% CST8207 Assignment 05 -- GLOB wildcard patterns, finding files using GLOB, redirection and pipes % Ian! D. Allen -- -- [www.idallen.com] % Winter 2017 - January to April 2017 - Updated 2017-09-25 04:21 EDT - [Course Home Page] - [Course Outline] - [All Weeks] - [Plain Text] 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) Monday February 27, 2017 (start of Week 7)` - You have more than a week to do this assignment because you need get together with friends in a study group and **do two worksheets first**. Do the worksheets first and check your answers with your classmates. - Your next assignment will overlap this assignment. Start work on this now! Don't delay! - Late assignments or wrong file names may not be marked. Please be accurate and punctual. - **Available online** - Version 1 -- 03:30 February 10, 2017 - **Prerequisites** - All [Class Notes][hyperlink URLs] since the beginning of term. - All your previous [Assignments]. - All the work in [Worksheet #04 PDF] and [Worksheet #05 PDF]. - 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. Use [Remote Login] to connect to the [Course Linux Server] (**CLS**) and use commands in [The Unix/Linux Shell] to create directory structure and files for marking on the **CLS**.\ **Do not delete any assignment work from the CLS until after the term is over!** **WARNING:** Some inattentive students upload Assignment #5 into the Assignment #4 upload area. Don't make that mistake! Be exact. Purpose and Background ====================== This assignment is based on your weekly [Class Notes][All Weeks] and covers these topics: - Select names using GLOB patterns. - Search the course notes for keywords using GLOB patterns. - Copy 100 files based on a complex GLOB pattern. - Identify Unix, Windows, and Macintosh text file types. - Find file names in a directory using a GLOB pattern. - Find basenames recursively in a maze using a GLOB pattern. - Use redirection to append to a file. - Search some system log files and produce summary information Prerequisites: Do Worksheet 4 and Worksheet 5 --------------------------------------------- You must complete the two Worksheets before attempting this assignment. The worksheets depend on the Readings in the weekly course notes, especially [Shell GLOB Patterns] and [Redirection and Pipes]. These worksheets prepare you to do the rest of the tasks listed below. Failure to complete the worksheets will make the rest of this assignment very difficult. Do the worksheets first! Record and save all your worksheet answers for study and quizzes! 1. Use LibreOffice or OpenOffice to complete [Worksheet #04 ODT]. (View online: [Worksheet #04 HTML].) 2. Use LibreOffice or OpenOffice to complete [Worksheet #05 ODT]. (View online: [Worksheet #05 HTML].) See your previous assignments for how best to fill in the worksheets. The worksheets will not be marked, but your professor may ask to see them. How to complete this Assignment =============================== For full marks, follow these directions exactly: 1. These tasks must be done in your account via [Remote Login] to the [Course Linux Server]. 2. Do the tasks in order, from top to bottom. Do not skip steps. Most tasks are independent, but some depend on successful completion of a previous task. 3. **READ ALL THE WORDS** in each task before you begin the task, especially all the **Hints** and links. 4. Verify your own work before running the **Checking Program**. You won't have a checking program at your job interview and the **Checking Program** is not guaranteed to check everything. 5. Run the **Checking Program** at the end of the task to grade your work and help you find some of your errors. A perfect mark from the **Checking Program** does *not* mean your answers are correct. 6. When you are done with this Assignment, submit the output of the **Checking Program** to Blackboard before the due date, following the directions given at the end of this Assignment. Notes on doing assignment work ------------------------------ 1. 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. The assignment tells you where you can safely check your work. 2. 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 for your instructor to verify. 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!** 3. You can modify your work and check it with the **Checking Program** as often as you like before you submit your final mark to Blackboard. You can upload your marks to Blackboard as many times as you like before the due date. Partial marks are accepted. 4. 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 after you have submitted your final mark to Blackboard. 5. 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 future assignments very difficult. 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]. Draw File System Diagrams ------------------------- Many students find it extremely helpful to draw a quick graph/picture of their file system directory structure on paper before attempting to answer questions about relative pathnames. You need to be able to visualize the relative locations of names in the file system tree to answer these questions. Draw the trees on paper! The Source Directory -------------------- All references to the **Source Directory** below are to the CLS directory `~idallen/cst8207/17w/assignment05/` 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. Tasks ===== Have you completed all the prerequisites, before attempting these tasks? Log in to the Course Linux Server --------------------------------- 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. **All work in this assignment must be done on the CLS.** Set your `PS1` Shell Prompt --------------------------- 1. Set your `PS1` shell prompt, as you did in a previous assignment. Set Up -- The Base Directory on the CLS --------------------------------------- 1. Create the `assignment05` directory in your usual `Assignments` directory. **Hints:** See your previous assignment for hints on doing the above. **This `assignment05` 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.** Run the [Checking Program] to verify your work so far. Using shell GLOB patterns to select names ----------------------------------------- You need to understand [Shell GLOB Patterns] to do this task. 1. Make your HOME directory your current directory. ### `oldnotes` `newnotes` 2. In your HOME directory, create two symbolic links to the old and new course notes for CST8207 using the `ln -s` command and option and the method described in [Copies of the CST8207 Course Notes]. (The old notes must be term `16f` and the new notes must be term `17w` in the pathnames you use.) 3. Do a long listing of the new `oldnotes` symlink and verify that it looks similar to this (but the userid and time will differ): lrwxrwxrwx 1 abcd0001 abcd0001 52 Feb 10 00:00 oldnotes -> /home/idallen/public_html/teaching/cst8207/16f/notes You should be able to do `ls oldnotes | less` and see all the course notes file names from last term (`16f`). If not, remove and redo the symlink. 