CSCI 330 - Assignment 2 Man pages
(Total points for complete assignment 50 points)
Due Monday 25 Sept. 2017, Mid-Night

For this assignment, create a 330 directory.

mkdir 330

and change permissions so only you can access it, either

chmod 700 330
or

chmod u=rwx,go= 330

#Because there is nothing to the right of go= , this turns off all permission for group and other.

Change to your 330 directory and do all work there.

Use the man command to read about each command and desired feature listed in the problems below. When you believe you have the right answer, use one of the editors and enter the answer into a file called assn02.sh You can run the answers from your file to test if they are correct. If an answer is wrong, simply edit your answer and re-run the command.

Start by creating assn02 as an empty executable shell file. Use the following commands at the prompt:

touch assn02
chmod 700 assn02

To use the new file for the assignment, open the assn02.sh file, enter the command, options, and arguments for the problem you are working on, save the file and quit.

You have created a shell script file.

To test the command, at the prompt, enter:

./assn02.sh

If the syntax is correct, your command will run and you can check the output to see if your option choices are correct. If you find something is incorrect, open the file, edit the command line, save and quit, and run it again. Once you have answered a problem, comment out the command line for that problem (see below) and work on the next problem. By commenting out each problem as you solve it, you will be able to put all solutions in the one file and still test them one by one.

The assn02.sh file should contain the following information.

The first line in assn02.sh should contain on the line by itself (no spaces or tabs).

#!/bin/bash

This is sometimes referred to as the shebang, and it indicates to the command interpreter how to interpret commands found in the file.

The subsequent lines in the file may be command sequences and/or comments.

To find a solution to a particular problem, use man on the command being studied. The man page gives a basic synopsis of what a command does and available options that modify that behavior.

It lists both the standard Unix style options, single hyphen followed by a character, and the Linux style options, a double hyphen and a descriptive word.

Where possible use the single hyphen version. But is it possible that a particular option is only available as a Linux style option.

For each problem :

There should 1 or more comment lines stating the problem question. Comment lines begin with a #

A separate line containing the command and option[s] that answers the problem in a run-able syntax. Do not put anything but a valid answer on the answer line.

One or more blank lines after each answer.

Work on one problem at a time. When you believe you have the correct answer after testing, comment out the answer and start working on the next problem. Use a double ## at the beginning of the command. This will make it easy for the TA to tell the difference between comment lines and your code.

You can save some typing by creating a couple of shell variables to hold path to the test data and the check data directories . Under the shebang line, enter the following.

check="/home/hopper/berezin/Data/assn02_d"

You may use these variables rather than typing long path info in your command sequences. Because these are local, when the shell-script terminates, they will be forgotten each time the program terminates.

You may use different variable names but, keep in mind, PATH is already in use. When creating local temporary variable, using lower case is common practice. Unix is case sensitive, so you must reference the variable exactly like you declared it.

Redirect output to a separate file for each command. Use the format 1a.out, 1b.out, etc. for each command. This will allow you to use diff to compare your output with a set of check files I'll set up.

A solution will look something like this. Note the use of $data variable and redirection. :

assign

The answer file will look something like this: assn02.ex

Remember, when using a local variable to remember the path to the test data, DON'T use the ~berezin/Assns or /home/hopper/berezin/Data before the filename. That is what the local variable provides.

After diff checks your output, take the time to actually look at the output, to familiarize yourself with what the commands/options do. For small files, you can cat the file to the screen, for larger files, use less.

Problems

1. cat - concatenate the contents of the file or files listed as arguments to standard output.
Apply cat to ~berezin/Data/data02.txt

What option or options

1b. numbers the lines printed out BUT skips numbering blank lines.

1c. indicate where tabs are with ^I and where form-feeds are with ^L.

1d. prints a $ at the end of the text line. This is good for spotting trailing blanks.

2. diff - diff compares two text files given as arguments and indicates the differences between them. First run diff with the specified arguments but without any option[s] to have see the default behavior of diff. Use data02.dif1 and data02.dif2 for the two files to differentiate.

