Changes

← Older edit

Tutorial4: Data Representation / Numbering Conversion / File Permissions

27,953 bytes added, 20:34, 4 September 2023

no edit summary

{{Admon/caution|DO NOT USE THIS VERSION OF THE LAB. This page will no longer be updated.|'''New version here:''' https://seneca-ictoer.github.io/ULI101/A-Tutorials/tutorial4 '''Andrew's students please go here:''' http://wiki.littlesvr.ca/wiki/OPS145_Lab_4}}

=Data Representation / Numbering Conversion / File Permissions=

===Main Objectives of this Practice Tutorial===

:* Understand ~~the importance of~~ how digital computers store data (i.e. data representation)

:* ~~Understand the purpose of~~ Define '''decimal''', '''binary''', '''octal''' and '''hexadecimal''' numbers

:* ~~Perform various~~ Manually perform '''numbering conversions''' between the '''decimal''', '''binary''', '''octal''' and '''hexadecimal''' numbering systems ~~by hand~~ (without the use of a computer or calculator)

:* ~~Identify~~ Explain the purpose of '''~~which numbering system conversion method to use~~file permissions''' ~~when required to perform a numbering conversion~~

:* ~~Understand directory and regular file~~ Explain how permissions work differently for '''directories''' as opposed for '''~~permissions~~regular files'''

:* ~~Learn how to '''set''' directory and regular~~ Change file '''permissions''' with the '''chmod''' command (both ''symbolic '' and ~~octal~~ ''absolute'' methods)

:* ~~Learn how to use~~ Use the '''umask''' command to ~~have~~ automatically assign permissions for '''newly created directories ''' and ~~files automatically set upon their~~ '''~~creation~~regular files'''

===Tutorial Reference Material===

|- valign="top" style="padding-left:15px;"

|colspan="1" width="22%" |~~Course Notes~~'''Slides:'''<ul><li>Week 4 Lecture 1 Notes: [https://~~ict~~wiki.cdot.senecacollege.ca/~~~murray~~uli101/slides/ULI101-4.1.pdf PDF] | [https://wiki.~~saul~~cdot.senecacollege.ca/uli101/slides/ULI101-~~Week4~~4.1.pptx PPTX]</li><li>Week 4 Lecture 2 Notes: [https://wiki.cdot.senecacollege.ca/uli101/slides/ULI101-4.2.pdf PDF] | [https://~~ict~~wiki.cdot.senecacollege.ca/~~~murray.saul~~uli101/~~uli101~~slides/ULI101-~~Week4~~4.2.pptx PPTX] </li></ul>

| style="padding-left:15px;" |'''Data RepresentationDefinitions:'''* ~~Definition~~[https://home.adelphi.edu/~siegfried/cs170/170l1.pdf Data Representation] * [https://en.wikipedia.org/wiki/Decimal, Decimal Numbers]* [https://en.wikipedia.org/wiki/Binary_number Binary, Numbers]* [https://en.wikipedia.org/wiki/Octal, Octal Numbers]* [https://en.wikipedia.org/wiki/Hexadecimal Hexadecimal Numbers] | style="padding-left:15px;"|'''File Permission Concepts:'''* [https://www.booleanworld.com/introduction-linux-file-permissions/ Introduction to File Permissions] '''File Permission Commands:''' * [https://ss64.com/bash/chmod.html chmod] * [https://ss64.com/bash/umask.html umask]