4. In your HOME directory, use the `ls` command with no options and a single shell GLOB pattern to match all pathnames under the symbolic link `oldnotes/` that end in `.txt` and display all the names on your screen. The shell will find 87 pathnames ending in `.txt`, and the `ls` command will display those 87 names on your screen. One of the last names on your screen should look exactly like this: oldnotes/worksheet08.txt Make sure you see 87 pathnames. (You can use a command pipeline to count the lines and words to be sure you have 87.) **Hints:** No pipeline or `find` commmand is required to generate the 87 pathnames, just use the `ls` command with no options and one single GLOB pattern argument starting with the symlink `oldnotes/`. This use of a GLOB pattern on a command line is illustrated in [Copies of the CST8207 Course Notes]. The example in the notes uses the given GLOB pattern to generate pathnames to the `ls` command and count them. Follow the example and display the 87 pathnames on your screen instead of counting them. (Don't use any redirection.) ### `oldfound.txt` 5. When the `ls` output on your screen is correct (87 names), redirect the output 87 names into file `oldfound.txt` under your [Base Directory] (not under your current HOME directory). The file must contain 87 names, one per line. **Note:** The `ls` command will put each name on a separate line when output is not being sent to your screen. 6. Still in your HOME directory, use the `echo` command with a shell GLOB pattern to match all pathnames under `oldnotes/` that contain the acronym `RTFM` *anywhere* in the file name and display the names on your screen. The shell will find two pathnames, one ending in `.html` and the other in `.txt`, and the `echo` command will display those two names on your screen on one line. **Hints:** See the previous Hint. Use only a GLOB pattern. ### `foundman.txt` 7. When the `echo` output on your screen is correct (two names on one line), redirect the output into file `foundman.txt` under your [Base Directory] (not under your current HOME directory). The file must contain two names on one line. 8. Again in your HOME directory, use the `echo` command with a shell GLOB pattern to match pathnames under `oldnotes/` that contain the digit `2` anywhere in the file name and end in the extension `.pdf` at the end. The shell will find four pathnames, each ending in `.pdf` at the end, and the `echo` command will display those four names on your screen on one (long) line. 9. When the `echo` output on your screen is correct (four names on one long line), change the command name from `echo` to `ls` and add an option to show the full, long information about the pathnames. You should see four lines on your screen, showing the full file information for each of the four files. One of the lines should look similar to this: -rw-r--r-- 1 idallen idallen 27865 Aug 29 23:57 oldnotes/2016-2017_CST8207.pdf ### `foundpdf.txt` 10. Now redirect the four lines of long output on your screen into file `foundpdf.txt` under your [Base Directory] (not under your current HOME directory). The file must contain four lines and approximately 36 words. Run the [Checking Program] to verify your work so far. Searching for text inside files (e.g. course notes) --------------------------------------------------- You need to understand [Shell GLOB Patterns] to do this task. As mentioned in [Worksheet #03 HTML], you can choose which text search command you use depending on whether special characters are being used in the search string. You should always use the fixed-string `fgrep` command to begin with in this introductory course. You will learn regular expressions and the `grep` command next term in Linux II. Use `fgrep` for this assignment. Always verify that the correct output appears on your screen *before* you redirect the output into a file. [**You can only redirect what you can see.**] Make your [Base Directory] your current directory for this section. ### `myaccount.txt` 1. Search for lines containing your login userid in the password file. You should find exactly one line. *(For an explanation of what the seven fields are in this line, see `man 5 passwd`.)* 2. When the output is correct (one line) then redirect the output into file `myaccount.txt` in your [Base Directory]. The file should contain one line. 3. Search for lines containing a period (dot) character (`.`) in the file `special.txt` in the [Source Directory]. **Hint:** A period can be a special character. Choose the right text searching command, as described at the start of this section. The word count of the six lines of correct output should be: `6 56 320` ### `dotlines.txt` 4. When you have the correct six lines of output on your screen, redirect that six lines of output (not the word count) into file `dotlines.txt` under your [Base Directory]. The word count of the file should be the same as above (six lines). 5. Search for lines containing two adjacent asterisk characters (`**`) in the file `special.txt` in the [Source Directory]. **Hint:** An asterisk is a special character to the shell. Hide the asterisks so that the shell does not GLOB expand them. Also choose the right text searching command, as described at the start of this section. The word count of the four lines of correct output should be: `4 40 239` ### `starlines.txt` 6. When you have the correct four lines of output on your screen, redirect that four lines of output (not the word count) into file `starlines.txt` under your [Base Directory]. The word count of the file should be the same as above (four lines). ### Searching for keywords in the course notes If you can't remember which web pages discuss a topic, you can search for keywords in all the web pages at once from the command line. ### `oldnotes` `newnotes` 7. In your [Base Directory], create two more symbolic links to the old and new course notes for CST8207, as you did inside your HOME directory earlier in this assignment. Make the [Base Directory] your current directory. In [Copies of the CST8207 Course Notes], see the example use of `fgrep` with shell GLOB patterns to match `*.txt` files in these `oldnotes` and `newnotes` directories. The GLOB pattern easily generates a huge list of file names for `fgrep` to search inside. 