:* Understand the difference between '''absolute''' / , '''relative''' / and '''relative-to-home''' pathnames

:* Become productive at issuing Linux commands with the most efficient appropriate pathname

:* Use '''quotation''' to convert treat special characters as just '''text ''' when issuing Linux commands.

:* Understand the quotation symbols: '''Backslash \ ''' , '''single quotes ' ' , ''' and '''double quotes " "'''<br><br>

|colspan="2" style="font-size:16px;font-weight:bold;border-bottom: thin solid black;border-spacing:0px;padding-left:15px;"|Pathname Type / Filename Expansion / Quoting Reference<br>

|colspan="1" width="22%" |'''Slides:'''<ul><li>Week 3 Lecture 1 Notes:<br> [https://wiki.cdot.senecacollege.ca/uli101/slides/ULI101-3.1.pdf PDF] | [https://ictwiki.cdot.senecacollege.ca/~murrayuli101/slides/ULI101-3.1.pptx PPTX]</li><li>Week 3 Lecture 2 Notes:<br> [https://wiki.cdot.senecacollege.saulca/uli101/slides/ULI101-Week33.2.pdf PDF] | [https://ictwiki.cdot.senecacollege.ca/~murray.saululi101/uli101slides/ULI101-Week33.2.pptx PPTX]<br></li></ul>

| style="padding-left:15px;" |'''Pathname / Filename Expansion:'''

| style="padding-left:15px;"|'''Quoting Special Characters:'''

'''Linux Commands:'''

|colspan="1" style="padding-left:15px;" width="30%"|'''Instructional Videos:'''<ul><li>[https://www.youtube.com/watch?v=ephId3mYu9o Pathname Types]</li> <li>[https://youtu.be/5FQnehwzwSM Filename Expansion Examples]</li>

Last week, we used a pathname from our home directory to create and manipulate directories and text files.<br>There are '''different types of file pathnames ''' that we can use to access a directory or text file.

''ExampleExamples:''<br><span style="color:blue;font-family:courier;">mkdir ls /bin<br>ls /home/your-user-id/uli101/examples</span>

Examples: <br><span style="color:blue;font-family:courier;">mkdir uli101ls ../../../bin</span><br><span style="color:blue;font-family:courier;">mkdir ./uli101ls examples<br>ls ../../binexamples</span>

The tilde character '''~''' stores the path of the user’s home directory <br>(i.e.'''~ = /home/current-user-id''')<br><br>You can immediately place a username after the tilde to represent another user’s home directory (for example:e.g. '''<span style="font-family:courier">'''~jane = /home/jane'''</span>''')

Examples:<br><span style="color:blue;font-family:courier">ls ~/uli101/practiceexamples<br>ls ~murray.saul/uli101/tutorials<br>~uli101/assign1notes</span>

'''NOTE:''' Deciding which '''type of pathname''' to use depends on many factors including:<br>'''knowledge of current directory''', '''knowledge of directory structure''', <br>'''currently directory location''',<br>and '''type of file management command''' that is being used.

When issuing Linux commands, it may be '''more efficient''' (less typing) to use '''filename expansion symbols'''<br>to better match files that share similar characteristics (e.g. same file extension)when issuing Linux commands.

You issued the '''ls''' command to view all of the files contained in your current directory:  <span style="color:blue;font-family:courier;>'''ls'''<br>a.txt b.txt c.txt 1.txt 2.txt 3.txt abc.txt work.txt webpage.html picture.png</span>  You now want to list just text files (i.e. files with the extension ".txt").<br>One method to do this is to issue the ls command and specify each file pathname as a separate argument:  <span style="color:blue;font-family:courier;>'''ls a.txt b.txt c.txt 1.txt 2.txt 3.txt abc.txt work.txt'''<br>a.txt b.txt c.txt 1.txt 2.txt 3.txt abc.txt work.txt</span> [[Image:globbing-demo-2.png|thumb|right|400px|'''Globbing''' is the process of expanding filenames as separate arguments that match an argument that uses a '''wildcard symbol'''<br>(such as '''*''').]]But this method is '''inefficient''': it requires a LOT of typing and knowing which filenames to include as separate arguments. You can use a special character to indicate to the Bash shell to match all files that end with the extension ".txt":