Take moment to look at diff.txt using the following three commands.

cat diff.txt

cat -vet diff.txt

less diff.txt

Then for each option question, compare $data/data02.dif1 to $data/data02.dif2 using the option that matches the problem. The files have been designed so that certain lines will disappear from the output of diff if they match according to the correct option choice. Remember to redirect output to the .out files.

You can view the output files with less. Because these files contain some non-printable characters, you will warnings like the following :

"2a.out" may be a binary file.  See it anyway?

Hit the y key to continue.

What option or options

2b. ignore all blanks.

2c. ignores trailing blanks and treats other blanks as being equal.
Note that there is a slight difference in the output between the two problems (b and c) above.

2d. Produces a script that can be used by the ed editor to recreate the second file from the first file. Your .out file will probably be blank.

3. finger - finger retrieves information about users on a system. When run by itself, it displays minimum information about their login session.

On the other hand, when applied to a specific user, it gives additional information, including a user's .plan file, if it has been created. It will do this even if the user is not logged on.

What option or options

First run finger on user berezin with no options.
Then run it again with the option to suppress .plan

finger with no options will do a minimal listing of all users currently logged in. But it will not show any plans. Run finger with no arguments or options.

3b. Find the option that will make it show the more detailed display including the .plans if a logged in user who has created one.

Because the users logged in at any time constantly changes, the output file will not match mine. The output may be rather long, so use less to view the output file

Then look at my output from the command line. Type in the following or copy and paste it on the command line from this web page. :

less /home/hopper/berezin/Data/assn02_d/3b.out

4. grep - global regular expression parser. grep will search one or more files and find all lines that contain a string of characters that match a pattern (regular expression) defined by user. Look for the string "assign" in the file or files specified in the problems below. Your command will look something like:

You can do the following in the answer file to save some typing if you know how to copy and paste.

In preparation, run the grep with no options separately on three files, data02u.txt, data02n.txt, and data02ps.txt.

Immediately follow each run with :

echo $?

This will show you the default results of the command's execution and also show its success status.

echo $? displays the success status of the last run command, 0 = success, a non-zero is failure. Depending on the program, a specific value tells what the failure is.

Note status.

Do NOT run any other commands between the grep and the echo $?

For grep, what option or options

Do the three greps above with the chosen option[s].

Remember to print the status also. Note that the output may change but the status should be consistent with the original test runs.

4b. does not print any standard output (matches).

Do the three greps above with the chosen option[s].

4c. count the number of lines that contain the string assign
Search ~berezin/Data/data02ps.txt

4d. ignore the case of the string being searched for.
Search ~berezin/Data/data02ps.txt

4e. print all lines that do NOT contain the regular expression.
Search ~berezin/Data/data02ps.txt

4f. print just the filename of the file containing the string matching the regular expression. Use
~berezin/Data/data02*
for the file name. Make sure you include the asterisk after data02

5. tail - display the last few lines of a text file. How many lines or where to start displaying from can be controlled by various options. Apply tail to ~berezin/Data/taild. Start by trying it with no options.

What option or options

5b. lets you specify by character count where to start printing from. Print from the 13th character from the end. Count the number of characters in the output. You will find that line feeds are counted.

5c. lets you specify by character count where to start printing from. Print from the 13th character from the beginning. You will find that line feeds are counted.

6. ls - list the contents of the current or specified directory file. Its options determine how much and in what format that information is revealed. Apply ls to ~berezin/Data/d2 directory.

What option or options

6b. allows you to specify a directory name and displays the permissions of the directory rather than the permissions of contents of that directory.

6c. puts special symbols after directories, executables and linked filenames when listing them.

6d. displays the inode number next to the filename.

7. sort - sort the contents of one or more text files. Apply sort to ~berezin/Data/data02s.txt

What option or options

7b. specifies the name to send the output to instead of to standard out.
Use mysort as the name of your output file

7c. causes lower case letters to be listed together with the upper case letters.

7d. sort on the second word on the line. Use the data02ps.txt file.
The second word is a number but it will still work. Note how it sorts. All the 1's come first, then all the 2's.

Use data02ps.txt for 27.

7e. sort on the second word on the line but also sort so is numerically correct, 1-10 followed by 11-99, followed by 100-999, etc.

Use data02ps.txt for 27.