8. In the old course notes from last year, use one command to search inside all the `.txt` files for the word `Filezilla` (spelled exactly as shown, case-sensitive). Only four lines of text should display, from four files. Each line of text should be preceded by the file name in which it was found. (The word count of the output must be `4 46 389`.) **Hint:** You will need to use the same GLOB pattern you used earlier in this assginment to match all the `.txt` files under `oldnotes`. This time, use the GLOB pattern to make the shell give all the file names to the command that searches for text inside all those files. No pipes are needed to find these lines; use just one command with no options and a single GLOB pattern. If you see more than four lines of output, you are likely using options that make the search case-insensitive. If your word count is wrong because the file names are missing, you are likely using unnecessary pipes. No pipes are needed to find the four lines. 9. Repeat the above search in all the `*.txt` files, but add the searching option that ignores case distinctions when matching lines in the files (RTFM). Now, 11 lines are found in six different files and the word count of the output should be `11 107 1042`. **Hint:** These text-searching commands are case-sensitive by default -- searching inside files for lines containing `abc` won't find any lines containing `ABC` unless you use an option to *ignore case distinctions* during the search. (What option? RTFM) ### `zillalines.txt` 10. Redirect the above 11 lines of output (not the word count) into a file named `zillalines.txt` under your [Base Directory]. The word count of this file should match the one above (11 lines). Run the [Checking Program] to verify your work so far. The cracker WAREZ 100 files --------------------------- - You need to understand [Shell GLOB Patterns] to do this task. - Read All The Words in this section before you start working. Especially, read all the **Hints** before you begin! The "story" here is that a malicious cracker has dumped a bunch of WAREZ files in a directory on the server and has hidden them among thousands of other files. (See .) Your job is to take a copy of the WAREZ files, and only the WAREZ files, for use in a court case. You must not touch or copy any other files, only the WAREZ files. 1. There is a directory named `warez` under the [Source Directory]. Hidden (really hidden) deeper under this directory is one single directory containing over **109,000** names. Use `cd` and the Hints below carefully to find this huge hidden directory and **make this huge directory your current directory**, so that you can experiment with the GLOB pattern you will need in the following questions. **Hints:** Be careful about typing `ls` in this huge directory without using any output pagination pipe -- the amount of output may flood your terminal window for some time and even a `^C` interrupt may take a minute or two to interrupt the command! One way to avoid flooding your screen is by using `ls | wc` to count how many pathnames would be output on your screen before you do just `ls`. Be careful! **Hints:** This isn't a maze. There is only *one* path down to the huge hidden directory inside the `warez` directory, though the way is *hidden*. Remember not to type `ls` in this large directory, when you find it, because the output is very large! Do not continue until you have found the directory containing the huge number of files. Make this huge directory your current directory. Exactly 100 files in this huge directory (your current directory) have names that contain your userid (which must be matched lower-case) followed somewhere later by the text string *warez*, where *warez* is **case-insensitive** and may appear in any combination of upper- and lower-case letters, e.g. `warez`,`Warez`,`wArez`,`waREz`, etc. Any amount of text may appear before your userid, between your userid and the *warez*, and after the *warez*. Some sample file names for userid *abcd0001* might look like these (note that the *warez* word *must* always follow the userid in all the required file names): - `PTKabcd0001PTKwAreZkmfGTDDeNTJFZ` - `zynabcd0001uKVUFOsCXaGFWZPECbYWVFKzynuKWaREZv` - `HhUtfgYtyGhjJADGekCAkgtZEKsTGKdYZZabcd0001ADGekCwaREZZaFSrXJnxGex` Many of the file names are up to 100 characters long. ### `warez` 2. From in the huge directory, use one single copy command and a single shell GLOB pattern to copy all 100 (exactly 100) of these cracker files (and no others) into a new directory named `warez` that you must first create in your own [Base Directory]. Make sure you preserve the modify times of the copied files, as you did in a previous lab. (In this simulation, all the files are empty.) **Hints:** Before you try to copy any files, use `echo` with the GLOB pattern into word count to [verify your GLOB patterns before using them]. The `echo` with GLOB pattern should produce exactly 100 pathnames. *The shell must correctly expand the GLOB pattern argument to `echo` before you try to use the same GLOB pattern in a copy command.* Once you can echo the 100 pathnames correctly, use exactly the same GLOB pattern to generate the source pathnames in a copy command. **Do not use a pipe or `find` or `fgrep` to select the file names.** Use only the copy command with a GLOB pattern for the source files, as you did in section 4.1 of [Worksheet #04 HTML]. The shell can do all the file name matching using the right GLOB pattern for the source files. **Do not quote the shell GLOB patten.** Quoting hides metacharacters and turns *off* shell GLOB patterns. You *want* the shell to expand the GLOB pattern for this task! (If you were passing a GLOB pattern as an expression in a `find` command, you would quote it so that the shell didn't expand it. That is not what you are doing here.) ### `warezcopy.sh` 3. Put the copy command line that you used into file `warezcopy.sh` in your [Base Directory]. Pay attention to the file name extension in this file name. **Hints:** Make sure that the content of the file is exactly the same as the copy command you typed, with no special characters expanded. The number of blank-separated words in the file should be about four. **Hints:** The best way to put this command line in the file is to use a Linux text editor, or you can use the `cat` keyboard and EOF method from section 5.5a in [Worksheet #05 HTML]. Read this Warning: > **Warning:** It is tricky to use `echo` with redirection to put this > command line into the file because the line contains shell metacharacters. > You can't just stick `echo` on the front of a command line that contains > shell metacharacters such as GLOB patterns; the shell will expand all those > metacharacters before the `echo` command runs. You will need special > [Quoting] to make it work. You will need to hide all the shell > metacharacters in the command line from the shell. Make sure the command > line echoes correctly to the screen before you try to redirect it into the > file. **You can only redirect what you can see!