<table cellpadding="5"><tr><th style="border-bottom: 1px solid black;text-align:left;">Filename <br>Expansion <br>Symbol</th><th valign="bottom" style="border-bottom: 1px solid black;text-align:left;">Purpose</th></tr><tr><td>'''*'''</td><td>Asterisk (*) to represent '''0 or more characters'''</td></tr><tr><td>'''?'''</td><td>Question mark (?) to represent '''exactly one character (any character)'''</td></tr><tr><td>'''[ ]'''</td><td>Square brackets ([ ]) to represent and match for the <br>'''character enclosed within the square brackets'''.<br>It represents ONLY ONE character - it's like a<br>'''Question Mark (?)''' but with '''conditions or restrictions'''</td></tr><tr><td>'''[! ]'''</td><td>Square brackets containing an exclamation mark immediately after<br>the open square bracket ([! ]) to represent and match and<br>'''OPPOSITE''' character for the character enclosed within the square brackets.</td></tr></table>

There are '''3 methods''' to make those special characters '''act only like text characters''' <br>when issuing Linux commands (referred to "'''quoting'''" special charactersdisplayed in chart below): 

The best way to learn about pathname different types of file pathnames is to issue many use them while issuing<br>Linux file management commands using each type (absolute, relative, relative-to-home) and see which ones pathnames (or combinationof pathnames) is the '''<u>most </u> efficient '''<br>(i.e. requiring the '''least number of keystrokes''').

# Issue a command to '''confirm''' you are located in your home directory.<br><br>Let's create the following directory structure under your home directory by issuing the mkdir command using only absolute pathnames.<br><br># Issue the following Linux command to create the directory structure displayed to the right using '''absolute pathnames''':<br><br>'''NOTE:''' The command you issue below will be VERY LONG... just keep Just continue typing and let the text continue of separate lines. When using these absolute pathnames, start each one from the root directory (/) and Remeber to replace the text "youruserid" with your actual login Seneca-id.<br><br># Issue the following Linux command to create the directory structure displayed to the right using '''absolute pathnames''':<br><br><span style="color:blue;font-weight:bold;font-family:courier;">mkdir -p /home/youruserid/tutorial3/practice/commands /home/youruserid/tutorial3/practice/examples /home/youruserid/tutorial3/notes/lesson1 /home/youruserid/tutorial3/notes/lesson2</span><br><br># Issue the following Linux command to confirm that you properly created the directory structure:<br><span style="color:blue;font-weight:bold;font-family:courier;">tree /home/youruserid/tutorial3</span><br><br>You should notice that using absolute pathnames with this Linux command '''requires a lot of typing'''.<br>Let's '''remove ''' this directory structure, and issue the same command using a ''relative-to-home '' pathnameinstead.<br><br># Issue To remove this directory structure, issue the following Linux command (enter "'''y'''" at each prompt to remove ALL contents):<br><span style="color:blue;font-weight:bold;font-family:courier;">rm -ri /home/youruserid/tutorial3</span><br><br># Issue a command tree command as you did in '''step #4''' to confirm that the tutorial3 directory (and its contents) no longer exist. You should know how to do thisstructure has been removed.<br><br>Let's recreate # Issue the following Linux command to create the same directory structure, but use a '''using relative-to-homepathnames:<br><br>'''NOTE:''' pathname. You usually generate the ~ character by Holding down '''SHIFT''' and press the button <br>to the <u>left </u> of the number '''1''' above the text on your keyboard.<br><br># Issue the following Linux command to create the same directory structure using relative-to-home pathnames:<br><br><span style="color:blue;font-weight:bold;font-family:courier;">mkdir -p ~/tutorial3/practice/commands ~/tutorial3/practice/examples ~/tutorial3/notes/lesson1 ~/tutorial3/notes/lesson2</span><br><br>Did this command require less typing than the previous command using absolute pathnames?<br><br># Issue the '''tree''' command to confirm the directory structure was properly created.<br><br>Let's remove the '''tutorial3''' directory and its contents and issue the mkdir same command with using '''relative pathnames to create the same directory structure'''.<br><br># Issue the same command as you did in '''step 4 #5''' to remove the '''tutorial3 ''' directory and its contents safely.<br><br># Issue a Linux command to confirm you removed the '''tutorial3 ''' directory and its contents.<br><br># Issue the following Linux command to create the same directory structure using relative pathnames:<br><br><span style="color:blue;font-weight:bold;font-family:courier;">mkdir -p tutorial3/practice/commands tutorial3/practice/examples tutorial3/notes/lesson1 tutorial3/notes/lesson2</span><br><br># Issue a command to verify that the proper directory structure was created.<br><br>'''QUESTION:''' Which '''mkdir''' command (pathname type) that you performed in steps '''3''' , '''67''' , and '''911''' required the <u>LEAST</u> number of keystrokes (i.e. characters)?<br><br>