8. od - (octal dump) displays the contents of a file, text or binary, in a readable format. By default, od displays each byte as a three digit octal value, even readable text.
Use traditional options.

Apply od to data02h.txt.

What option or options

9b. displays the bytes of a file as hexadecimal numbers.

9c. displays the bytes of a file as decimal (base ten) numbers.

9. pr - pr(int) (display) the contents of a text file formatted for printing. Usually breaks pages at 66 lines rather than 24 (screen length) and puts a header with a page count..

Apply pr to the output of ls on /bin

What option or options

9b. lists line with a three digit wide line count in front and separate line count from line contents with a > Be careful to quote the >

10. tr - tr(anslate) characters in a text file into another set of characters. tr usually takes two lists of characters and matches them. If a character in the text file is found in the first list at a particular position, it is replaced by the character found in the second list in the exact same position. Besides translating characters into other characters, tr can also delete a list of characters.

Important 'feature' of tr is that it reads from standard input, keyboard, and write to standard output, screen. So you must use redirection in, <, to specify file being translated and redirection out, >, to specify the file to store results in.

Apply tr to /etc/profile

What option, options, and/or arguments

10b. translate lower case a through f to upper case B through G.

11. cut - cut specific columns of data from a file.

What option or options

11b. get the sixth-field (word) from the file /etc/passwd. Use colon : as a delimiter. You may have to quote the colon.

12. date - displays today's day and date up to the second in a human friendly manner. However, what info is shown and in what format can be varied. Read both the date man page and the strftime (string format for time). The second man page represents not a command but a function that date invokes and it lists all formats available.

What option or options

12b. prints only the hour data02.txt was last modified.

13. ps - lists the processes (commands) running on the system.

What option or options

13b. lists every single process running on the system with a full listing.

13c. lists only processes not related to a terminal.

14. stty - set terminal type allows user to view or set the properties of the terminal. For example, you can change the definition of the erase key or reset the terminal. stty treats all arguments like options and its syntax differs from other commands. For many of the options, you can give the option with or without a hyphen. Without the hyphen, the option turns on a feature, with the hyphen, the option turns off a feature.

Run stty with its options.

What option or options

(44)b. resets the terminal to a reasonable set of values. This may be useful if your terminal becomes garbled because of a bad connection or cat-ing an executable file.

NOTE : if you run this, you may find you have to log-out and back in to get your shell to behave normally. This is useful when things go bad, but the result is not optimal.

15. split - splits a file into multiple files. Complement of cat, split breaks a file into smaller files.

Split will generate a set of files, xaa, xab, xac, etc. so that is what to look for when the file is run. Make sure you Don't any other files starting with x and do a rm x* between each option trial.

For steps a-c, use data02.txt

What option or options

# You should see 7 files xaa, xab, xac, xad, xae, xaf, xag. # Running wc x* in your work directory, should give :
7 23 219 xaa 7 27 281 xab 7 21 211 xac 7 36 347 xad 7 21 197 xae 7 22 218 xaf 42 150 1473 total

(47)b. splits file into files where the lines are at most 10 characters long. If end of line encountered before 10th character. Start next line in new file.
# Run ls x*. You should see 163 files, xaa through xgg.
# If you do a wc x*, most of the files should have 10 characters.
# No example

(48)c. splits file into 3 files.
# Run wc x*, you should get :
13 50 491 xaa 13 50 491 xab 16 51 491 xac 42 151 1473 total

(49)d. splits file into files of 12000 bytes. Use the data02ps.txt file, use the size modifier to specify thousands.
# Run wc x*, you should get :
170 1565 12288 xaa 141 1233 9166 xab 311 2798 21454 total

Note : the modifiers are binary based so one thousand in binary is actually 1024 and the size of the resulting files will reflect this.

Read the SIZE and CHUNK sections at the end of the options list in the man pages.

Handing in the assignment

For this assignment, you will create the file assn02 with your answers recorded in it as a set of executable lines.

Email the results to me on turing or hopper.

mutt -s assn02 berezin < assn02

-s assn02 : sets the subject line.

berezin : my account ID on the local system

< assn02 : redirects input input from your assignment rather than from the keyboard.

Note that if this is successful, there will be no response. I will start reviewing my email on turing and hopper and respond when I've received something from you.