** Use a text editor > instead! 4. You can check your work by doing a listing of your `warez` directory and counting the number of names that were copied. All the files should have their original modify dates preserved -- verify this. Run the [Checking Program] to verify your work so far. Finding files in a directory using a shell GLOB pattern ------------------------------------------------------- You need to understand [Shell GLOB Patterns] to do this task. ### *abcd0001.txt* 1. Under the [Source Directory] there is a name `maze` (four letters). What is the absolute path of this `maze` under that directory? Put the absolute pathname of this `maze` in that directory into a file in your [Base Directory] with a *basename* similar to *abcd0001.txt*, but use the basename that starts with your *own* Blackboard userid, not the fake userid *abcd0001*. Use your own userid in the file name. Save the actual absolute pathname, not a shell tilde short-cut for an absolute pathname. (Do not start the name with a tilde.) The file *basename* must be exactly 12 characters long. The absolute pathname of the maze itself is over 40 characters long. You will need this maze absolute pathname in several places, below. 2. Use the `ls` command and a single shell GLOB pattern to display on your screen on separate lines the absolute paths of all names under the above `maze` directory that begin with your userid. **Hints:** Use the `ls` command (with no options) with a single absolute path shell GLOB pattern as an argument, in a manner similar to how you displayed all the `tty` names in section 4.1 of [Worksheet #04 HTML]. Use the actual absolute pathname, not a shell tilde short-cut for an absolute pathname. Do not start the name with a tilde. **Hints:** You should see six absolute pathnames. One of the six absolute pathnames will end in *abcd0001.txt* where *abcd0001* is your own userid. Each of the six absolute pathnames should contain seven forward slashes. The word count of the six output lines should be `6 6 349`. Do not use any options to `ls`. ### `FirstMaze.txt` 3. When you have the correct `ls` command that generates six lines of absolute pathname output, redirect and save the six lines into file `FirstMaze.txt` in your [Base Directory]. **Hints:** The word count of the file should also be `6 6 349`. ### `FirstMaze.sh` 4. Save the exact `ls` command line with GLOB pattern that you used in item 2 above into file `FirstMaze.sh` in your [Base Directory]. Pay attention to the file name extension in this file name. **Hints:** The file should contain only two blank-separated words: the command name and a single GLOB pattern. Do not save the redirection that you added in item 3 above. The word count of the file should show `1 2 57`. **Hints:** Make sure that the content of the file is exactly the same as the `ls` command you typed in item 2, with no special characters expanded. The number of blank-separated words in the file should be exactly two: the command name and a single GLOB pattern argument. Running the command by typing `sh -u FirstMaze.sh` should print the six pathnames on your screen. **Hints:** The best way to put this command line in the file is to use a Linux text editor, or you can use the `cat` keyboard and EOF method from section 5.5a in [Worksheet #05 HTML]. Read this Warning: > **Warning:** It is tricky to use `echo` with redirection to put this > command line into the file because the line contains shell metacharacters. > You can't just stick `echo` on the front of a command line that contains > shell metacharacters such as GLOB patterns; the shell will expand the GLOB > patterns before the `echo` command runs. You will need special [Quoting] to > make it work. You will need to hide all the shell metacharacters in the > command line from the shell. Make sure the command line echoes correctly to > the screen before you try to redirect it into the file. **You can only > redirect what you can see!** Use a text editor instead! Run the [Checking Program] to verify your work so far. These six pathnames are only six of the many file names in the maze that start with your userid. We need to find them all, in all the sub-directories, too. Finding files recursively in a directory using a `find` GLOB pattern -------------------------------------------------------------------- You need to understand [Shell GLOB Patterns] and [Finding Files] to do this task. Standard GLOB patterns when expanded by your shell can only match names in one directory; they don't recursively search all the directories in the entire maze. To find *all* the names in the maze that start with your userid, in all directories, we can't use the shell to expand the GLOB pattern. We need to hide the GLOB pattern from the shell and pass the GLOB pattern to a command that recursively searches a directory. (You have used this command many times already.) ### Quoting the GLOB Pattern You must hide the GLOB pattern from the shell and pass it unchanged to the command that recursively searches directories. GLOB pattern metacharacters work the same way to match *basenames*, as shown in the examples in [Finding Files]. Do not let the shell expand the GLOB pattern! We need to hide the GLOB patterns from the shell, since we want to pass the GLOB patterns unchanged to the command we use. Here's how: 1. Using the search tools in your web browser (not on the CLS), look for the string `quote` in the course notes web page on [Searching for and finding files by name, size, use, modify time, etc.][Finding Files] Read *all* the paragraphs containing this `quote` word (search multiple times) and remember the importance of quoting. You will need to know how to do this quoting when you start the finding and searching work for this task on the CLS, below. ### `howquote.txt` 2. In the first paragraph you found, above, put the example command line (showing the use of quotes around the `*.txt` argument that contains a GLOB character) into file `howquote.txt` in your [Base Directory]. The file must contain just the example command line text after the `e.g.` and it will be one line, three words, 19 characters. If the count is wrong, *look in the file* to see what is wrong with the text. Does the file contain *exactly* the same text as the course notes? If not, edit the file and fix it. **Hints:** The best way to put this example line in the file is to use a Linux text editor, or you can use the `cat` keyboard and EOF method from section 5.5a in [Worksheet #05 HTML]. Read this Warning: > **Warning:** It is tricky to use `echo` with redirection to put this > command line into the file because the line contains shell metacharacters. > You can't just stick `echo` on the front of a command line that contains > shell metacharacters such as quotes; the shell will remove the quotes > before the `echo` command runs. You will need special [Quoting] to make it > work. You will need to hide all the shell metacharacters in the command > line from the shell. Make sure the command line echoes correctly to the > screen before you try to redirect it into the file. **You can only redirect > what you can see!