:You may think that issuing Linux file management commands are better using '''relative''' or <br>'''relative-to-home''' pathnames instead of '''absolute''' pathnames, but this assumption may that is not always be correcttrue.

:Since the '''current ''' directory location was your '''home''' directory, then it makes sense that using to use ''relative '' or ''relative-to-home '' pathnames are more efficient. On the other hand, what if we <u>changed </u> the location to a different directory? Then perhaps, using an absolute pathname would be preferable.

:When performing the next series of steps, refer to the '''tree diagram''' on the right. It is '''HIGHLY RECOMMENDED''' to always refer to a tree diagram when issuing Linux using different pathnames. Learning to reference a tree diagram on a '''quiz''', '''midterm''' or '''final exam''' can help to '''prevent errors and loss of marks!'''

# Issue Since we will be running Linux commands depending on the directory structure that you have created, issue the following Linux command to run a checking script to ensure verify you created the CORRECT directory structure displayed as in the diagramit correctly:<br><span style="color:blue;font-weight:bold;font-family:courier;">bash /home/murray.saul/scripts~uli101/week3-check-1</span><br><br># If you encounter errors , make corrections and then re-run the checking script until you receive a congratulations message.<br><br># Issue a Linux command to change to the '''examples''' directory in your recently-created directory structure.<br><span style="color:blue;font-weight:bold;font-family:courier;">cd tutorial3/practice/examples</span><br><br>

# Remembering that we are located in the '''examples''' directory, issue the following Linux command <br>using a '''relative''' pathname to display files in the /bin directory: <span style="color:blue;font-weight:bold;font-family:courier;">ls ../../../../../bin</span><br><br># Now issue the following Linux command using an '''absolute''' pathname: <span style="color:blue;font-weight:bold;font-family:courier;">ls /bin</span><br><br>Which type of pathname would be the best to use in this situation?<br><br>'''NOTE:''' Although it would work, using Using the previous command using the '''relative-to-home''' pathname would work, <br> &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; but it would look weird. Try to issue the command yourself!<br><br># Let's copy the file called ls which is contained in the '''/bin''' directory to your '''home''' directory by using the '''cp''' command. <br>First, issue the following Linux command to copy the ls command from the /bin directory to your home directory using absolute pathnames: <br><span style="color:blue;font-weight:bold;font-family:courier;">cp /bin/ls /home/youruserid</span><br><br># Now let's issue the previous command using just relative pathname (remember, our current directory location is '''examples'''):<br><span style="color:blue;font-weight:bold;font-family:courier;">cp ../../../../../bin/ls ../..</span><br><br>'''TIP:''' For relative pathnames that move up multiple parent directories such as these, it is HIGHLY RECOMMENDED <br>to view the tree diagram and check for the correct number of .. symbols. Students commonly make mistakes <br>and lose marks on these type of questions!<br><br>