|colspan="1" style="padding-left:15px;" width="30%"|'''Instructional Videos:'''* [https://www.youtube.com/watch?v=4nGgqLIKU9U Numbering ~~Conversion~~Conversions]* [https://www.youtube.com/watch?v=SdgiYoOi0CY File Permissions]|} = KEY CONCEPTS = ===Data Representation===[[Image:binary-number1.png|right|200px|https://creativecommons.org/licenses/by-sa/3.0/ cc]]Digital computers are '''electronic devices''' that contain a series of '''circuits''' and voltage levels that can store / represent data. '''Binary numbers''' can represent those series of circuits with voltage levels. Those binary numbers are combined in a sequence to form a '''byte'''. Bytes are used to represent numbers or characters. IT professionals may need to perform '''numbering conversion''' to use with ''programming functions'' or ''OS commands'' to perform common operations on a computer system. ''IT Professionals that Use Data Representation:'' * ''Network Specialists'': Building Large Networks via Sub-netting* ''Programmers:'' Sending information over networks, files* ''Web Developers:'' Setting color codes for webpage background or text * ''Unix/Linux System Administrators:'' Setting ''permissions'' for files and directories ===Numbering Conversion Methods=== ====Method 1: Binary to Decimal </ ~~Decimal~~ u>==== [[Image:convert-bin-decimal.png|thumb|right|350px|Performing a '''binary''' to '''decimal''' conversion.]]When converting '''binary''' numbers to '''decimal''' numbers, perform the following steps: # Write down the binary number. # Starting from the '''right-side''', draw '''L''''s below the binary number moving to the left (refer to diagram on right). # Starting on the ''rightmost'' "'''L'''", multiply the value (placeholder) by '''2''' to the power of zero. # Continually repeat '''step #3''' moving leftwards, increasing the power of ''2'' by '''1''' (refer to diagram on right). # Add up the results to ~~Binary~~obtain the decimal value equivalent. * Binary '''NOTE:''' To convert ''octal'' and ''hexadecimal'' numbers to ~~Octal~~ '''decimal''', replace the number 2</ ~~Octal~~ span> (in red in the diagram to the right) with 8 (for ''octal'') or 16 (for ''hexadecimal''). ==== Method 2: Decimal to Binary ==== [[Image:decimal-to-bin.png|thumb|right|275px|Performing a '''decimal''' to '''binary''' conversion.]]When converting '''decimal''' numbers to '''binary''' numbers, perform the following steps: * Binary # Write down the '''decimal number''' to ~~Hexadecimal~~ be converted.# On the ''right-side'', write the number '''1''' and moving '''leftwards''', keep doubling</ ~~Hexadecimal~~ u> the numbers until that number is '''greater than''' the decimal number to ~~Binary~~be converted (refer to the diagram on the right). * Octal # Starting on the left-side of those doubled numbers, compare that number with the decimal number. If that number if less than or equal to the decimal number, then write a '''1''' below and subtract that number from the decimal number to ~~Hexadecimal / Hexadecimal~~ get a remainder. If the number is greater than decimal number (or remainder), then write a '''0''' below. # Repeat '''step #3''' (moving rightwards and comparing the number with the decimal's remainder) '''NOTE:''' If you are converting to ~~Octal~~'''8-bit''', '''32-bit''', etc., add '''leading zeros''' if necessary.

~~| style~~=~~"padding-left:15px;"|File Permissions~~* chmod=== <bru>* umaskMethod 3: Octal to Binary / Binary to Octal<~~br><br~~/u>====

|}''Binary to Octal''

~~===Why Study Data Representation?===~~# '''One octal number''' represents '''3 binary numbers''', so '''starting from right-side''', group binary digits into '''groups of 3''' (add leading zeros if necessary).# Write '''(4)(2)(1)''' under each '''group of 3 binary numbers'''.# Multiply the value or "placeholder" (i.e. '''0''''s and '''1''''s) by the corresponding '''(4)(2)(1)''' for each group to obtain the octal number (refer to diagram of ''binary to octal'' conversion).

''~~Data (treated as singular, plural, or as a mass noun) is any sequence of one or more symbols given meaning by specific act(s) of interpretation.Digital data is data that is represented using the binary number system of ones (1) and zeros (0), as opposed~~ Octal to ~~analog representation.~~Binary''~~ Reference: https://en.wikipedia.org/wiki/Data_(computing) ~~

~~Therefore~~# '''One octal number''' represents '''3 binary numbers''', ~~computers process and store information in~~ so space-out the octal numbers to make space for a binary number ~~system consisting of 0s and 1s~~.~~For many aspects~~ # Write '''(4)(2)(1)''' under each octal number.# Write '''0''''s or '''1''''s for each group of ~~programming and networking,~~ binary numbers to add up to the ~~details~~ corresponding octal number (refer to diagram of ~~data representation must be understood~~''octal to binary'' conversion).

~~'''For example~~==== Method 4:~~'''~~Hexadecimal to Binary / Binary to Hexadecimal ====

* C Programming<table align="right"><tr><td>[[Image: ~~Sending information over networks, files~~* Web Developmentbin-to-hex.png|thumb|right|275px|Performing a '''binary to hexadecimal''' conversion.]]</td><td>[[Image: ~~Setting color codes for webpage background or text~~ hex-to-bin.png|thumb|right|350px|Performing a '''hexadecimal to binary''' conversion.]]</td></tr></table>* Allowing or Limiting Unix / Linux File Access: Setting permissions for files and directories ''Binary to Hexadecimal''

# '''One hexadecimal number''' represents '''4 binary numbers''', so starting from right-side, group binary digits into '''groups of 4''' (add leading zeros if necessary).

