10-character file on Linux? Review [Line End Differences].) ### `authhead.txt` {#authhead.txt .floatright .unnumbered} 5. The system `auth.log` file contains (March 2015) over 2,222,310 lines. Use a command to extract just the first line (one line) from the head of this file and redirect that one line into new file `authhead.txt`. (The result will be 1 line 14 words 111 chars.) The time and date at the start of this line is when this copy of the log file was started. ### `failedpass.txt` {#failedpass.txt .floatright .unnumbered} 6. If you count the number of lines in the system `auth.log` containing the exact text string `Failed password`, the count is more than 7,820 lines (March 2015). Of those lines (the lines containing that exact text string), extract just lines 100 through 110 (inclusive) and put only those lines into file `failedpass.txt`. The word count for the file will be `11 174 1279`. Every line should contain the exact text string somewhere. Run the [Checking Program] on the CLS to verify your work so far. Part D – Crontab ---------------- You need to know [Crontab and At Job Schedulers] to do this task. Re-read the [Notes on checking your work] before you continue. ### `crontab.txt` {#crontab.txt .floatright .unnumbered} 1. Create a personal `crontab` entry that uses a command to update the (access and) modification time on file `crontab.txt` in your [Base Directory] (not in your `HOME` directory) every minute of every day. Use the shortest relative pathname to your `crontab.txt` file. Do not use an absolute pathname. Verify that the time of the file changes every minute. **Hints:** If it doesn’t work, read your Linux EMail for EMail messages from the **Cron** daemon showing possible errors. See [Reading EMail] for help. The single working `crontab` line should be seven words: five for the date/time, a command name, and a relative file name. ### `crontab1.txt` {#crontab1.txt .floatright .unnumbered} 2. List your personal `crontab` (one entry, with perhaps some comment lines) and redirect the output into file `crontab1.txt` in your [Base Directory]. This entry should run every minute. 3. Delete your personal `crontab` (the one that runs every minute). ### `crontab.txt` {#crontab.txt-1 .floatright .unnumbered} 4. Create a personal `crontab` entry that redirects the current date and time into the same file `crontab.txt` at [The Crontab Time]. Also use a relative pathname, not an absolute pathname. ### `crontab2.txt` {#crontab2.txt .floatright .unnumbered} 5. List your personal `crontab` (one entry, with perhaps some comment lines) and redirect the output into file `crontab2.txt`. Do not delete this personal `crontab` entry; leave it for marking. Make sure your displayed `cron` job is scheduled at [The Crontab Time]. Run the [Checking Program] on the CLS to verify your work so far. Re-read the [Notes on checking your work] if you are trying to check your work in the middle of a task instead of at the end of a task. Part E – At Job Reminder ------------------------ You need to know [Crontab and At Job Schedulers] to do this task. 1. Create an `at` job that prints the list of users on the system, one per line, at [The Crontab Time] in the year 2016. You can use any of several commands to show the list of users one per line; see the [List of Commands You Should Know]. **Hints:** You need to get the order of the date correct on the `at` command line; see the [Crontab and At Job Schedulers] course notes or RTFM to find out how to specify both a time and a date for an `at` job. No pipes are needed for this `at` job; it’s just one command name. 2. Display your list of `at` jobs to confirm the correct scheduling date and time in 2016. 3. Create an `at` job that runs the command that prints the name of this computer at [The Crontab Time] in the year 2016. **Hints:** You used this same command name in an assigment shell script recently. 4. Create an `at` job that echoes the one line of text `Exam 11am Today` to your Algonquin Live EMail account at 1 AM on the date of your final exam in this course. The EMail message sent at 1am must have the exact three-word echo text and exact five-word subject: `CST8207 Final Exam 11AM Today` **Hints:** A pipe will be needed to connect the one-line output of `echo` with the standard input of the mail program. See [Sending EMail] for help in sending EMail with a subject line. Did you use the exact words given to you for the echo and Subject texts? 5. Check the queue of `at` jobs and make sure the scheduled times are correct. 6. Delete the `at` job that shows the list of users. ### `atjob.txt` {#atjob.txt .floatright .unnumbered} 7. Display both your queued `at` jobs and redirect the output into file `atjob.txt`. You will only have two jobs – two lines. If you have more than two lines, delete the other jobs. 8. Leave these two jobs queued on the CLS for marking. Run the [Checking Program] on the CLS to verify your work so far. When you are done ----------------- That is all the tasks you need to do. Read your CLS Linux EMail and remove any messages that may be waiting. See [Reading EMail] for help. Check your work a final time using the [Checking Program] below and save the standard output of that program into a file as described below. Submit that file (and only that one file) to Blackboard following the directions below. When you are done, log out of the CLS before