% CST8177 Assignment 01 - Review GNU/Linux Operating Systems I % Todd Kelley Richard Donnelly Ian! D. Allen - idallen@idallen.ca - www.idallen.com % Winter 2013 - January to April 2013 - Updated 2013-01-25 09:17 EST - [Course Home Page] - [Course Outline] - [All Weeks] - [Plain Text] Due Date and Deliverables ========================= - **Due Date**: `23h59 (11:59pm) Friday January 25, 2013 (end of Week 3)` - You have three weeks to do this review assignment, but your next assignment will be available in one week and will overlap this assignment. Don't delay! - Late assignments or wrong file names may not be marked. Be accurate. - **Available online**: Monday January 7, 2012 - **Prerequisites**: - [CST8207 GNU/Linux Operating Systems I] - an ability to **READ ALL THE WORDS** to work effectively - **Deliverables**: 1. One text file uploaded to Blackboard according to the steps in the [Checking Program] section below. 2. Directory structure 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!** Purpose of this Assignment ========================== 1. Get started on the [Course Linux Server] (**CLS**) 2. Review basic Linux command line operations and utilities, e.g. from [CST8207 GNU/Linux Operating Systems I]. Remember to **READ ALL THE WORDS** to work effectively and not waste time. Introduction and Overview ========================= This is an overview of what you will do in this assignment. Read all the words before you start working. Complete the [Tasks] listed below on the [Course Linux Server] (**CLS**). Run a [Checking Program] to verify your work as you go. Submit your marks. You will create file system structure in your home directory, with various directories, files, and links. You can use the [Checking Program] to check your work as you do the tasks. You can check your work with the checking program as often as you like before you submit your final mark. (Some tasks sections below require you to finish the whole section before running the checking program; you may not always be able to run the checking program successfully after every single task step.) When you are finished the tasks, leave these files, directories, and links in place as part of your deliverables. **Do not delete any assignment work until after the term is over!** Assignments may be re-marked at any time; you must have your term work available right until term end. This is a review lab, and all of the tasks can be completed with knowledge of the material from the prerequisite course [CST8207 GNU/Linux Operating Systems I]; however, you will probably need to refresh your memory of various topics by referring to the CST8207 course notes and the Linux man pages. Your lab instructor is there to help you, but he will want you to have tried consulting the notes and man pages first. The prevous term's course notes are available on the Internet here: [CST8207 GNU/Linux Operating Systems I]. All the notes files are also on the CLS. You can learn about how to read and search these 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]. Remember to **READ ALL THE WORDS** to work effectively and not waste time. Tasks ===== Do the following tasks in order, from top to bottom. **READ ALL THE WORDS!** and do not skip steps. The Source Directory -------------------- All references to the "Source Directory" below are to the directory `~idallen/cst8177/13w/assignment01/` and that name starts with a *tilde* character followed by a userid with no intervening slash. Set Up Tasks ------------ 1. Log in remotely to the [Course Linux Server] (**CLS**) from any existing computer. Pay particular attention to the special **non-Algonquin password** you must use, or else you will lock yourself out of the machine. If the public DNS name doesn't work on campus (time out), try the Algonquin private name instead. **All work in this assignment must be done on the CLS.** 2. Ensure you have set the seven BASH shell options and five BASH aliases in your `$HOME/.bashrc` as recommended in [CST8207 Startup Files]. If these options and aliases are not set when you log in, edit the `.bashrc` file to add them and then log out and log back in. If they still aren't set, also fix your `$HOME/.bash_profile` file to *source* your `.bashrc` file, as shown. We recommend adding the following two additional shell options: - `shopt -s cmdhist` - `shopt -s histappend` 3. In your home directory, create a directory called: `Assignments`\ (As with all Unix/Linux pathnames, be precise in the spelling and capitalization.) In this document, `Assignments/` refers to this directory that contains all your course Assignments. 4. Under `Assignments/`, create a directory named: `assignment01` (As with all Unix/Linux pathnames, be precise in the spelling and capitalization.) All output files in the assignment must go under this `assignment01/` directory. Put output files here. 5. There is a [Checking Program] named `assignment01check` in the [Source Directory] on the CLS. Create a symbolic link to this program named `check` under your new `assignment01` directory so that you can easily run the program to check your work and assign your work a mark. Note: You can create a symbolic link to this executable program but you do not have permission to read or copy the program file. To verify the symbolic link, try executing it (just as you did last term). Check your work so far using the `assignment01check` program symlink. Simple Tasks ------------ 1. From your home directory, use the `ls` command with options to give a long listing (showing permissions), include all hidden files, include inode numbers, and recursively include all subdirectories. (Do not use any other options.) When the output is correct, redirect the output of this command into new file `listing_start` under `assignment01` - it will be at least 16 lines of output. *(If you have files from CST8207 in your account, you may get some "permission denied" errors doing the listing \[ignore the errors\] and the number will be many more than 16 lines.)* 2. Run the `whoami` command. When the output is correct, redirect the output of this command into new file `whoami` under `assignment01` 3. Run the `id` command. When the output is correct, *append* the output of this command to existing file `whoami` under `assignment01`. (Note the word *append*). The file must now have *two* lines of output in it. Check it! 4. Rename the file `whoami` to have the new name `whoamiid` (in the same directory) and make extra sure you spelled the new name correctly. 