# Write '''(8)(4)(2)(1)''' under each group of 4 binary numbers.

# Multiply the values or "placeholders" (i.e. '''0''''s and '''1''''s) by the corresponding (8)(4)(2)(1) for each group to obtain the octal number.

# Convert values from '''10''' to '''15''' to '''A''' to '''F''' (refer to diagram of ''binary to hexadecimal'' conversion)

~~In terms of this course, we will learn how a simple decimal number (integer) is stored into the computer system as a binary number.~~''Hexadecimal to Binary''

~~We will also learn other numbering systems~~ # '''One hexadecimal number''' represents '''4 binary numbers''', so space-out the hexadecimal numbers to make space for a binary number.# Convert letters '''A''' to '''F''' to '''10''' to 15 (~~octal and~~ refer to diagram of ''binary to hexadecimal'' conversion)# Write '''(8)(4)(2)(1) ~~that can be used as a "short-cut"~~ ''' under each hexadecimal number.# Write '''0''''s or '''1''''s for each group of binary numbers to add up to the corresponding hexadecimal number (refer to diagram of ''hexadecimal to ~~represent~~ binary ~~numbers~~'' conversion).

==== Method 5: Octal to Hexadecimal / Hexadecimal to Octal ====

~~ ~~[[Image:octal-hex.png|thumb|right|275px|For conversions between octal and hexadecimal numbers, use binary as a '''bridge'''.]]To convert using the method, simply use binary as a "'''bridge'''".

~~===Numbering Conversion===~~''Example:''

xTo convert octal to hexadecimal, convert octal to binary, then convert binary to hexadecimal.

To convert hexadecimal to octal, convert hexadecimal to binary, then convert binary to octal.

===File Permissions===

x[[Image:listing-file-directory.png|thumb|right|400px|Detailed directory listing showing permissions for a '''directory''' and a '''regular file'''.]]Since Unix / Linux operating file systems allow for '''multiple user accounts''' it is essential to have a system to '''share''' or '''limit''' access to directories and files contained within the file system. When '''directories''' and r'''egular files''' are created, they are assigned to an '''owner''' (typically the username which is the creator).To ''allow'' or ''limit'' '''access''' to those files and directories, those files and directories are assigned to an initial '''group''' referred to as a "'''primary group'''".[[Image:directory-permissions.png|thumb|right|350px|Permissions of a '''directory''' that contain subdirectories and regular files.]]Users that own those ''directories'' and ''regular files'' are referred to as '''users''', users that belong within the same group are referred to as '''same group members''', and those users that do NOT belong to a particular group are referred to as '''other group members'''. '''NOTE:''' In this course, we CANNOT create groups or assign users to groups in the '''Matrix''' server. Instead, you may learn how to those tasks when or if you take a Unix/Linux administration course. On the other hand, you can change which '''user''', '''same group members''' or '''other group members''' can access or NOT access a directory or regular file. [[Image:file-permissions.png|thumb|right|350px|Permissions of a '''regular file''' contained within a directory.]]File Permissions consist of '''two-layers''': '''First''', the permissions of a '''directory''' that contains regular files, and '''second''', permissions of the ''subdirectories and/or regular files'' within that directory. Permissions for directories have a different meaning than permissions for '''regular files'''. Refer to the diagrams to the right to see the explanation of permissions and how they differ between a directory and a regular file. A symbol ''dash'' "'''-'''" indicates that the permission has '''NOT''' been granted. The permissions of '''newly-created''' directories and regular files are automatically assigned via a '''user mask''' (we will discuss this shortly). In order to change permissions for directories and regular files, you would use the '''chmod''' command. '''Changing File Permissions with "chmod" command:'''[[Image:symbolic-chart.png|thumb|right|550px|Examples of adding, removing and setting permissions using the '''chmod''' command with the '''Symbolic''' method.]] '''Symbolic Method:''' The chmod can use '''symbols''' to ''add'', ''remove'', and ''set'' rwx permissions for the '''user''', '''same group members''', and/or o'''ther group members''' for a directory or reqular file. '''Octal (Absolute) Method:'''[[Image:octal-permissions.png|thumb|right|150px|Using octal numbers to represent setting file permissions.]]You can also use '''octal numbers''' to '''set''' permissions. This method is a short-cut and may require less typing than using the ''symbolic'' method. You can only use this method to set file permissions (as opposed to ''add'' or ''remove'' permissions. Since 1 octal digit represents 3 binary digits, one octal digit can represent the rwx permission granted or NOT granted. The permissions '''rwx''' are be in the form of 3 binary digits (1 represents the permission granted and 0 represents the permission NOT granted). '''NOTE:''' You can use the '''-R''' option to set permissions for directory, subdirectory and directory contents '''recursively'''. '''Setting Permissions for Newly-Created Directories and Regular Files (umask):''' <table align="right"><tr><td>[[Image:umask-directory.png|thumb|right|150px|Setting '''umask''' for newly-created '''directories'''.]]</td><td>[[Image:umask-file.png|thumb|right|150px|Setting '''umask''' for newly-created '''regular files''']]</td></tr></table>The '''umask''' command is used to set the permissions of newly-created directories and regular files.