# Let's copy the '''ls ''' file from the '''/bin''' directory to your <u>current</u> directory (i.e. examples): <span style="color:blue;font-weight:bold;font-family:courier;">cp /bin/ls .</span><br><br># Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">cp /bin/ls ./ls.bk</span><br><br>What does this command do?<br><br>Let's run a checking script to make certain you performed the a few of the recently-issued commands correctly.<br><br># Make certain that your current directory is '''your home directory'''.<br><br># Issue the following Linux command to run a checking script: <span style="color:blue;font-weight:bold;font-family:courier;">bash /home/murray.saul/scripts~uli101/week3-check-2</span><br><br># If you encounter errors , make corrections and then re-run the checking script until you receive a congratulations message, <br>and proceed to the next INVESTIGATION.<br><br>

# Issue a Linux command to move to the '''commandsexamples''' directory<br>(i.e. under ''practice'' directory as shown in diagram to the right).<br><br># Issue a Linux command to confirmed that you have moved to the '''commandsexamples''' directory.<br><br># Issue a Linux the '''touch''' command to create the following empty regular text files in the ''commandsexamples'' directory:<br>(note ''upper'' and ''lowercase'' letters)<br><br>

<ol><li value="4">Issue To verify that you properly created those files, issue the '''ls''' command to get a listing of files in your commands directory.following:<br><brspan style="color:blue;font-weight:bold;font-family:courier;">~uli101/week3-check-3</span><br>The output should look identical to the diagram displayed below.<br>You can refer to this listing to see all files so If you can encounter errors, then predict the output from Linux commands that use make corrections (eg. '''viewing directory contents''', '''check for correct filename expansion symbols.syntax''',<br><br>[[Image:listing-1'''case sensitivity''', '''missing files''', '''files in the wrong location''', etc.png|left|650px|thumb|]]) and then re-run the checking script<br>until you receive a congratulations message, and then continue with this investigation.<br><br><brspan style="color:red;">'''ATTENTION''':</libr><li>Before proceeding, letLearning to '''fix your mistakes's run a checking script to '' by issuing Linux commands may be required if you make certain that you created these regular files correctly:mistakes<br>Make certain that your current directory is '''in your home directory'''online tutorial.</span><br><br></li><li>Issue the following Linux '''ls''' command to run get a checking script:listing of files in your ''examples'' directory.<br><span style="color:blue;font-weight:bold;font-family:courier;"br>The output should look identical to the diagram displayed below.<br>bash /home/murrayYou can refer to this listing to see all files so you can then predict the output from Linux commands that use filename expansion symbols.saul/scripts/week3<br><br>[[Image:listing-check-31.png|left|650px|thumb|]]<br></spanbr><br><br></li><li>If What do you encounter errors, then make corrections, and then re-run think the output will be from the checking script until you receive a congratulations message, and continue in this section.<brfollowing Linux command?<br><br>'''NOTEspan style="color:blue;font-weight: To become comfortable with using filename expansion symbols, an excellent practice method is to create multiple files (you have already done that), look at the Linux command using filename expansion symbols and view the listing of files in the current directory that match and then write bold;font-family:courier;">ls ???.txt</span><br>'''Write down on a paper the expected output of commands that use filename expansion symbols. You can ''' on paper, then run '''issue the command to see the results in order ''' to check your workanswer.'''<br><br>Let's try this:<br><br></</li><li>Issue What do you think the output will be from the following Linux command: ?<br><span style="color:blue;font-weight:bold;font-family:courier;">ls ?????.txt</span><br>'''Write down the expected output on ''' on paper, then '''issue the command ''' to check your answer.<br><br></li><li>Issue What do you think the output will be from the following Linux command: ?<br><span style="color:blue;font-weight:bold;font-family:courier;">ls ??????.txt</span><br>'''Write down the expected output ''' on paper, then '''issue the command ''' to check your answer.<br><br></li><li>Issue What do you think the output will be from the following Linux command: ?<br><span style="color:blue;font-weight:bold;font-family:courier;">ls ??????[0-9].txt</span><br>'''Write down the expected output on ''' on paper, then '''issue the command ''' to check your answer.br>Did the command work?<br>What does this teach you about the character class [ ] symbol?<br><br></li><li>Issue What do you think the output will be from the following Linux command: ?<br><span style="color:blue;font-weight:bold;font-family:courier;">ls [0-9][0-9][0-9].txt</span><br>'''Write down the expected output ''' on paper, then '''issue the command ''' to check your answer. Did the command work? What does this teach you about the character class [ ] symbol?<br><br></li><li>Issue What do you think the output will be from the following Linux command: ?