PoojaMoolya: Created page with "Sachin p: review done'''Title of script''': sed - The stream editor '''Author: Sachin Patil and Anirban''' '''Keywords: stream, editor, display, substitute, insert, delete'..."

2015-01-29T07:20:48Z

Created page with "Sachin p: review done'''Title of script''': sed - The stream editor '''Author: Sachin Patil and Anirban''' '''Keywords: stream, editor, display, substitute, insert, delete'..."

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Sachin p:

review done'''Title of script''': sed - The stream editor

'''Author: Sachin Patil and Anirban'''

'''Keywords: stream, editor, display, substitute, insert, delete'''

{| style="border-spacing:0;"
| style="border:1pt solid #000000;padding:0.097cm;"| <center>'''Visual Cue'''</center>
| style="border:1pt solid #000000;padding:0.097cm;"| <center>'''Narration'''</center>

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display slide 1
| style="border:1pt solid #000000;padding:0.097cm;"| Welcome to this spoken tutorial on the sed - the stream editor.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display slide 2

Learning objectives
| style="border:1pt solid #000000;padding:0.097cm;"| In this tutorial we tutorial we will learn usage of '''sed '''command. We will do this through some examples.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display slide 3

System Requirement
| style="border:1pt solid #000000;padding:0.097cm;"| To record this tutorial, I am using

''' Linux''' '''Operating System''' and

'''GNU BASH''' version 4.2.24

Please note,''' GNU bash''' version 4 or above is recommended to practice this tutorial.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display slide 4

Prerequisites
| style="border:1pt solid #000000;padding:0.097cm;"| As prerequisites

You should know Basics of linux terminal

For relevant tutorials please visit our website which is as shown.

http://spoken-tutorial.org

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display slide 5

Introduction
Let us start with an introduction to sed.
| style="border:1pt solid #000000;padding:0.097cm;"| '''sed''' is one of the most versatile tool in Linux.

Its a stream editor.

'''sed''' finds some pattern of text in a particular location of a file.

It perform some display or editing function.

Editing like insertion, substitution, deletion in matched text.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Open the file seddemo.txt

<nowiki>[</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| Let us start with some examples.

We will see how to print using the '''sed''' command.

I have a file called '''seddemo.txt''' in home directory.

Let us view its content.

In this file we have some enteries like roll no, name, stream, marks, pass or fail and the stipend amount.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| At the prompt

'''sed '2p' seddemo.txt'''<nowiki> [</nowiki>enter]

Hover your mouse on the second line
| style="border:1pt solid #000000;padding:0.097cm;"| Now suppose we want to print the second line of the file.

For this we need to oepn the terminal by pressing

Now Type:

'''sed''' space (in single quotes) ‘'''2p’''' space '''seddemo.txt'''

'''Press Enter'''

|-
| style="border:1pt solid #000000;padding:0.097cm;"|
| style="border:1pt solid #000000;padding:0.097cm;"| Here '''2''' denotes the location which is the second line.

'''p''' denotes the action, which is printing('''p''').

Look at the output.

It shows the entire file but see that the second line is printed twice.

This is the default behaviour of the action '''p'''.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| At the prompt

'''sed -n '2p' seddemo.txt'''

<nowiki>[</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| To only print the second line

type:

'''sed '''space (minus) '''-n''' space (within single quotes) '''2p''' space '''seddemo.txt '''

'''Press Enter.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| '''Highlight'''

'''-n'''

'''2'''

'''p'''

'''seddemo.txt'''

We see only the second line is printed.

| style="border:1pt solid #0000x00;padding:0.176cm;"| '''-n''' stands for ‘silent mode’ which will suppress all unnecessary output.

Then we give the location in the stream that we want to edit or display.

We want to select the second line.

'''p''' indicates the action we want to take ie to print the second line.

And '''seddemo.txt''' is the name of the file

This is the general syntax of sed command.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| At the prompt

'''sed -n '$p' seddemo.txt'''

<nowiki>[</nowiki>enter]

| style="border:1pt solid #000000;padding:0.097cm;"| Now let us print the last line of the file.
Let me clear the prompt

Now type: '''sed''' space (minus) '''-n''' space (in single quotes) (dollar) '''$p''' space '''seddemo.txt '''

Press '''Enter'''.

We see that the last line is printed.

Now come back to the text editor.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| At the prompt

'''sed -n '3,6p' seddemo.txt'''

<nowiki>[</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| Suppose we want to print the enteries from 3rd to 6th

For this we need to type on the terminal:

'''sed''' space (minus) '''-n''' space (in single quotes) ‘'''3''' (comma) ''',6p’''' space '''seddemo.txt '''

'''Press Enter.'''

The output is displayed from the third line to the sixth line.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| At the prompt

'''sed -n '3,6!p' seddemo.txt'''

<nowiki>[</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| Any of the actions can be reversed by using the exclamation mark before the action.

Say if we had to print all lines except from 3rd to 6th we would type:

'''sed''' space (minus) '''-n''' space (in single quotes) ‘'''3''' (comma) ''',6''' (exclamation mark) '''!p''' space '''seddemo.txt '''

'''Press''' '''Enter.'''