5. Use a command to count *only* the number of lines (not characters or words) in file `read.txt` in the [Source Directory]. (You'll know you have the right file if the size is 818 characters.) When the output is correct, redirect the output of this command (the output containing *only* the *line* count number, not any other numbers) into new file `readlines` under `assignment01` 6. Use a command to search for and display the single line containing the exact text phrase "*permissions is useless*" located inside any one of the text files (files having a `.txt` file extension) located in the `notes/` directory of the previous term CST8207 (fall 2012). The [Introduction and Overview] explains where to find these notes and how to search them, just as you did last term. When the output is correct, redirect the *one line of output* of this command into new file `useless` under `assignment01` The file should be *one* line long. Check your work so far using the `assignment01check` program symlink. File Permission Tasks --------------------- 1. Copy the binary program file `/bin/hostname` three times to files named `read_only`, `write_only`, and `execute_only` under your `assignment01` directory. This is a BINARY program file, so do not display the content of the file on your terminal screen! 2. Change the permissions on all three copied files so that *group* and *other* have no permissions. (You can do this with one command name and a file GLOB pattern.) 3. Change the permissions on the `read_only` file so that only you can read the file but not write or execute the file. a) Verify readability of the file by using any command that reads the content of the file. For example, you can word count the file or try to copy the file to `/dev/null`. b) Verify non-writability by attempting to re-copy `/bin/hostname` to the file. (It should fail with "permission denied".) c) Verify non-executability by attempting to execute the file as a program. (It should fail with "permission denied".) You may need to review how to execute a file using a pathname. The error must be "permission denied" not "no such file" or "command not found". 4. Change the permissions on the `write_only` file so that only you can write (including append to) the file but not read or execute the file. a) Using operations similar to the previous file, verify that you can write the file but not read or execute it. 5. Change the permissions on the `execute_only` file so that only you can execute the file but not read or write the file. a) Using operations similar to the previous files, verify that you can execute the file but not read or write it. Check your work so far using the `assignment01check` program symlink. Directory Permission Tasks -------------------------- 1. Make the following directory structure under `assignment01/` permissions/ permissions/read_only/ permissions/write_only/ permissions/execute_only/ 2. Change the permissions on the `permissions/` directory so the owner (you) can read, write, and search, but *group* and *other* have no permissions. 3. Change the permissions on all three subdirectories of `permissions/` so that that *group* and *other* have no permissions. (You can do this with one command name and a file GLOB pattern.) 4. Change the permissions on `read_only/` so that you can see the names in the directory (with `echo read_only/*` or similar), but cannot take an accurate long listing, and cannot create files, and cannot `cd` into the directory. (Verify that you can/cannot do these things!) 5. Change the permissions on `write_only/` so that you cannot see the names in the directory, but you can add new files to the directory, delete files from the directory, and `cd` into the directory. (Verify that you can/cannot do these things!) 6. Change the permissions on `execute_only/` so that you can (only) `cd` into the directory. You cannot see the names in the directory or add or delete files from the directory. Verify! Check your work so far using the `assignment01check` program symlink. `find` Command Tasks -------------------- This section refers to the maze of partially hidden files and directories under directory `~idallen/cst8177/13w/assignment01/maze` 1. Find in the maze a single hidden file with a name similar to `.abcd0001*txt`, but look for the name that starts with a period followed by your own Blackboard userid, not the fake userid `abcd0001`. To look for the file, replace the string `abcd0001` in `.abcd0001*txt` with your own userid before you look. The name you find must be exactly 13 characters long and contain a period and a real asterisk. It must have no leading or trailing blanks around it. Hint: You might want to use a command that finds files by *basename* to do this. (Do not try to use "cd" and "ls" to find your file; the maze is really big.) 2. When you find the right file name (there is only one for your userid), put its shortest *full absolute pathname* into new file `foundmaze` under your `assignment01` directory. Note: Shortest absolute pathnames contain no `/./` or `/../` or tilde ("`~`") expressions; simplify the path to the shortest possible absolute pathname. Check your work so far using the `assignment01check` program symlink. Symbolic Link Tasks ------------------- 1. Create an absolute soft (symbolic) link to the Linux password file; create the symlink under your `assignment01` directory and name the symlink `mypasswd` and verify you can read the text in the password file through the `mypasswd` symbolic link. (The text of the new `mypasswd` symlink should be an absolute pathname to the password file.) Display file attributes and inode numbers of both the password file and the `mypasswd` symbolic link, and confirm that they are different. 2. Make a new relative soft link to the `mypasswd` symlink you just created, named `alsopasswd`, also in the `assignment01` directory. (The text of the new `alsopasswd` symlink should be the shortest relative pathname to `mypasswd` in the same directory.) Now, `alsopasswd` links to `mypasswd` that links to the password file. Make sure you can also read the password file using the new `alsopasswd` symlink. **Hint:** All of "`././foo`" and "`./foo`" and "`foo`" are relative pathnames that lead to the same place. Which one is *shortest*? 