** Use a text editor instead! Run the [Checking Program] to verify your work so far. ### Absolute Path to the Maze 1. Use the absolute pathname of the `maze` name in the [Source Directory] as an argument to `ls` along with an option that shows the *long information* about the pathname. (You already saved this maze pathname in a file, above.) Use the actual absolute pathname that you saved, not a shell tilde short-cut for an absolute pathname. (Do not start the name with a tilde.) **Do not put a trailing slash on the pathname.** **Hints:** You should see exactly one line of output. You have the right option to `ls` if the first word of the output is `lrwxrwxrwx`, indicating that `maze` is a symbolic link, not a directory. If the `ls` long listing gives you a directory listing full of files instead of one line starting with `lrwxrwxrwx`, make sure you are using the right option to `ls` and the correct [Source Directory] path from this assignment and not any previous assignment. The command you use should use one option and one absolute pathname (with no trailing slash). We will learn more about symbolic links in a future assignment. For now, note that the `maze` symbolic link has an arrow that leads to the same directory maze used in [Assignment #03 HTML]. (See that assignment for details on the size of this maze.) ### `lscmd.sh` 2. Save the full and exact `ls` command line you just used into file `lscmd.sh` in your [Base Directory]. Pay attention to the file name extension in this file. Running the command by typing `sh -u lscmd.sh` should print the long information about the `maze` symlink. ### `infomaze.txt` 3. When you have the correct `ls` command line that generates one long line of output, redirect and save the output (one line) into file `infomaze.txt` under your [Base Directory]. Run the [Checking Program] to verify your work so far. ### Finding names starting with *abcd0001* Again, in a manner similar to your previous assignments, you must find files in this maze, using the maze as the *starting directory*. The **symbolic link** requires some special handling, because the command that recursively finds files *does not follow symbolic link arguments on the command line* without using an option. You must choose one of these methods to search this symbolic link to the maze (choose one): a) **Method 1:** Use an option to the finding command that makes it follow symbolic links only *while processing the command line arguments*. **Hint:** RTFM, search for `while processing`, and do **not** use the `-L` option, **OR** b) **Method 2:** Make the `maze` your current directory and then recursively search the current directory. (A current directory can never be a symbolic link -- it must be a real directory.) You will choose *one* of the previous two *starting directory* methods to reach the maze when you start searching, below. 1. As you know from a previous assignment, this `maze` contains many hidden sub-directories. With this maze as a *starting directory* using one of the two above methods, use a single command (no pipes needed) to recursively find *all* pathnames with a **basename** that begins with your eight-character userid at the *start* of the name. For example, if your userid were *abcd0001* then you might match and output pathnames containing basenames such as `abcd0001` and `abcd0001YYY` but *not* `XXXabcd0001` or `XXXabcd0001YYY` or `abcdYYYY` where *XXX* and *YYY* can be any non-empty strings of characters. Your own userid must start every basename. Your single recursive command should find exactly 23 pathnames. **Hint:** You must use a single command (not a pipeline) that is good at [Finding Files] by a *basename* pattern to do this. Do not try to use `cd` and `ls` to find all the files; the maze is really, really big. **Hint:** You have previously used this recursive command many times without a pattern for the **basename**. This task requires you to pass to the command a GLOB pattern that matches your userid followed by *zero or more characters*. *You must hide the GLOB pattern from expanseion by the shell, so that the shell passes the pattern to the command.* **Hint:** If you don't find any pathnames, re-read the section on the two **Methods** for the *starting directory*, above. **Hint:** If you only find a few pathnames, or you get an error message from `find` such as `find: paths must precede expression`, re-read the section on **Quoting the GLOB Pattern**, above. 2. When you see all 23 pathnames on your screen, take the same single command you used to recursively find the names above and modify it to use the expression that makes the command show the full detailed attribute information about the names (including permissions, owner, size, date, etc.) instead of just the pathname. Use the same command; just remove `-print` (the default) and add the right expression. You will know you have the right expression if the output of the command is 23 lines and approximately 256 words (instead of 23 words). **Hint:** You know which expression to use from your answers in [Worksheet #02 HTML] and [Worksheet #03 HTML] and from reading the **detailed attribute information** paragraph at the end of Section 2 of the [Finding Files] notes. You may want to review using pipes in [Worksheet #05 HTML] and [Redirection and Pipes] to do this next item. ### `foundmaze1.txt` 3. Pipe the 23 lines of pathname output of the above command into a sorting program and put the *sorted* output into file `foundmaze1.txt` under your [Base Directory]. The sorted file will still contain exactly the same number of lines and words as you counted, above. ### `findcmd1.sh` 4. Put the entire above two-command pipeline with redirection that you just used, into file `findcmd1.sh` in your [Base Directory]. Pay attention to the file name extension of this file name. **Hint:** Make sure the command you save in the file includes both the pipeline and the output redirection. If you run the command file using `sh -u findcmd1.sh` you should see no errors and no output on your screen. (All the output should go into the `foundmaze1.txt` output redirection file.) **Hint:** The best way to put this command line in the file is to use a Linux text editor, or you can use the `cat` keyboard and EOF method from section 5.5a in [Worksheet #05 HTML]. Read this Warning: > **Warning:** It is tricky to use `echo` with redirection to put this > command line into the file because the line contains shell metacharacters. > You can't just stick `echo` on the front of a command line that contains > shell metacharacters such pipes; the shell will execute the pipes before > the `echo` command runs. You will need special [Quoting] to make it work. > You will need to hide all the shell metacharacters in the command line from > the shell. Make sure the command line echoes correctly to the screen before > you try to redirect it into the file. **You can only redirect what you can > see!