Linux-New/C3/Mastering-grep/English - Revision history

Madhurig: Madhurig moved page Linux-Ubuntu/C3/Mastering-grep/English to Linux-New/C3/Mastering-grep/English

2026-03-24T11:11:55Z

Madhurig moved page Linux-Ubuntu/C3/Mastering-grep/English to Linux-New/C3/Mastering-grep/English

Madhurig at 06:26, 13 March 2026

2026-03-13T06:26:54Z

Madhurig at 12:43, 12 March 2026

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Madhurig at 13:55, 11 March 2026

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Madhurig at 12:42, 11 March 2026

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Ketkinaina: Created page with "'''TITLE: Mastering Grep''' '''Author:''' EduPyramids''' '''Keywords:''' grep, search, pattern matching, regular expressions, extended regex, case-insensitive search, cha..."

2026-01-26T11:40:23Z

Created page with "'''TITLE: Mastering Grep''' '''Author:''' EduPyramids''' '''Keywords:''' grep, search, pattern matching, regular expressions, extended regex, case-insensitive search, cha..."

New page

'''TITLE: Mastering Grep'''

'''Author:''' EduPyramids'''

'''Keywords:''' grep, search, pattern matching, regular expressions, extended regex, case-insensitive search, character classes, anchors, dot operator, asterisk operator, Linux, Ubuntu, Bash, text search, EduPyramids, video tutorial.

{| border=1
|| '''Visual Cue'''
|| '''Narration'''
|-
|| Slide 1

'''Title Slide'''

|| Welcome to this spoken tutorial on '''Mastering grep'''.
|-
|| '''Slide 2 '''
Learning Objectives'''

In this tutorial, we will learn to:
* Match more than one pattern
* Check a word that has a different spelling
* Character classes
* Use of '''*''' operators
* Match any one character using dot
* Match a pattern at the beginning and ending of a line.
|| In this tutorial, we will learn to:
* Match more than one pattern.
* Check a word that has a different spelling.
* Character classes.
* Use of '''asterisk''' operators.
* Match any one character using a dot.
* Match a pattern at the beginning and ending of a line

|-
|| '''Slide 3'''

'''System Requirements'''

|| To record this tutorial, I am using:

'''Ubuntu OS '''version 24 point zero 4.
|-
|| '''Slide 4'''

'''Pre-requisites'''

[https://edupyramids.org/ https://EduPyramids.org]

|| To follow this tutorial,

Learners should have '''Ubuntu '''version 24 point zero 4.

And should be familiar with basic Linux terminal commands.

For the prerequisite Linux tutorials please visit this website.
|-
|| '''Slide 5'''

'''Code files'''

'''grepdemo.txt'''

'''grep-commands.txt'''
|| The following code files are required to practice this tutorial.

These files are provided in the Code Files link of this tutorial page.

|-
||
|| Let us get started with grep commands.
|-
|| '''Note: Please type the commands on the terminal don't paste as the double quotes are wrong.'''

Type '''grep -e "electronics” -e "civil" grepdemo.txt '''Press '''Enter'''.
|| Let us get the details of students from the Civil or Electronics stream.

We will use the same example file, '''grep demo dot t x t'''.

We can match multiple patterns using the '''hyphen e''' option in '''grep'''.

Type this command and press '''Enter'''.

Output displays both the civil and electronics students records.
|-
|| Type '''grep -ie “choudhury” -ie “chowdhari” grepdemo.txt '''Press '''Enter'''

Type''' clear and press Enter.'''
|| Now we wish to search for people whose title is Choudhury.

The issue is that the title may be spelled in different ways.

How can we handle this?

In such cases, we can perform a case-insensitive search using the '''hyphen i '''option.

We can as well combine it with multiple '''hyphen e''' options.

This helps to match different spellings of the same word. Type this command and press''' Enter.'''

The output is displayed. However, there can be many other ways to write the name.

We could use many -e options, but a better solution is Regular Expressions.

Let me clear the screen.
|-
||
|| There are several special characters used in regular expressions.
|-
|| '''Slide 6'''

'''charcter-class.png'''

'''Character class'''

|| A character class is a part of a regular expression.

It allows us to define a group of characters inside square brackets.

When a pattern is matched, only one character from this group is selected.