3. Rename the `mypasswd` symlink to be `otherpasswd`. Now, `alsopasswd` is a (broken) symlink to a non-existent `mypasswd` symlink. Confirm that you can no longer use `alsopasswd` to read the text of the password file. Check your work so far using the `assignment01check` program symlink. Hard Link Tasks --------------- > Note 2012-01-07: This section has been rewritten not to use the password > file, because of inode changes when the file is updated. -IAN! 1. Create a hard link to the `read.txt` file in the [Source Directory] (you counted the lines in this file earlier); name the hard link `hardread` in the `assignment01` directory. (Note; On some versions of Unix/Linux, you are not allowed to hard link to a file you cannot write. That protection has been disabled on the CLS.) Verify that you can read the file using the `hardread` hard link. Display file attributes and inode numbers of both the `read.txt` file and the `hardread` hard link, and confirm that they are identical. (Only the pathnames will be different.) These hard links are just two names for the same file inode. 2. Make a new hard link to `hardread` named `newhard` in the same `assignment01` directory. Display file attributes and inode numbers of the `read.txt` file and both the new hard link files, and confirm that all three are identical. (Only the pathnames will be different.) These hard links are just three names for the same file inode. 3. Rename `hardread` to `junkread` and note that this does *not* break the hard link for `newhard`. Verify that all three files have the same attributes and inode numbers and that you can read the text of the `read.txt` file through both hard links, as before. Check your work so far using the `assignment01check` program symlink. Finishing Tasks --------------- 1. Make a backup copy of your `listing_start` file, in case you accidentally overwrite it in the next step. 2. From the same starting directory, repeat the command you used to create `listing_start` at the beginning of this lab, but redirect the output this time into the file `listing_end` in the same directory as `listing_start`, and make sure that all errors (standard error output) also go into the output file and not on the screen. (You might find your shell *history* useful here. There is a special syntax to also redirect error messages.) 3. Use the `diff` command to compare the earlier listing file to the previous one you did before starting this lab. Note the many changes! Check your work a final time using the `assignment01check` program symlink. Submit your final mark following the directions below. 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 marks file to Blackboard. 1. There is a [Checking Program] named `assignment01check` in the [Source Directory] on the CLS. Create a symbolic link to this program named `check` under your new `assignment01` directory so that you can easily run the program to check your work and assign your work a mark. Note: You can create a symbolic link to this executable program but you do not have permission to read or copy the program file. To verify the symbolic link, try executing it. 2. Execute the above "check" program using its symbolic link. (Review the [CST8207 Search Path] notes if you forget how to run a program by pathname from the command line.) This program will check your work, assign you a mark, and display the output on your screen. (You may want to paginate the long output so you can read all of it.) You may run the "check" program as many times as you wish, to correct mistakes and get the best mark. 3. When you are done with checking this assignment, and you like what you see on your screen, redirect the output of the [Checking Program] into the text file `assignment01.txt` under your `assignment01` directory. Use the *exact* name `assignment01.txt` in your `assignment01` directory. You only get *one* chance to get the name correct. Case (upper/lower case letters) matters. Be absolutely accurate, as if your marks depended on it. Do not edit the file. 4. Transfer the above `assignment01.txt` file from the CLS to your local computer and verify its contents. Do not edit this file! No empty files, please! Edited or damaged files will not be marked. You may want to refer to this updated page on [File Transfer]. 5. Submit the `assignment01.txt` file under the correct Assignment area on Blackboard (with the exact name) before the due date. Upload the file via the **assignment01** "Upload Assignment" facility in Blackboard: click on the underlined **assignment01** link in Blackboard. Use "**Attach File**" and "**Submit**" to upload your plain text file. No word-processor documents. Do not send email. Use only "Attach File". Do not enter any text into the **Submission** or **Comments** boxes on Blackboard; I do not read them. Use only the "**Attach File**" section followed by the **Submit** button. (If you want to send me comments about your assignment, use email.) 6. Your instructor may also mark the `assignment01` 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!** Use the *exact* file name given above. Upload only one single file of plain text, not HTML, not MSWord. No fonts, no word-processing. Plain text only. Did I mention that the format is plain text (suitable for VIM/Nano/Pico/Gedit or Notepad)? **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 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!** -- | Todd Kelly / Richard Donnelly and | 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 [Course Home Page]: .. [Course Outline]: course_outline.pdf [All Weeks]: indexcgi.cgi [Plain Text]: assignment01.txt [CST8207 GNU/Linux Operating Systems I]: ../../../cst8207/12f [Checking Program]: #checking-marking-and-submitting-your-work [Course Linux Server]: 000_course_linux_server.html [Tasks]: #tasks [CST8207 Startup Files]: ../../../cst8207/12f/notes/210_startup_files.html [Source Directory]: #the-source-directory [Introduction and Overview]: #introduction-and-overview [CST8207 Search Path]: ../../../cst8207/12f/notes/400_search_path.html [File Transfer]: 220_file_transfer.html [Pandoc Markdown]: http://johnmacfarlane.net/pandoc/