** Use a text editor instead! Run the [Checking Program] to verify your work so far. ### Finding names containing *abcd0001* anywhere 1. Searching this same maze, use a single command (not a pipeline) to recursively find all pathnames with a **basename** that contains your eight-character userid *anywhere* in the name. For example, if your userid were *abcd0001* then you might output pathnames containing basenames such as `abcd0001`, `abcd0001YYY`, `XXXabcd0001`, and `XXXabcd0001YYY` where *XXX* and *YYY* can be anything (zero or more characters). Your own userid will be somewhere in every basename. Your single recursive command should find exactly 47 pathnames. **Hint:** See the hints for the previous section. This command line is a simple modification of the previous one. 2. When you see all 47 pathnames on your screen, take the same single command you used to find the names above modify it to use again the expression that makes the command show the detailed attribute information about the names, as you did above. You will know you have the right expression if the output of the command is 47 lines and approximately 535 words (instead of 47 words). ### `foundmaze2.txt` 3. Pipe the 47 lines of pathname output of the above command into a sorting program and put the *reverse*-sorted output into file `foundmaze2.txt` under your [Base Directory]. The *reverse-sorted* file will still contain exactly the same number of lines and words as you counted, above. ### `findcmd2.sh` 4. Put the entire above two-command pipeline with redirection that you just used, into file `findcmd2.sh` in your [Base Directory]. **Hint:** See the hints for the previous section. Make sure the command you save in the file includes both the pipeline and the output redirection. Run the file to make sure the saved command works. Run the [Checking Program] to verify your work so far. Three different O/S Text Files -- Unix, Windows, Macintosh ---------------------------------------------------------- You need to understand [Finding Files] and [Text File Line End Differences] to do this task. 1. Somewhere under the `warez` directory in the [Source Directory] you used earlier for the WAREZ problem are exactly three non-empty files whose names contain your userid (lower-case) somewhere (anywhere) in the name. (Most of the other files in the WAREZ directory whose names contain your userid are empty files.) Use a command to recursively find and display these three non-empty (size larger than zero) files with your userid anywhere in the name. **Hints:** What command finds files based on expressions that can include both **size** *and* a **basename** that can be a GLOB-style pattern? You have used this command many times this term. See the end of [Worksheet #02 HTML] and the "multiple expressions" example in [Finding Files]. You will find your userid mentioned inside each file, but because the files are not all Unix/Linux text files, some of the text content may not display correctly on your terminal screen. The `less` command is better than `cat` when displaying files containing strange (e.g. unprintable) characters, but see also the "show-nonprinting" option to `cat`. ### `3filesOS` 2. When you know the three pathnames, manually copy each of these files (preserving modify times) to a new directory named `3filesOS` that you must create in your [Base Directory]. **Hints:** Copy the entire file contents, not just the file names. Since there are only three file names, you can use your mouse to copy-and-paste the three long file names you need to copy, once you know their names. Be careful to use quoting to hide any blanks in the names from the shell. *(Optional advanced use: You can also read this optional material on a better way to [use find -exec and xargs].)* ### `Unix` `Windows` `Macintosh` 3. In your `3filesOS` directory, determine which operating system created each of the three non-empty files. Rename the Unix/Linux file to be `Unix`, the Windows file to be `Windows` and the Macintosh file to be `Macintosh`. **Hints:** In [Assignment #02 HTML] you used a command that can determine file type to identify the text inside a `date.txt` file. You will also find this command listed under Week 02 in the [List of Commands][List of Commands You Should Know] in your notebook. Use this command and the notes on [Text File Line End Differences] to identify the special line endings of the Windows and Macintosh files. Run the [Checking Program] to verify your work so far. Appending to files ------------------ You need to understand [Redirection and Pipes] to do this task. ### `appendfile` 1. Count the lines, words, and characters in the file `services` under the `/etc` directory and put the count in file `appendfile` under your [Base Directory]. (Use the absolute pathname of the `services` file when you count and do not use any pipes.) The file `appendfile` should contain one line containing three numbers and an absolute pathname at the end (four words, 32 characters). There is no file extension on this output file; Linux doesn't care. 2. Extract just the last line of the same `services` file and append this one line to the end of the `appendfile` file, so that the file `appendfile` now has two lines in it (the word count line, and the last line of `services`), 7 words, and 49 characters. Do not use any pipes. **Hint:** You know a command that shows any number of lines at the end of a file. Review your work in [Worksheet #05 HTML] and the notes on [Redirection and Pipes]. 3. Append the count of the lines, words, and characters in the file `protocols` in the `/etc` directory to the end of file `appendfile`, so that the `appendfile` file now has three lines in it, 11 words, and 79 characters. (Use the absolute pathname of the `protocols` file when you count and do not use any pipes.) 