The output is displayed.
Let us switch back to the slides.
Line addressing and context addressing.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display slide 6
| style="border:1pt solid #000000;padding:0.097cm;"| So far, we specified the lines in the file on which the action needs to be taken.

This is known as line addressing.

Address specified by the line numbers.

This is one way of addressing.

Another way of addressing is '''Context addressing'''

Lines that contain particular context say a particular word.

If we want to take actions on lines that contain a particular word we use context addressing.

Regular expressions can be used.

Let us see an example.

Come back to our editor.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| At the prompt

'''sed -n<nowiki> '/[</nowiki>cC]omputers/p' seddemo.txt'''

<nowiki>[</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| Say we want to print those lines which have the word '''computers'''.

Come back to our temrinal.

Type:
'''sed''' space (minus) '''-n''' space (in single quotes) (front slash)(opening square bracket small c) (opening square bracket) (front slash) ‘/'''<nowiki>[</nowiki>cC]omputers/p '''space '''seddemo.txt '''

'''Press''' '''Enter.'''

We see the lines with the word computers is displayed.

We write pattern within square brackets. This is to match any one or both of the characters within square brackets.

When we need to match patterns the pattern needs to be typed between front slashes.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| At the prompt

'''sed -n<nowiki> '/[</nowiki>cC]omputers/w computer_student' seddemo.txt'''

<nowiki>[</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| We can print it in file as well using the '''w''' option.

For this type:

'''sed''' space (minus) '''-n''' space (in single quotes) (front slash) (opening square bracket) '''<nowiki>/[</nowiki>cC]omputers/w''' space '''computer_student''' space '''seddemo.txt '''

'''Press''' '''Enter.'''

Now all the matching lines would be transferred to the file '''computer_student.txt'''.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| At the prompt

'''cat computer_student'''

<nowiki>[</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| Let us view the content of '''computer_student'''

type:

'''cat''' space '''computer_student'''

'''Press Enter.'''

|-
| style="border:1pt solid #000000;padding:0.097cm;"| At the prompt

'''sed -n -e '/electronics/w electro’ -e'''

'''‘/civil/w civil' seddemo.txt'''”

<nowiki>[</nowiki>enter]

| style="border:1pt solid #000000;padding:0.097cm;"| We can also have patterns that we can write to different files.

Type:

'''sed''' space (minus) '''-n''' space (minus) '''-e''' space (in single quotes) (front slash) '''‘/electronics/w''' space '''electro.txt’''' (minus) '''-e''' space (in single quotes) (front slash) '''‘/civil/w''' space '''civil.txt’''' space '''seddemo.txt '''

Press '''Enter'''

'''-e''' is used to combine multiple methods''' '''

'''Press Enter'''

This would create two files '''electro.txt''' and '''civil.txt'''.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| '''cat electro'''

<nowiki>[</nowiki>enter]

'''cat civil'''

<nowiki>[</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| To see what they contain type:

'''cat '''space''' electro.txt'''

This will display the enteries with the word electronics.

Let us see the content of civil file.

Then type:

'''cat '''space''' civil.txt'''

''' press Enter'''

This will display the enteries having the word civil.

|-
| style="border:1pt solid #000000;padding:0.097cm;"|
| style="border:1pt solid #000000;padding:0.097cm;"| We will see some more set of commands in another tutorial.

I will use the same program.
This bring us to the end of the tutorial. Let us switch back to our slides

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display slide 7

Summary
| style="border:1pt solid #000000;padding:0.097cm;"| Let us summarize,

In this tutorial we learnt,

sed.

To print using sed.

Line Addressing.

Context Addressing.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Assignment
| style="border:1pt solid #000000;padding:0.097cm;"| As an assignment,

Use the same text file '''seddemo.txt.'''

Try to print records from 6th to 12th line.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 8

Acknowledgement Slide
| style="border:1pt solid #000000;padding:0.097cm;"| Watch the video available at the link shown below

It summarises the Spoken Tutorial project

If you do not have good bandwidth, you can download and watch it

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 9

Spoken Tutorial Workshops
| style="border:1pt solid #000000;padding:0.097cm;"| The Spoken Tutorial Project Team

Conducts workshops using spoken tutorials

Gives certificates to those who pass an online test

For more details, please write to

contact@spoken-tutorial.org

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 10

Acknowledgement
| style="border:1pt solid #000000;padding:0.097cm;"| Spoken Tutorial Project is a part of the Talk to a Teacher project

It is supported by the National Mission on Education through ICT, MHRD, Government of India

More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro

|-
| style="border:1pt solid #000000;padding:0.097cm;"| No Last Slide for tutorials created at IITB

Display the previous slide only and narrate this line.
| style="border:1pt solid #000000;padding:0.097cm;"|

|}

BOSS-Linux/C3/The-sed-command/English - Revision history

PoojaMoolya: Created page with "Sachin p: review done'''Title of script''': sed - The stream editor '''Author: Sachin Patil and Anirban''' '''Keywords: stream, editor, display, substitute, insert, delete'..."