Issuing the '''umask''' command without arguments will display the current umask value.

Refer to the diagrams on the right-side to set the umask value for directories and regular files.

Setting the umask value (for example umask 022) only takes effect for the current shell session unless the umask command is contained in a start-up file (e.g. '''.profile''', '''.bash_profile''', or '''.bashrc''').

=INVESTIGATION 1: NUMBERING CONVERSIONS=

'''ATTENTION''': This online tutorial will be required to be completed by '''Friday in week 5 by midnight''' to obtain a grade of '''2%''' towards this course

For this investigation, we will NOT be logged into our Matrix account, but it is recommended to have an '''MS Word document''' open to manually perform numbering conversions.

'''NOTE:''' It is essential that you learn how to manually perform numbering conversions since you will NOT be permitted to perform quizzes, midterm, or your final exam with a computer or a calculator. Learning to quickly perform manual numbering conversions will make IT professional more productive such as setting permissions, designing computer networks, or selecting complex colors when developing webpages.

[[Image:calc-check.png|thumb|right|200px|Only use a calculator to check your numbering conversion '''AFTER''' you have performed the operation '''manually'''. ]]

You will now get practice performing numbering conversions.

~~=INVESTIGATION 1: NUMBERING CONVERSIONS=~~

'''Perform the Following Steps:'''

x# Let's convert the following binary number '''10111110''' to a '''decimal number'''. '''NOTE:''' It is important to learn and '''memorize''' the '''correct methods''' to perform the proper numbering conversion method (i.e. view '''method 1''' above (drawing the L's). # Write the manual conversion either in your MS Word document. # Use a '''calculator''' to check your work. In MS Windows, you can set the calculator to Programming mode by making the selection to '''binary''', enter the binary number '''10111110''' and view the decimal equivalent. Did you get the correct answer? If not, retry the method and check to see what you did wrong. # Perform a manual conversion of the '''decimal number 55''' to a '''binary number'''. What method (displayed above) will you use? Use a calculator to check your work. # Perform a manual conversion of the '''octal number 461''' to a '''binary number'''. What method (displayed above) will you use? Use a calculator to check your work. # Perform a manual conversion of the '''binary number 11110001''' to a '''hexadecimal number'''. What method (displayed above) will you use? Use a calculator to check your work. # Perform a manual conversion of the '''hexadecimal number ABC''' to a '''binary number'''. What method (displayed above) will you use? Use a calculator to check your work. # Perform a manual conversion of the '''binary number 10101111''' to an '''octal number'''. What method (displayed above) will you use? Use a calculator to check your work. # Perform a manual conversion of the same '''binary number 10101111''' to a '''hexadecimal number'''. What method (displayed above) will you use? Use a calculator to check your work. # Perform a manual conversion of the '''octal number 5636''' to a '''hexadecimal number'''. What method (displayed above) will you use? Use a calculator to check your work. # Perform a manual conversion of the '''hexadecimal number D68''' to an '''octal number'''. What method (displayed above) will you use? Use a calculator to check your work. # When you have performed all of the numbering conversions above, then you can proceed to the next INVESTIGATION.

=INVESTIGATION 2: FILE PERMISSIONS=

[[Image:file-permission-practice-1.png|right|250px|thumb|]]

In this investigation, you will get experience using the '''chmod''' command to '''change permissions''' for existing files and the using '''umask''' command to automatically set permissions for newly-created files.

'''Perform the Following Steps:'''

# '''Login''' to your matrix account and issue a command to '''confirm''' you are located in your '''home''' directory.

# Issue a single Linux command to create the following directory structure displayed in the diagram to the right. '''NOTE:''' You will now run a shell script to confirm that you properly created that directory structure in your ''Matrix'' account.