4. Extract just the first line of the same `protocols` file and append just this one line to the end of the `appendfile` file, so that the file `appendfile` now has four lines in it, 15 words, and 105 characters. Do not use any pipes. **Hint:** You know a command that shows any number of lines at the start of a file. Review your work in [Worksheet #05 HTML] and the notes on [Redirection and Pipes]. Confirm that the word count of the `appendfile` file gives `4 15 105`. If you see the right number of lines but the other values differ, go back and re-read all the words in the sentences above, especially the sentences that start with the words "Use the". Run the [Checking Program] to verify your work so far. Searching System Log Files: counting refused IP addresses --------------------------------------------------------- The [Course Linux Server] is on the open Internet and is under constant attack on its SSH login port. The **Denyhosts** intrusion protection system locks out attacking IP addresses so that they are refused when they try again. We will find the most common refused IP addresses. You need to understand [Redirection and Pipes] to do this task, especially the section on [**Using successive filters in pipes**]. The course notes file [Selecting Fields with `awk`] explains how to use the command that extracts fields from lines. 1. In the section [Using successive filters in pipes][**Using successive filters in pipes**] under the sub-heading [Example 2: Count IP addresses used in break-in attempts] copy the six-command `fgrep` pipeline and modify it as follows: a) If necessary, change the month in the example from `Jan` to be the first month of the current academic term. The quoted string must be three letters, one upper-case, with a space following. b) Add on the end of the pipeline, after the `sort` command, a seventh filter command that limits the output on the screen to the first six (6) lines. Only six lines should display on your screen when you run the pipeline. **Hints:** Do not change any other parts of the existing six commands in the pipeline. All you need to do is (possibly) change the month and add a seventh filter command. For January 2017 the first line of output will be `10041 (218.65.30.46)` and the last line (of six lines) will be `1654 (218.65.30.156)`. ### `refusedpipe.sh` 2. When the output is correct, use a text editor to put the new seven-command pipline you used into the file `refusedpipe.sh` in the [Base Directory]. (Put the actual pipeline into the file, not the output.) You can put the pipeline on separate lines with backslashes at the end of each line to hide the newlines, as shown in the notes, or you can remove the backslashes and put all seven commands of the pipeline on one long line. Typing `sh -u refusedpipe.sh` should print the six most active attack IP addresses for the one month on your screen. If it doesn't do this, you haven't copied the command line correctly. Check it! > You can debug your script file by running it like this: > `bash -ux refusedpipe.sh` and making sure you see seven commands > execute before the six lines of output appears. 3. Edit the `refusedpipe.sh` file and add to the end of the file, underneath your seven-command pipeline, exactly seven numbered shell comments that explain briefly and **in your own words** the meaning of each of the seven commands used in the pipeline, using the exact comment format described below. Shell script comments start with the number-sign (or hash-tag) character `#` and extend to the end of the line. The seven numbered comment lines must have a syntax similar to this (though this is the wrong pipeline and wrong comments to use for this task): last idallen | awk '{ print $3 }' | grep '^[0-9]' | sort | uniq | wc -l # 1. last idallen: show last login lines only for user idallen # 2. awk '{ print $3 }': display only third field (IP address) # 3. grep '^[0-9]': select only lines starting with a digit # 4. sort: put IP addresses into sorted order # 5. uniq: throw away duplicate adjacent IP addresses, leaving only unique # 6. wc -l: count the number of unique IP addresses (number of lines) **Comment Format:** Since there are **seven** commands in your script pipeline, you will need to write exactly **seven** numbered comment lines to explain them. As you see in the above example, each of the seven comment lines starts at the left margin with the `#` comment character (no spaces in front), followed by a space, number, a period, space, the pipeline command name and options to which the comment refers, and then your own comment text written **in your own words**. Each comment text is written **in your own words** to explain what the command does in the pipeline. Do not copy words; write your own. Follow the syntax shown in the above example, and use your **own** words (don't copy mine). Including the seven comment lines, your `refusedpipe.sh` file will be at least eight (or more) lines long. Run the [Checking Program] to verify your work so far. Searching System Log Files: counting attacks -------------------------------------------- The [Course Linux Server] is on the open Internet and is under constant attack on its SSH login port. The **Denyhosts** intrusion protection system locks out attacking IP addresses and logs the event. We will find the month in 2016 with the most locked out IP addresses. 1. Write a command to count the number of lines containing the string `new denied hosts` in the `denyhosts-2016` log file on the CLS. You should find `1560` matching lines in the file. **Hints:** This log file is in the same directory as the `auth.log` file used in the previous item and in most of the [Weekly Class Notes]. Use the absolute pathname of the log file in your command line; do not change directories. **Hints:** Look at the contants of the log file before you begin. My solution used one command name with no pipes needed. I used an option to the text searching command that made it count the number of matching lines, as shown in the weekly course notes. ### `denycom1.sh` 2. When the output is correct, put the command line you used to generate the number `1560` into file `denycom1.sh` in the [Base Directory]. Typing `sh -u denycom1.sh` should print the number `1560` on your screen. If it doesn't do this, you haven't copied the command line correctly. Check it! > You can debug your script file by running it like this: > `bash -ux denycom1.sh` and making sure you see the correct command > execute before the output appears. 