you close your laptop or close the PuTTY window, by using the shell `exit` command: $ exit Checking, Marking, and Submitting your Work =========================================== **Summary:** Do some tasks, then run the **Checking Program** to verify your work as you go. You can run the **Checking Program** as often as you want. When you have the best mark, upload the single file that is the output of the **Checking Program** to Blackboard. > Since I also do manual marking of student assignments, your final mark may > not be the same as the mark submitted using the current version of the > **Checking Program**. I do not guarantee that any version of the **Checking > Program** will find all the errors in your work. Complete your assignments > according to the specifications, not according to the incomplete set of the > mistakes detected by the **Checking Program**. 1. There is a **Checking Program** named `assignment11check` in the [Source Directory] on the CLS. You can execute this program by typing its (long) pathname into the shell as a command name: $ ~idallen/cst8207/15w/assignment11/assignment11check You learn one way to make this shorter in the current assignment. 2. Execute the above **Checking Program** as a command line on the CLS. This program will check your work, assign you a mark, and display the output on your screen. You may run the **Checking Program** as many times as you wish, allowing you to correct mistakes and get the best mark. **Some task sections require you to finish the whole section before running the Checking Program at the end; you may not always be able to run the Checking Program successfully after every single task step.** 3. When you are done with this assignment, and you like the mark displayed on your screen by the **Checking Program**, you must **redirect** only the standard output of the **Checking Program** into the text file `assignment11.txt` in your [Base Directory] on the CLS, like this: $ ~idallen/cst8207/15w/assignment11/assignment11check >assignment11.txt $ cat assignment11.txt - Use output redirection with that *exact* `assignment11.txt` file name. - Use that *exact* name. Case (upper/lower case letters) matters. - Be absolutely accurate, as if your marks depended on it. - Do not edit the output file. - Make sure the file actually contains the output of the **Checking Program**! - The file should contain, near the bottom, a line starting with: `YOUR MARK for` - Really! **MAKE SURE THE FILE HAS YOUR MARKS IN IT!** 4. Transfer the above single file `assignment11.txt` (containing the output from the **Checking Program**) from the CLS to your local computer. - You may want to refer to the [File Transfer] page for how to transfer the file. - Verify that the file still contains all the output from the **Checking Program**. - Do not edit this file! No empty files, please! Edited or damaged files will not be marked. Submit the file exactly as given. - The file should contain, near the bottom, a line starting with: `YOUR MARK for` - Really! **MAKE SURE THE FILE YOU UPLOAD HAS YOUR MARKS IN IT!** 5. Upload the `assignment11.txt` file from your local computer to the correct Assignment area on Blackboard (with the exact name) before the due date: 1. On your local computer use a web browser to log in to Blackboard and go to the Blackboard page for this course. 2. Go to the Blackboard *Assignments* area for the course, in the left side-bar menu, and find the current assignment. 3. Under *Assignments*, click on the underlined **assignment11** link for this assignment. a) If this is your first upload, the *Upload Assignment* page will open directly; skip the next sentence. b) If you have already uploaded previously, the *Review Submission History* page will be open and you must use the *Start New* button at the bottom of the page to get to the *Upload Assignment* page. 4. On the *Upload Assignment* page, scroll down and beside *Attach File* use *Browse My Computer* to find and attach your assignment file from your local computer. Make sure the assignment file has the correct name on your local computer before you attach it. 5. After you have attached the file on the *Upload Assignment* page, scroll down to the bottom of the page and use the *Submit* button to actually upload your attached assignment file to Blackboard. Use only *Attach File* on the *Upload Assignment* page. Do not enter any text into the *Text Submission* or *Comments* boxes on Blackboard; I do not read them. Use only the *Attach File* section followed by the *Submit* button. If you need to comment on any assignment submission, send me [EMail]. You can revise and upload the file more than once using the *Start New* button on the *Review Submission History* page to open a new *Upload Assignment* page. I only look at the most recent submission. You must upload the file with the correct name from your local computer; you cannot correct the name as you upload it to Blackboard. 