For example, square bracket '''a b c '''matches either '''a''', '''b''', or '''c'''.

The pattern square bracket zero to nine matches any one digit from zero to nine.

Square bracket a to z matches any one lowercase letter.

Character classes are useful when more than one character is allowed.

To specify a larger range, we use the format: first character hyphen last character.

For example, [0-9] matches any digit.

Only one character from the range is matched at a time.
|-
||
|| Let us look at some examples.
|-
|| In terminal type '''grep -i “ch[ao][uw]dh[ua]r[yi]”'''

'''grepdemo.txt'''

Press '''Enter Add annotation for this'''
|| To understand character class type this command and press '''Enter'''.

Observe the output.

This matches most variations of the name chowdhury spelt differently.

However, it still does not match '''choudhuree''' with double '''e'''.
|-
|| '''Slide 7'''

'''The asterisk (*) operator'''

The '''* operator''' is a regular expression operator.

It matches zero or more repetitions of the preceding character or pattern.

This allows us to match repeated characters, or even when the character is absent.

For example, ab* matches a, ab, abb, abbb, and so on.
|| The asterisk operator is a regular expression operator.

It matches zero or more repetitions of the preceding character or pattern.

This allows matching repeated characters or cases where the character is absent.

For example, the pattern ab asterisk (*) matches a, ab, abb, abbb, and so on.

|-
|| Type:

'''grep -i “m[ei]*ra*” grepdemo.txt''' press '''Enter'''

|| Let us match a student's name Mira in the file.

Type this command and press '''Enter''' to see the output.

We see records of Mira with 3 different spellings here.
|-
|| '''Slide 8'''

'''The Dot Operator'''

In regular expressions, the '''dot (.) operator''' is a special character.

It matches '''any single character''', except the newline character.

For example:* a.c matches abc, a1c, or a_c
* It does not match '''ac''' because one character is required between''' a''' and '''c'''

The '''dot operator''' is used when the character is unknown but its position is fixed.
|| The '''dot''' is a special character in regular expressions.

It matches any single character, except the newline character.

For example, the pattern '''a dot c '''can match '''a b c''', '''a 1 c''', or '''a underscore c'''.

However, it will not match '''a c''', because one character must appear between '''a''' and '''c'''.

The '''dot operator''' is used when the character is unknown but its position is fixed.
|-
|| Type '''grep "M… " grepdemo.txt'''

press '''Enter'''
|| For example, type this command and press '''Enter'''.

It searches for four letter words that start with '''M'''.

Each dot matches one character.

The space after the dots ensures only four-letter matches.

This avoids matching words longer than four letters.

The output shows records for students '''Mani''' and '''Mira'''.
|-
|| '''Slide 9'''

'''Anchors (^ and $)'''

An '''anchor''' is a special symbol in regular expressions.

It specifies where a pattern should match in a line.

It does not match any character, it matches only a position.

The two most common anchors are''' ^ '''and '''$'''.

To match a pattern at the beginning of a line, we use the caret ^ symbol.

To match a pattern at the end of a line, we use the dollar sign '''$'''.
|| An anchor is a special symbol used in regular expressions.

It specifies where a pattern should match in a line.

Anchors do not match any character, they match only a position.

The two most common anchors are the '''caret''' and the '''dollar''' sign. We use '''caret''' to match a pattern at the beginning of a line.

We use dollar to match a pattern at the end of a line.
|-
|| At the prompt type '''grep "^A" grepdemo.txt'''

press '''Enter'''

Point to the output.
|| Let us use anchors.

Now, we will extract entries with roll numbers starting with A.

The roll number is the first field in the file.

Type this command and press '''Enter'''.

Only lines with roll numbers starting with A are shown.

The '''caret''' acts as an anchor for the beginning of the line.

Grep matches lines where the first character is '''A'''.

All other lines, starting with different characters, are ignored.
|-
|| Add annotation.Press '''Ctrl''' and '''L''' keys together to clear the screen.
|| Let me clear the screen
|-
|| Type: '''grep "1$" grepdemo.txt'''Press '''Enter'''.

Type: '''grep "[78]...$" grepdemo.txt'''

press '''Enter'''
|| Let us match a pattern at the end of the file.

To match a pattern at the end of a line, we use the dollar sign.

Here is the output.