3. Write a command pipeline (using pipes) to count the number of lines containing the string `new denied hosts` in only **September 2016** in the `denyhosts-2016` log file on the CLS. You should find 98 matching lines to count and the output should be the number 98. **Hints:** The sub-section [Example 1: : Count ssh break-in attempts in January] given in [Using successive filters in pipes][**Using successive filters in pipes**] explains how you might find some lines in the `auth.log` file that were created in January. Apply what you learn there to solve this problem. Before you try, look at the `denyhosts-2016` file and find out what format it uses to represent the date "September 2016". You can't just look for the text "September 2016" in the file; it's not there. Look into the file to see the actual date format and create a filter command to search for that date format and count the lines. My solution used two command names with one pipe between. The second command used an option that counted the number of matching lines, as shown in the weekly course notes. ### `denycom2.sh` 4. When the command pipeline is correct, put the command pipeline you used to generate the number `98` into file `denycom2.sh` in the [Base Directory]. Typing `sh -u denycom2.sh` should print the number `98` on your screen. If it doesn't do this, you haven't copied the command line correctly. Check it! > You can debug your script file by running it like this: > `bash -ux denycom2.sh` and making sure you see the correct commands > in the pipeline execute before the output appears. 5. Using your shell history and the command you used in the previous item, modify and redo the command a few times to manually find the number of denied hosts in each month in 2016. Use this to determine the month with the largest number of denied hosts (289). **Hint:** It's one of the months after June. ### `denyhosts.txt` 6. When you find the month with the largest number of denied hosts, Put the first five lines and the last five lines of log entries for this month into file `denyhosts.txt` in the [Base Directory]. **Hint:** Use a command pipeline to generate the first five lines of log output for this month and save them, then modify the command pipeline slightly to generate the last five lines of log output for this month and append them to the file containing the first five lines. That is your answer. The first five lines should be from the start of the month and the last five lines should be from the end of the month. The word count of this ten-line file should be: `10 100 847` and the `sum` should be `04377`. Run the [Checking Program] to verify your work so far. When you are done ----------------- That is all the tasks you need to do. 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. Your instructor will also mark the [Base Directory] in your account on the due date. Leave everything there on the CLS. Do not delete anything. 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 `assignment05check` 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/cst8207/17w/assignment05/assignment05check You will learn of ways to make this shorter in future assignments. 2. When you are done, 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 `assignment05.txt` in your [Base Directory] on the CLS, like this: $ ~idallen/cst8207/17w/assignment05/assignment05check >assignment05.txt $ less assignment05.txt - Use standard output redirection with that *exact* `assignment05.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; the format is fixed. - 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 `assignment05.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 or open and save this file on your local computer! 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 `assignment05.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 **assignment05** 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 `assignment05.txt` file from your local computer. Make sure the assignment file has the correct name on your local computer before you attach it. Attach *only* your `assignment05.txt` file for upload. Do not attach any other file names. 5. After you have attached the `assignment05.txt` file on the *Upload Assignment* page, scroll down to the bottom of the page and use the *Submit* button to actually upload your attached `assignment05.txt` file to Blackboard. 6. Submit the file exactly as uploaded from the CLS. 7. Do not submit an empty file. Do not submit any other file names. Use only *Attach File, Browse My Computer* on the *Upload Assignment* page. Do not enter any text into the *Write Submission* or *Add Comments* boxes on Blackboard; I do not read them. Use only the *Attach File, Browse My Computer* 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) Click on the *Download* button to open and view the file you just uploaded. **MAKE SURE THE FILE YOU JUST UPLOADED HAS YOUR MARKS IN IT!** e) **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.) f) Make sure you have used *Submit* and not *Save as Draft*. I cannot mark draft assignments. Make sure you *Submit*. You will also see the *Review Submission History* page any time you already have an assignment attempt uploaded and you click on the underlined **assignment05** 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, Browse My Computer*. 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!** -- | 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]: assignment05.txt [hyperlink URLs]: indexcgi.cgi#Important_Notes__alphabetical_order_ [Assignments]: indexcgi.cgi#Assignments [Worksheet #04 PDF]: worksheet04.pdf [Worksheet #05 PDF]: worksheet05.pdf [Checking Program]: #checking-marking-and-submitting-your-work [Remote Login]: 110_remote_login.html [Course Linux Server]: 070_course_linux_server.html [The Unix/Linux Shell]: 120_shell_basics.html [Shell GLOB Patterns]: 190_glob_patterns.html [Redirection and Pipes]: 200_redirection.html [Worksheet #04 ODT]: worksheet04.odt [Worksheet #04 HTML]: worksheet04.html [Worksheet #05 ODT]: worksheet05.odt [Worksheet #05 HTML]: worksheet05.html [List of Commands You Should Know]: 900_unix_command_list.html [Base Directory]: #set-up-the-base-directory-on-the-cls [Copies of the CST8207 Course Notes]: 070_course_linux_server.html#copies-of-the-cst8207-course-notes [Worksheet #03 HTML]: worksheet03.html [**You can only redirect what you can see.**]: 200_redirection.html#you-can-only-redirect-what-you-can-see [Source Directory]: #the-source-directory [verify your GLOB patterns before using them]: 190_glob_patterns.html#verifying-glob-patterns-before-using-them [Quoting]: 440_quotes.html [Finding Files]: 180_finding_files.html [Assignment #03 HTML]: assignment03.html#finding-files-in-a-maze [Worksheet #02 HTML]: worksheet02.html [Text File Line End Differences]: 015_file_transfer.html#text-file-line-end-differences [use find -exec and xargs]: 185_find_and_xargs.html [Assignment #02 HTML]: assignment02.html [**Using successive filters in pipes**]: 200_redirection.html#using-successive-filters-in-pipes [Selecting Fields with `awk`]: 187_selecting_fields_awk.html [Example 2: Count IP addresses used in break-in attempts]: 200_redirection.html#example-2-count-ip-addresses-used-in-break-in-attempts [Weekly Class Notes]: indexcgi.cgi#Weekly_Class_Notes [Example 1: : Count ssh break-in attempts in January]: 200_redirection.html#example-1-count-ssh-break-in-attempts-in-january [File Transfer]: 015_file_transfer.html [EMail]: mailto:idallen@idallen.ca [Pandoc Markdown]: http://johnmacfarlane.net/pandoc/