% CST8177 Assignment 01 - Review GNU/Linux Operating Systems I % Todd Kelley, Ian! D. Allen – – [www.idallen.com] % Winter 2014 - January to April 2014 - Updated Thu Mar 20 20:17:44 EDT 2014 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**: `23h59 (11:59pm) Friday January 24, 2014 (end of Week 3)` - You have two 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. Please be punctual. - **Available online** - Version 1 – 08h30 Wednesday January 8, 2014 - **Prerequisites** - [CST8207 GNU/Linux Operating Systems I] - All Class Notes since the beginning of term. - 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 ========================== > **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. 1. Review [Remote Login] to the [Course Linux Server] (**CLS**) 2. Review basic Linux command line operations and utilities, e.g. from [CST8207 GNU/Linux Operating Systems I]. Introduction and Overview ========================= This is an overview of how you are expected to complete this assignment. Read all the words before you start working. 1. Complete the **Tasks** listed below. 2. Verify your own work before running the [Checking Program]. 3. Run the [Checking Program] to help you find errors. 4. Submit the output of the [Checking Program] to Blackboard before the due date. 5. **READ ALL THE WORDS** to work effectively and not waste time. 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 s/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]. > 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/cst8177/14w/assignment01/` and that name starts with a *tilde* character `~` followed by a userid 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). 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. - Your instructor will 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 ------ 1. Do a [Remote Login] to the [Course Linux Server] (**CLS**) from any existing computer, using the name appropriate for whether you are on-campus or off-campus. Pay particular attention to the special **non-Algonquin password** you must use, or else you will lock yourself out of the machine. **All work in this assignment must be done on the CLS.** 2. Create the following directory structure in your CLS HOME directory and record (for study purposes) the series of Unix commands you used to create it. Spelling and capitalization must be exactly as shown: CST8177-14W `-- Assignments `-- assignment01 **This directory is the base directory for most pathnames in this assignment. Store your files and answers here.** 3. There is a [Checking Program] named `assignment01check` in the [Source Directory] on the CLS. Follow the instructions in the first two steps at the start of [Checking Program] to create a working symbolic link to this program. 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 2013). 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 overwrite the file. Attempts to overwrite 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!) **Hint:** Of course `echo read_only/*` will only show file names if you actually create those files. 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. Finding files in a maze ----------------------- 1. Under the [Source Directory] there is a directory named `maze` (four letters). This maze contains many hidden sub-directories. Use a single command (no pipes needed) to find in the maze a single hidden file with a *basename* similar to `.abcd0001*txt`, but look for the basename 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 basename 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#1:** 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.) **Hint#2:** If you want to find a name containing a real asterisk, you may need to *escape* the asterisk to stop it from being used as a pattern character (wildcard), and you need to do this both for the shell that reads your command line and for the command that finds the files. if you get the escaping right, you will find exactly one file. 2. When you find the right file basename (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 the *shortest*? Always use the *shortest* relative pathname. 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 --------------- 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! When you are done ----------------- That is all the tasks you need to do. Check your work a final time using the [Checking Program] and save the output as described below. Submit your 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. 2. Execute the above “check” program using its new symbolic link. (Review the [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. **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 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. Case (upper/lower case letters) matters. Be absolutely accurate, as if your marks depended on it. Do not edit the file. Make sure the file actually contains the output of the checking program! 4. Transfer the above `assignment01.txt` file from the CLS to your local computer and 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. You may want to refer to your [File Transfer] notes. 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 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 [www.idallen.com]: http://www.idallen.com/ [hyperlink URLs]: indexcgi.cgi#XImportant_Notes__alphabetical_order_ [CST8207 GNU/Linux Operating Systems I]: ../../../cst8207/13f [Checking Program]: #checking-marking-and-submitting-your-work [Course Linux Server]: ../../../cst8207/13f/notes/070_course_linux_server.html [Remote Login]: ../../../cst8207/13f/notes/110_remote_login.html [Source Directory]: #the-source-directory [Introduction and Overview]: #introduction-and-overview [Symbolic Link]: ../../../cst8207/13f/notes/460_symbolic_links.html [Search Path]: ../../../cst8207/13f/notes/400_search_path.html [File Transfer]: ../../../cst8207/13f/notes/015_file_transfer.html [Plain Text]: assignment01.txt [Pandoc Markdown]: http://johnmacfarlane.net/pandoc/