<br><span style="color:blue;font-weight:bold;font-family:courier;">ls [0a-9z][0a-9z][0a-9z].txt</span><br>'''Write down the expected output ''' on paper, then '''issue the command ''' to check your answer.<br><br></li><li>Issue What do you think the following output will be from the following Linux command(using character class with UPPERCASE letters)?: <br><span style="color:blue;font-weight:bold;font-family:courier;">ls [aA-zZ][aA-zZ][aA-zZ].txt</span><br>'''Write down the expected output ''' on paper, then '''issue the command ''' to check your answer.<br><br></li><li>Issue What do you think the output will be from the following Linux command (using character class with UPPERCASE lettersusing alpha-numeric characters): ?<br><span style="color:blue;font-weight:bold;font-family:courier;">ls [Aa-ZzA-Z0-9][Aa-zA-Z0-Z9][Aa-zA-Z0-Z9].txt</span><br>'''Write down the expected output ''' on paper, then '''issue the command to ''' to check your answer.<br><br></li><li>Issue What do you think the output will be from the following Linux command (using character class using alpha-numeric characters): ?<br><span style="color:blue;font-weight:bold;font-family:courier;">ls [a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9].txt*.txt</span><br>'''Write down the expected output ''' on paper, then '''issue the command ''' to check your answer.Did ALL text files get listed? Why not?<br><br></li><li>Issue What do you think the output will be from the following Linux command: ?<br><span style="color:blue;font-weight:bold;font-family:courier;">ls *.txt[tT][xX][tT]</span><br>'''Write down the expected output ''' on paper, then '''issue the command ''' to check your answer. Did ALL text files get listedthis time? Why notIf so, why?<br><br></li><li>Issue the following Linux '''NOTE:''' We have just been using filename expansion symbols just with the ls command: .<span style="color:blue;font-weight:bold;font-family:courier;">ls *br>Filename expansion symbols can be used for ANY Linux file management command (e.g.[tT][xX][tT]</span><br>Write down the expected output on paper'''cat''', then issue the command to check your answer.Did ALL text files get listed this time? If so'''more''', why?<br><br></li><li>'''NOTE:less''', '''cp''', ''' We have just been using filename expansion symbols just with the ls command.<br>Filename expansion symbols can be used for ANY Linux file management command (e.g. '''catmv''', '''morerm''', '''lessls''', etc.).<br><br>Let'''cp''', '''mv''', '''rm''', '''ls''', etc.)s get some practice issuing these other Linux file management commands.<br><br>Let's get some practice issuing these other Linux file management commands.<br><br></li></li><li>Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">file *.[tT][xX][tT]</span><br>Write down What is the expected output on paper, then issue the command to check your answer.purpose of this command? Which files are contained in this output?<br><br><li>[[Image:dir12.png|right|350px|thumb|]]Change to the '''commands''' directory using an '''absolute''' pathname.<br>(use the diagram on right-side for reference).<br><br></li><li>Issue a Linux command to confirm that you are now in the '''commands''' directory.<br><br></li><li>Issue the following Linux command(lowercase "l" NOT the number "1"): <br><span style="color:blue;font-weight:bold;font-family:courier;">cp /bin/l.* &nbsp; .</span><br>View the contents of the contents directory. What did this command do?<br><br></li><li>Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">rm *</span><br><br>View the contents of the contents directory. What did this command do?<br><br></li><li>Issue the following Linux command: <span style=(lowercase "l" NOT the number "1"):<br> <span style="color:blue;font-weight:bold;font-family:courier;">cp /bin/l? &nbsp; .</span><br>View the contents of the contents directory. What did this command do?<br><br></li><li>Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">rm l[!s]</span><br>View the contents of the contents directory. What did this command do?<br><br></li><li>Use a text editor (nano or vi) to create the file called '''ab''' in the '''commands''' directory that contains the line of text below,<br>and then save editing changes to this file:<br><span style="font-family:courier;">This is file ab</span><br><br></li><li>Use a text editor (nano or vi) to create the file called '''cd''' in the '''commands''' directory that contains the line of text below,<br>and then save editing changes to this file:<br><span style="font-family:courier;">This is file cd</span><br><br></li><li>Use a text editor (nano or vi) to create the file called '''ef''' in the '''commands''' directory that contains the line of text below,<br>and then save editing changes to this file:<br><span style="font-family:courier;">This is file ef</span><br><br></li><li>Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">cat ??</span><br><br>View the contents of the contents directory. What did this command do? Why does the output look strange?<br><br></li><li>Issue '''NOTE:''' Press the keys '''ctrl-c''' to return to the shell prompt.<br><br></li><li>Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">cat [!l][!s]</span><br><br>View the contents of >View the contents of the contents directory. What did this command do? Does the output look better? If so, why?<br><br></li></ol> : Proceed to the contents directorynext INVESTIGATION. What did this command do? Does the output look better? If so, why?<br><br></li></ol>

