Tutorial3: Advanced File Management / Quoting Special Characters

ADVANCED UNIX / LINUX FILE MANAGEMENT

Main Objectives of this Practice Tutorial

• Understand the difference between absolute / relative / relative-to-home pathnames

• Become productive using various pathname types for Unix/Linux File Management

• Understand the following Ambiguous Filename expansion (FNE) Symbols: * / ? / [ ] / [! ]

• Become productive using FNE for Unix/Linux File Management

• Understanding quotation symbols: Backslash \ , single quotes ' ' , double quotes " "

• Understand the purpose of quoting special characters for File Management and issuing Linux commands

Tutorial Reference Material

Course Notes	Pathname Type / Filename Expansion / Quoting Reference		YouTube Videos
Course Notes: PDF | PPTX	Pathname Types Absolute Relative Relative-to-home Ambiguous Filename Expansion Symbols Asterisk * , Question ? , Character Class [ ] and [! ]	Quotation Symbols Backslash \ , Single ' ' , Double " "	Instructional Videos: Using Pathname Types Filename Expansion Quoting Special Characters

Pathname Types

A pathname is a fully-specified location of a unique filename within the file system.

The concept of a pathname relates to every operating system including Unix, Linux, MS-DOS, MS-Windows, Apple-Macintosh, etc.

It is important to understand file pathnames since you need to save or access a file without ambiguity because there may be several files by that name in various directories.

For example: Accessing the cars.txt file - which file to access? It depends on the location of the file

/home/userid/uli101/cars.txt
/public/uli101/samples/cars.txt
/etc/data/cars.txt

Absolute Pathnames

Directories in red display the FULL path from the root directory to the bin directory (i.e. the absolute pathname: /bin.

Directories in red display the FULL path from the root directory to the examples directory (i.e. the absolute pathname: /home/userid/uli101/examples.

An absolute pathname is a path to the file or directory always beginning from the root directory (i.e. / ).

This type of pathname is referred to as absolute because the pathname always begins from the root directory, regardless the location or your current directory. In other words, this type of pathname requires that you always provide the FULL pathname starting with the root directory.

Advantages of using Absolute Pathnames:

• Useful if you do not know your current directory location
• Easier to understand the FULL layout of pathname

Example:
mkdir /home/userid/uli101 will create the uli101 directory in the home directory of the user called: userid. This command is using an absolute pathname.

Relative Pathnames

Directories in red display the path from the current directory location (which is xyz100) to the bin directory (i.e. the relative pathname: ../../../bin.

Directories in red display the path from the current directory location (which is uli101) to the examples directory (i.e. the relative pathname: uli101/examples or ./uli101/examples

A relative pathname is a path to a file or directory that begins from your current directory. This is called relative because it is used to locate a specific file relative to your current directory.

NOTE: In order to use relative pathnames, it is absolutely necessary that you know the location of your current directory!

Relative Pathname Symbols:

. A period symbol "." represents the current directory

.. Two consecutive period symbols ".." represents the parent directory (one level up)

Advantages of using Relative Pathnames:

• Possible shorter pathname (less typing)

For example: mkdir uli101 or mkdir ./uli101 will create the uli101 directory in your current directory.

Relative-to-home Pathnames

Directories in red display the path from the home directory of the current user (which is userid) to the examples directory (i.e. the relative-to-home pathname: ~/uli101/examples.

Directories in red display the path from the current directory location (which is uli101) to the examples directory (i.e. the relative pathname: uli101/examples or ./uli101/examples

You can specify a pathname as relative-to-home by using a tilde and slash at the start, e.g. ~/uli101/notes.html

The tilde character ~' is replaced by your home directory (typically /home/current-user-id)

You can immediately place a username after the tilde to represent another user’s home directory. For example: ~jane = /home/jane

Advantages of using Relative-to-home Pathnames:

• Possible shorter pathname

Examples:

mkdir ~uli101 will create the uli101 directory in current user's home directory.
ls ~jane will display contents of jane's home directory (/home/jane).

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

Ambiguous Filename Expansion

x

Quoting Special Characters

x

INVESTIGATION 1: ABSOLUTE / RELATIVE / RELATIVE-TO-HOME PATHNAMES

The best way to learn about pathname types is to issue many Linux file management commands using each type (absolute, relative, relative-to-home) and see which ones (or combination) is the most efficient (requiring the least number of keystrokes).

Perform the Following Steps:

1. Login your matrix account.
   
   
2. Issue a command to confirm you are located in your home directory.
   
   Let's create the following directory structure under your home directory by issuing the mkdir command using only absolute pathnames.
   
   NOTE: The command you issue below will be VERY LONG... just keep typing and let the text continue of separate lines. When using these absolute pathnames, start each one from the root directory (/) and replace the text "youruserid" with your actual login id.
   
   
3. Issue the following Linux command to create the directory structure displayed to the right using all absolute pathnames:
   
   mkdir -p /home/youruserid/tutorial3/practice/commands /home/youruserid/tutorial3/practice/examples /home/youruserid/tutorial3/notes/lesson1 /home/youruserid/tutorial3/notes/lesson2
   
   

INVESTIGATION 2: FILENAME EXPANSION

x

Perform the following steps:

1. X

INVESTIGATION 3: QUOTING SPECIAL CHARACTERS

x

Perform the Following Steps:

1. X

LINUX PRACTICE QUESTIONS

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

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://ict.senecacollege.ca/~murray.saul/uli101/uli101_week3_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:

1. X
2. X
3. X
4. X
5. X
6. X
7. X
8. X