# Issue the following Linux command to run a checking script: ~uli101/week4-check-1

# If you encounter errors, make corrections and '''re-run''' the checking script until you receive a congratulations message, then you can proceed. [[Image:file-permission-practice-2.png|right|450px|thumb|]]

# Issue Linux commands to create '''empty files''' for each of those newly created '''directories''' as shown in diagram to the right: '''NOTE:''' You will now run another shell script to confirm that you properly created those empty files within those specified directories.

# Issue the following Linux command to run a checking script: ~uli101/week4-check-2

# If you encounter errors, make corrections and '''re-run''' the checking script until you receive a congratulations message, then continue the remaining steps. Let's get practice '''viewing permissions''', '''changing permissions''', and automatically '''setting permissions for newly created files'''.

# Issue the following Linux commands: ls -ld ~/documents ~/clients ~/vendors ls -lR ~/documents ~/clients ~/vendors '''NOTE:''' You should see permissions already set for those newly created directories and regular files. What do these permissions mean for '''same group member''' and '''other group member''' access to those directory and regular files?

# Let's limit access to the '''clients''' and '''vendors''' directories to only yourself and same group members. Issue the following Linux command: chmod 750 ~/clients ~/vendors

# Issue the '''ls -ld''' and '''ls -lR''' commands (as you did in ''step #8'') to confirm that the permissions for those directories have been changed. '''NOTE:''' The '''-R''' option for the '''chmod''' command can change the file permissions recursively within a directory structure.

# Issue the following Linux command: chmod 750 -R ~/documents

# Issue the '''ls -ld''' command to confirm the permissions for the '''~/documents''', '''~/document/memos''' , '''~/documents/reports''', and '''~/documents/contracts''' directories.

# Issue the following Linux command: ls -lR ~/documents What do you noticed happened to the permissions for the regular files contained in those directories. Did those regular file permissions change? We will now change permissions for regular text file contained in subdirectories of the '''documents''' directory to: r w - r - - - - -

# Issue the following Linux commands: chmod 640 ~/documents/memos/memo*.txt chmod 640 ~/documents/reports/report*.txt chmod 640 ~/documents/contracts/contract*.txt

# Issue the ls -lR command for the '''~/documents''' directory to confirm that those regular file permission have changed. Let's run a checking script to make certain you correctly set permissions for those directories and files.

# Issue the following: ~uli101/week4-check-3

# If you encounter errors, make corrections and then re-run the checking script until you receive a congratulations message and then continue with this tutorial. Let's get some practice setting permissions to allow users to make editing changes to regular files.

# Issue the following Linux command: chmod ugo-w ~/documents/memos/memo*.txt

# Use the ls command to verify that those regular file's permissions have changed.

# Using the nano or vi text editor, open the regular file '''~/documents/memos/memo1.txt''' and type in some text and try to save your editing changes. What happened?

# To '''abort''' your editing session in '''vi''': type :q! and press '''ENTER'''. To '''abort''' your editing changes in '''nano''': type ctrl-x type n and then press '''ENTER''' when prompted to save editing changes.

# Issue the following Linux command to add write permissions for all files in the '''memos''' directory for yourself (i.e. user): chmod u+w ~/documents/memos/*

# Repeat steps to edit the file '''~/documents/memos/memo1.txt''' (as you did in ''step #20''). Were you able to edit the file and save your editing changes?

# Issue a Linux command to view the contents of the '''~/documents/memos/memo1.txt''' text file that you were able to edit.

# Issue the following Linux command to view permissions for your '''home''' directory: ls -ld ~ What does execute permissions mean for same group members and other group members in terms of your '''home''' directory?

# Issue the following Linux command to create a new subdirectory: mkdir ~/shared

# Issue the following Linux command: ls -ld ~/shared What are the permissions for this newly-created directory? Can other users access the directory pathname '''~youruserid/shared''' ?

# Issue the following Linux command (without an argument): umask '''NOTE:''' You should see a '''four-digit octal''' number. Drop the leading zero on the left to obtain the '''default umask value'''.

# Perform a '''mathematical calculation''' by taking the octal number '''777''' and subtracting the default umask value you determined in the previous step. What is the result?

# Convert that octal number result to a '''binary''' number. What does that represent as newly created directory permissions? Does that correspond to the permissions for the newly created '''~/shared''' directory?

# Repeat the calculation (like in step #28) but with a umask setting of '''077''' to see how this new umask setting would affect permissions of newly-created directories.