As discussed in the above investigation, there are some special characters that the shell uses to perform an operation<br>including the filename expansion symbol: '''*'''  There is a method make the shell '''ignore the purpose of special characters''' and treat as '''regular text'''. In this sectioninvestigation, you will learn '''three unique methods ''' to quote special characters. 

[[Image:quotation.png|right|350px|thumb|Using quotation to make the shell '''ignore the purpose of special characters''' and treat as '''regular text'''.]]# Make certain Issue a Linux command to confirmed that you are currently located still in your home the '''commands''' directory<br>(if not, change to the ''commands'' directory and confirm).<br><br>

# Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">echo * hello *</span><br><br>What happened? What is shown in addition to the text "hello". <br>Why do you think those filenames are also being displayed?<br><br>

# Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">echo $USER</span><br><br>'''NOTE''': The environment variable '''USER''' is an environment variable that stores contains the current user's login name. <br>The '''$''' character immediately followed by the environment variable name causes it to <br>expand to the '''value ''' that the variable contains. Therefore the echo command displays the current login name of the user.<br><br># Issue the following Linux command (using single quotes): <span style="color:blue;font-weight:bold;font-family:courier;">echo '* $USER*'</span><br><br>What happened? Why is the output display like this?<br><br># Issue the following Linux command (using double quotes): <span style="color:blue;font-weight:bold;font-family:courier;">echo "* $USER*"</span><br><br>What happened? Why?<br><br># Let's use quoting special characters for a couple of other commands. Move to the '''lesson2''' directory. <br>Confirm that you are currently located in the ''lesson2'' directory.<br><br># Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">cp /bin/ls .</span><br><br># Issue the '''ls''' command to verify that there are copied files in your lesson2 directory.<br><br>'''NOTE:''' Although it is NOT RECOMMENDED to create a filename using a special character (remember that file naming rulerules?), <br>we will create an empty file called "*"<br><br>

# Issue the '''ls''' command to confirm that the file called "*" has been removed in your current directory. What happened this time?<br><br># After you complete Complete the Review Questions sections to get additional practice, then work on your '''online assignment 1''' and complete '''sections 3 to 6''' labelled: '''Directory Management''' , '''Practice Commands To Create A Directory Structure''' , '''Create A Directory Structure''' and '''Practice Specifying Path Names'''. When you have completed these remaining sections, and you main menu indicates you have completed 6 out of 6 sections, then you will have successfully completed your assignment #1.<br><br>

The purpose of this section is to obtain extra practice to help with your assignment #1, quizzes, your midterm, and your final ezamexam.

https://ictwiki.cdot.senecacollege.ca/~murray.saululi101/uli101files/uli101_week3_practice.docx

# Write a Linux command using a relative pathname to list all files that begin and end with a number.# Write a Linux command using a relative-to-home pathname to list all files that begin with a number but ends with any character other than a number.# Assuming you are in your home directory. Write a Linux command using a relative pathname to view the contents of regular files whose file names only consist of 5 consecutive numbers.<br><br># Write a Linux command to display the following message:<br>*** Hello ***<br><br>