Ashwini at 10:26, 14 December 2013

2013-12-14T10:26:32Z

Ashwini at 09:40, 14 December 2013

2013-12-14T09:40:30Z

Ashwini: Created page with 'Sachin p: review done'''Title of script''': sed - The stream editor '''Author: Sachin Patil''' '''Keywords: stream, editor, display, substitute, insert, delete''' {| style=…'

2013-07-01T09:45:43Z

Created page with 'Sachin p: review done'''Title of script''': sed - The stream editor '''Author: Sachin Patil''' '''Keywords: stream, editor, display, substitute, insert, delete''' {| style=…'

New page

Sachin p:

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

'''Author: Sachin Patil'''

'''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.

|-
| 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

'''Ubuntu Linux''' 12.04''' Operating System''' and

'''GNU BASH''' version 4.2.24(1)

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;"| To practice this tutorial,

You should know Basics of linux terminal

For relevant tutorials please visit our website:

http://spoken-tutorial.org

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

Introduction
| 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.

Then it behave as a display or editing function.

It performs editing like insertion, substitution, deletion of the 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 first start with some examples.

Let us see how to print using the '''sed''' command.

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

Let us view its content .

|-
| 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 '''seddemo.txt'''.

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

'''Press Enter.'''

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

'''-n'''

'''2'''

'''p'''

'''seddemo.txt'''
| style="border:1pt solid #000000;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;"| To print the last line

type:

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

Press Enter.

|-
| 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;"| To print from 3rd to 6th line

type:

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

'''Press Enter.'''

|-
| 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.'''

|-
| 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 one way of addressing called '''Line Addressing'''.

But if we want to take actions on lines that contain a particular word.

For such issues the other way of addressing is '''Context Addressing. '''

We can use regular expressions.

Let us see an example.

|-
| 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'''.

We type:

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

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

The lines where the word computers are displayed.

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

Type at the prompt:

'''sed''' space (minus) '''-n''' space (in single quotes) (front slash) (opening angle bracket) (opening angle bracket) (front slash) '''<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'''.

|-
| 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;"| To 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’''' (minus) '''-e''' space (in single quotes) (front slash) '''‘/civil/w''' space '''civil’''' space '''seddemo.txt '''

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

'''Press Enter'''

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

|-
| 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'''

'''Press Enter'''

Then type:

'''cat '''space''' civil'''

And''' press Enter'''

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

I will use the same program file.

|-
| 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

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| 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;"|

|}

@@ Line 3: / Line 3: @@
 review done'''Title of script''': sed - The stream editor
-'''Author: Sachin Patil'''
+'''Author: Sachin Patil and Anirban'''
 '''Keywords: stream, editor, display, substitute, insert, delete'''

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

Ashwini at 10:26, 14 December 2013

Ashwini at 09:40, 14 December 2013

Ashwini: Created page with 'Sachin p: review done'''Title of script''': sed - The stream editor '''Author: Sachin Patil''' '''Keywords: stream, editor, display, substitute, insert, delete''' {| style=…'