6. **Verify that Blackboard has received your submission**: After using the *Submit* button, you will see a page titled *Review Submission History* that will show all your uploaded submissions for this assignment. Each of your submissions is called an *Attempt* on this page. A drop-down list of all your attempts is available. a) Verify that your latest *Attempt* has the correct 16-character, lower-case file name under the *SUBMISSION* heading. b) The one file name must be the *only* thing under the *SUBMISSION* heading. Only the one file name is allowed. c) No *COMMENTS* heading should be visible on the page. Do not enter any comments when you upload an assignment. d) **Save a screen capture** of the *Review Submission History* page on your local computer, showing the single uploaded file name listed under *SUBMISSION*. If you want to claim that you uploaded the file and Blackboard lost it, you will need this screen capture to prove that you actually uploaded the file. (To date, Blackboard has never lost an uploaded file.) You will also see the *Review Submission History* page any time you already have an assignment attempt uploaded and you click on the underlined **assignment11** link. You can use the *Start New* button on this page to re-upload your assignment as many times as you like. You cannot delete an assignment attempt, but you can always upload a new version. I only mark the latest version. 7. Your instructor may also mark files in your directory in your CLS account after the due date. Leave everything there on the CLS. **Do not delete any assignment work from the CLS until after the term is over!** - I do not accept any assignment submissions by EMail. Use only the Blackboard *Attach File*. No word processor documents. Plain Text only. - Use the *exact* file name given above. Upload only one single file of Linux-format plain text, not HTML, not RTF, not MSWord. No fonts, no word-processing. Linux plain text only. - **NO EMAIL, WORD PROCESSOR, PDF, RTF, or HTML DOCUMENTS ACCEPTED.** - No marks are awarded for submitting under the wrong assignment number or for using the wrong file name. Use the exact 16-character, lower-case name given above. - **WARNING:** Some inattentive students don’t read all these words. Don’t make that mistake! Be exact. **READ ALL THE WORDS. OH PLEASE, PLEASE, PLEASE READ ALL THE WORDS!** Appendix I: The Crontab Time ============================ This section shows you how to calculate your personal Crontab Time for use in your cron and at jobs. You need to know your nine-digit student number and how to calculate the arithmetic [modulus] of a number. > 1. Take your 9-digit student number and remove the first three digits > (probably `040`), leaving six digits. Use these last six digits as > follows: > 2. Take the first two of those six digits as a number, [modulo][modulus] > 12, and then add 1, giving a number between 1 and 12. This is your > month number. > 3. Take the next (middle) two of those six digits as a number, > [modulo][modulus] 24, giving a number between 0 and 23. This is your > hour number. > 4. Take the last two of those six digits as a number, [modulo][modulus] > 60, giving a number between 0 and 59. This is your minute number. > 5. Take the same last two of those six digits as a number, > [modulo][modulus] 28, and then add 1, giving a number between 1 and 28. > This is your day-of-the-month number. For example, if your nine-digit student number were `123456789`: 1. Remove the first three digits `123`, leaving the last six digits `45 67 89` 2. Using the first two digits `45`, the month would be `(45 mod 12) + 1 = 10` (October) 3. Using the next two digits `67`, the hour would be `67 mod 24 = 19` (7pm) 4. Using the last two digits `89`, the minute would be `89 mod 60 = 29` 5. Using the last two digits `89`, the day of the month would be `(89 mod 28) + 1 = 6` The Crontab Time for student number `123456789` is October 6 at 19h29 (7:29pm). **Exercise:** Show that The Crontab Time for student number `987654321` is 1. last six digits = `65 43 21` 2. month = `6` (June) 3. hour = `19` (7pm) 4. minute = `21` 5. day of month = `22` which is June 22 at 19h21 (7:21pm). -- | 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 [www.idallen.com]: http://www.idallen.com/ [hyperlink URLs]: indexcgi.cgi#Important_Notes__alphabetical_order_ [Assignments]: indexcgi.cgi#Assignments [Worksheets]: indexcgi.cgi#Worksheets__not_for_hand_in_ [Checking Program]: #checking-marking-and-submitting-your-work [Course Linux Server]: 070_course_linux_server.html [Package Management]: 520_package_management.html [Processes and Jobs]: 600_processes_and_jobs.html [System Log Files]: 580_system_log_files.html [Crontab and At Job Schedulers]: 630_crontab_at_job_scheduler.html [Sending EMail]: 070_course_linux_server.html#sending-email-from-the-cls [Reading EMail]: 630_crontab_at_job_scheduler.html#reading-email-from-cron-and-at-jobs [List of Commands You Should Know]: 900_unix_command_list.html [Remote Login]: 110_remote_login.html [Base Directory]: #set-up-the-base-directory-on-the-cls [Disk Usage]: 457_disk_usage.html [Job Control and Background Processes]: 600_processes_and_jobs.html#unixlinux-shell-job-control-and-background-processes [Search Path]: 400_search_path.html [Symbolic Link]: 460_symbolic_links.html [Quoting]: 440_quotes.html [Permissions]: 500_permissions.html [Line End Differences]: 015_file_transfer.html#text-file-line-end-differences [Notes on checking your work]: #notes-on-checking-your-work [The Crontab Time]: #appendix-i-the-crontab-time [Source Directory]: #the-source-directory [File Transfer]: 015_file_transfer.html [EMail]: mailto:idallen@idallen.ca [modulus]: https://en.wikipedia.org/wiki/Modulo_operation [Plain Text]: assignment11.txt [Pandoc Markdown]: http://johnmacfarlane.net/pandoc/