Difference between revisions of "Tutorial9: Regular Expressions"

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===Linux Commands that Use Regular Expressions===
 
===Linux Commands that Use Regular Expressions===
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=INVESTIGATION 1: SIMPLE & COMPLEX REGULAR EXPRESSIONS=
 
=INVESTIGATION 1: SIMPLE & COMPLEX REGULAR EXPRESSIONS=

Revision as of 09:49, 4 July 2020

USING REGULAR EXPRESSIONS


Main Objectives of this Practice Tutorial

  • Explain the purpose of Regular Expressions
  • Understand the difference between Regular Expressions and Filename Expansion
  • Understand the purpose of Literal (Simple) Regular Expressions
  • Understand common symbols for Complex Regular Expressions and their purpose
  • Understand command symbols for Extended Regular Expressions and their purpose
  • Use various Linux commands that use regular expressions

Tutorial Reference Material

Course Notes
Linux Command/Shortcut Reference
YouTube Videos
Course Notes:


Regular Expressions
  • Simple
  • Complex
  • Extended


Additional Linux Commands that Use Regular Expressions Brauer Instructional Videos:

KEY CONCEPTS

regular expression … is a sequence of characters that define a search pattern.

Usually such patterns are used by string searching algorithms for "find" or "find and replace" operations on strings, or for input validation.
Reference: https://en.wikipedia.org/wiki/Regular_expression

Regular Expressions vs. Filename Expansion

Filename expansion symbols allow the Linux shell to expand filenames as arguments (referred to as “globbing”).
Output of the ls -lR command to display directory structure.
In a previous lesson, you learned that filename expansion symbols allow the Linux shell to expand filenames as arguments (referred to as “globbing”) for file management commands. This is very useful for managing multiple files sharing similar characteristics such as the same file extension.

Filename Expansion symbols are used to search, edit and manipulate text and are used with Linux file management commands such as ls, rm, mv, cp, cat, less and more. This can represent text contained in files or text as a result of issuing Linux commands using a pipeline.

regular expression is a combination of two types of characters: literals and special characters.
In combination, these characters define a logical pattern. Strings of text can be compared to this pattern
to see if they fit the pattern defined by the expression.

Reference: https://www.whoishostingthis.com/resources/regex/

Literal (Simple) Regular Expressions

The simplest regular expression is a series of letters and numbers, possibly including white space (tabs or space characters), that have no special meaning. Such a regular expression consists of ``literals; that is, normal letters, which match only an identical letter in the data being searched.

For example:
"This is a regular expression"

When an editor searches for a literal regular expression, it can only score a ``hit if it finds exactly that sequence of characters in the data it is searching. 
Reference: http://osr507doc.xinuos.com/en/OSUserG/_Literal_chars_in_regexps.html

Complex Regular Expressions

x


Extended Regular Expressions

x


Linux Commands that Use Regular Expressions

x

INVESTIGATION 1: SIMPLE & COMPLEX REGULAR EXPRESSIONS


In this section, you will learn how to ...



Perform the Following Steps:

  1. x

In the next investigation, you will ...

INVESTIGATION 2: EXTENDED REGULAR EXPRESSIONS

In this section, you will learn how to ...


Perform the Following Steps:

  1. x

In the next investigation, you will ...

INVESTIGATION 3: OTHER COMMANDS THAT USE REGULAR EXPRESSIONS

In this section, you will learn how to ...


Perform the Following Steps:

  1. x

LINUX PRACTICE QUESTIONS

The purpose of this section is to obtain extra practice to help with 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://ict.senecacollege.ca/~murray.saul/uli101/uli101_week9_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