To find stipends between 7000''' '''to 8999'''. '''Type this command and press '''Enter'''.

Only lines with stipend numbers ending in the specified digit are shown.

That is, the numbers between 7000 and 8999.

Here, it searches for 7 or 8 first.

Then any 3 characters following it, from the end of the file '''grep demo dot t x t'''.
|-
|| '''Slide 10'''

'''Summary'''

In this tutorial, we have learnt to:
* Match more than one pattern
* Check a word that has a different spelling
* Character classes
* Use of '''*''' operators
* Match any one character using dot
* Match a pattern at the beginning and ending of a line.

|| With this we come to the end of this tutorial.

Let us summarise.
|-
|| '''Slide 11'''

'''Assignment'''

As an assignment# Search for students whose names contain the letters “ra” in sequence.
# Find entries where the stream is either “Mechanical” or “Electrical.”
# List all students whose roll numbers end with the digit 5.
# Count how many students have a stipend greater than 5000.

|| As an assignment, please do the following.
|-
|| '''Slide 12'''

'''Thank you'''
|| This Spoken Tutorial is brought to you by EduPyramids educational services private limited SINE IIT Bombay. Thank you.
|-
|}

← Older revision	Revision as of 11:11, 24 March 2026
(No difference)

@@ Line 77: / Line 77: @@
 Type '''grep -e "electronics” -e "civil" grepdemo.txt '''Press '''Enter'''.
-|| Let us get the details of students from the Civil or Electronics stream.
+|| We can match multiple patterns using the '''hyphen e''' option in '''grep'''.
 We will use the same example file, '''grep demo dot t x t'''.
-We can match multiple patterns using the '''hyphen e''' option in '''grep'''.
+Let us get the details of students from the Civil or Electronics stream.
 Type this command and press '''Enter'''.
@@ Line 100: / Line 102: @@
 We can as well combine it with multiple '''hyphen e''' options.
-This helps to match different spellings of the same word. Type this command and press''' Enter.'''
+This helps to match different spellings of the same word.
 The output is displayed.
@@ Line 145: / Line 149: @@
 It matches zero or more repetitions of the preceding character or pattern.
-and press '''Enter''' to see the output.
+Press '''Enter''' to see the output.
 We see records of Mira with 3 different spellings here.
@@ Line 160: / Line 164: @@
-press '''Enter'''.
+Now press '''Enter'''.
 It searches for four letter words that start with '''M'''.
@@ Line 203: / Line 207: @@
 All other lines, starting with different characters, are ignored.
 |-
-|| Add annotation.Press '''Ctrl''' and '''L''' keys together to clear the screen.
-|| Let me clear the screen
-|-
 || Type: '''grep "1$" grepdemo.txt'''Press '''Enter'''.
@@ Line 217: / Line 219: @@
 Here is the output.
-To find stipends between 7000''' '''to 8999'''. '''Type this command and press '''Enter'''.
+To find stipends between 7000 to 8999.
 Only lines with stipend numbers ending in the specified digit are shown.
 That is, the numbers between 7000 and 8999.
 Here, it searches for 7 or 8 first.

@@ Line 132: / Line 132: @@
 However, it still does not match '''choudhuree''' with double '''e'''.
 |-
-−
-−
-−
 || Type:
@@ Line 174: / Line 172: @@
 The output shows records for students '''Mani''' and '''Mira'''.
 |-
 || At the prompt type '''grep "^A" grepdemo.txt'''
@@ Line 230: / Line 227: @@
 Then any 3 characters following it, from the end of the file '''grep demo dot t x t'''.
 |-
-|| '''Slide 10'''
+|| '''Slide 6'''
 '''Summary'''
@@ Line 246: / Line 243: @@
 Let us summarise.
 |-
-|| '''Slide 11'''
+|| '''Slide 7'''
 '''Assignment'''
-As an assignment# Search for students whose names contain the letters “ra” in sequence.
+As an assignment
 # Find entries where the stream is either “Mechanical” or “Electrical.”
 # List all students whose roll numbers end with the digit 5.
@@ Line 257: / Line 255: @@
 || As an assignment, please do the following.
 |-
-|| '''Slide 12'''
+|| '''Slide 8'''
 '''Thank you'''