# Issue the following Linux command: umask 077

# Issue the following Linux command (without arguments): umask NOTE: You should notice the value '''0077'''. By dropping the leading zero to the left, that would provide the default '''umask value of 077'''.

# Issue the following Linux command: mkdir ~/shared2

# Issue the following Linux command: ls -ld ~/shared2 Do the permissions for this newly created directory match the predicted permissions that you calculated in '''step #30'''?

# Issue the following Linux command to create an empty regular file called '''myfile.txt''' in the '''~/shared2''' directory: touch ~/shared2/myfile.txt

# Use the ls -l command to view the permissions for this newly created regular file. What do you notice about those permissions? Let's run a checking script to make certain you correctly set permissions for those recently-created directories and files.

# Issue the following: ~uli101/week4-check-4 If you encounter errors, make corrections and then re-run the checking script until you receive a congratulations message and then continue with this tutorial.

# Logout of your Matrix account, and then log-back into your Matrix account.

# Issue the following Linux command (without arguments): umask What happened? Referring to your notes, what do you need to do to make that umask value persistent? '''WARNING''': You should be extremely aware of your permissions since you may perform '''marked work''' for other courses on your '''Matrix''' server. You should NOT set permissions to share your work with '''same group''' or '''other group''' members (unless given '''specific permissions instructions from your course professors'''). If students can have access to your directories and project files, they could '''copy''' your work and thus make yourself and other student(s) that copied your work to be charged with '''academic dishonesty'''.

: Complete the Review Questions sections to get additional practice.

= LINUX PRACTICE QUESTIONS =

The purpose of this section is to obtain extra practice to help with your quizzes, your midterm, and your final exam.

Here is a link to the MS Word Document of ALL of the questions displayed below but with extra room to answer on the document to

simulate a quiz:

https://wiki.cdot.senecacollege.ca/uli101/files/uli101_week4_practice.docx

Your instructor may take-up these questions during class. It is up to the student to attend classes in order to obtain the answers to the following questions. Your instructor will NOT provide these answers in any other form (eg. e-mail, etc).

'''Review Questions:'''

# List the number of digits for the following numbering systems:<ul><li>'''Decimal'''</li><li>'''Binary'''</li><li>'''Octal'''</li><li>'''Hexadecimal'''</li></ul>

# Write a simple chart to show which values are represented for letter '''A - F''' for a hexadecimal number.

# How many '''binary''' digits does 1 octal digit represent?

# How many '''binary''' digits does 1 hexadecimal digit represent?[[Image:number-conversion-chart.png|right|450px|thumb|]]

# Use '''manual numbering conversion''' to complete the table displayed to the right.

<ol><li value="6">Write the '''chmod''' command (using the ''symbolic'' method) to set “'''pass-through'''” permissions (eg. r w x - - x - - x) for your '''home''' directory using an '''absolute pathname'''. Write a Linux command to verify that permissions where set. </li><li>Perform a binary to octal numbering conversion for the permissions: '''r w x - - x - - x''' Write single Linux command to set “'''pass-through'''” permissions for your '''home''' directory, using the '''absolute method''' (i.e. octal numbers). </li><li>Write a single Linux command to '''add read permissions''' for '''same group members''' for the '''~/tests''' directory. </li><li>Write a single Linux command to '''remove write permissions''' for '''same group members''' and '''other group members''' for the '''~/projects''' directory. Use the ''symbolic'' method. </li><li>Write a single Linux command to set the permissions for the '''~/assignments''' directory to the following using the '''absolute''' method (i.e. octal numbers): '''r w x r - x - - x''' Show your work to perform a '''binary''' to '''octal''' conversion. Write the command below using octal numbers and using a relative-to-home pathname. </li><li>Assume that you just issued the command:

chmod u=rwx,go=x ~/linux/content What would be the new permissions for the “'''content'''” directory? </li><li>Assume that you just issued the commands: umask 077 mkdir mydir touch mydir/myfile.txt What would be the permissions for the newly created '''directory''' and '''regular file'''? (show your work)

</li></ol>

_________________________________________________________________________________

Author: Murray Saul

License: LGPL version 3

Link: https://www.gnu.org/licenses/lgpl.html

_________________________________________________________________________________

x.[[Category:ULI101]]

Andrew

Bureaucrats, Administrators

1,234

edits

CDOT Wiki β

Changes

Tutorial4: Data Representation / Numbering Conversion / File Permissions

CDOT Wiki ^β