@@ Line 174: / Line 174: @@
 The output shows records for students '''Mani''' and '''Mira'''.
 |-
-An '''anchor''' is a special symbol in regular expressions.
+|| At the prompt type '''grep "^A" grepdemo.txt'''
-It specifies where a pattern should match in a line.
+press '''Enter'''
-It does not match any character, it matches only a position.
+Point to the output.
-The two most common anchors are''' ^ '''and '''$'''.
+Now, we will extract entries with roll numbers starting with A.
-To match a pattern at the beginning of a line, we use the caret ^ symbol.
+The roll number is the first field in the file.
-To match a pattern at the end of a line, we use the dollar sign '''$'''.
+Type this command
-|| An anchor is a special symbol used in regular expressions.
 It specifies where a pattern should match in a line.
@@ Line 195: / Line 195: @@
 Anchors do not match any character, they match only a position.
-Type this command and press '''Enter'''.
+Now press '''Enter'''.
 Only lines with roll numbers starting with A are shown.
@@ Line 274: / Line 260: @@
 '''Thank you'''
-|| This Spoken Tutorial is brought to you by EduPyramids educational services private limited SINE IIT Bombay. Thank you.
 |-
 |}

@@ Line 4: / Line 4: @@
 '''Keywords:''' grep, search, pattern matching, regular expressions, extended regex, case-insensitive search, character classes, anchors, dot operator, asterisk operator, Linux, Ubuntu, Bash, text search, EduPyramids, video tutorial.
@@ Line 27: / Line 26: @@
 * Match any one character using dot
 * Match a pattern at the beginning and ending of a line.
 || In this tutorial, we will learn to:
 * Match more than one pattern.
@@ Line 102: / Line 102: @@
 This helps to match different spellings of the same word. Type this command and press''' Enter.'''
-The output is displayed. However, there can be many other ways to write the name.
+The output is displayed.
 We could use many -e options, but a better solution is Regular Expressions.
@@ Line 111: / Line 113: @@
 || There are several special characters used in regular expressions.
 |-
 ||
 || Let us look at some examples.
@@ Line 145: / Line 122: @@
 Press '''Enter Add annotation for this'''
-|| To understand character class type this command and press '''Enter'''.
+|| A character class is a part of a regular expression.
 Observe the output.
@@ Line 153: / Line 132: @@
 However, it still does not match '''choudhuree''' with double '''e'''.
 |-
-The '''* operator''' is a regular expression operator.
-−
-It matches zero or more repetitions of the preceding character or pattern.
-−
-This allows us to match repeated characters, or even when the character is absent.
-−
-For example, ab* matches a, ab, abb, abbb, and so on.
-|| The asterisk operator is a regular expression operator.
-−
-It matches zero or more repetitions of the preceding character or pattern.
-−
-This allows matching repeated characters or cases where the character is absent.
-−
-For example, the pattern ab asterisk (*) matches a, ab, abb, abbb, and so on.
-−
-|-
 || Type:
@@ Line 179: / Line 141: @@
 || Let us match a student's name Mira in the file.
-Type this command and press '''Enter''' to see the output.
+Type this command
-We see records of Mira with 3 different spellings here.
+The asterisk operator is a regular expression operator.
-|-
-|| '''Slide 8'''
-'''The Dot Operator'''
+It matches zero or more repetitions of the preceding character or pattern.
-In regular expressions, the '''dot (.) operator''' is a special character.
+and press '''Enter''' to see the output.
-It matches '''any single character''', except the newline character.
+We see records of Mira with 3 different spellings here.
-For example:* a.c matches abc, a1c, or a_c
+press '''Enter'''
-* It does not match '''ac''' because one character is required between''' a''' and '''c'''
+|| For example, type this command
 The dot is a special character in regular expressions.
-The '''dot operator''' is used when the character is unknown but its position is fixed.
-|| The '''dot''' is a special character in regular expressions.
 It matches any single character, except the newline character.
-However, it will not match '''a c''', because one character must appear between '''a''' and '''c'''.
+press '''Enter'''.
-−
-The '''dot operator''' is used when the character is unknown but its position is fixed.
-|-
-|| Type '''grep "M… " grepdemo.txt'''
-−
-press '''Enter'''
-|| For example, type this command and press '''Enter'''.
 It searches for four letter words that start with '''M'''.