BASH/C3/More-on-Redirection/English - Revision history

Nancyvarkey at 12:18, 8 August 2014

2014-08-08T12:18:59Z

Ashwini at 11:11, 8 August 2014

2014-08-08T11:11:20Z

Ashwini at 12:40, 5 August 2014

2014-08-05T12:40:23Z

Ashwini: Created page with ''''''' '''Title of script: More on redirection''' '''Author:''' Lavitha Pereira '''Keywords: Video tutorial, Error and output redirection, Append output''' {| style="bord…'

2014-08-05T12:28:54Z

Created page with ''''''' '''Title of script: More on redirection''' '''Author:''' Lavitha Pereira '''Keywords: Video tutorial, Error and output redirection, Append output''' {| style="bord…'

New page

''''''

'''Title of script: More on redirection'''

'''Author:''' Lavitha Pereira

'''Keywords: Video tutorial, Error and output redirection, Append output'''

{| style="border-spacing:0;"
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>'''Visual Cue'''</center>
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| <center>'''Narration'''</center>

|-
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 1
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Dear friends, Welcome to the spoken tutorial on''' More on redirection'''

|-
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 2
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| In this tutorial, we will learn

* '''Redirection''' of both s'''tandard error '''and''' output '''
* Appending redirected output
* With the help of some examples

|-
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 3'''Prerequisites'''

| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| To follow this tutorial you should have knowledge of '''Shell Scripting''' in''' BASH.'''

If not, for relevant tutorials please visit our website which is as shown,'''(http://www.spoken-tutorial.org)'''

|-
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 4

'''System requirements'''
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| For this tutorial I am using''' '''

* '''Ubuntu Linux''' 12.04''' '''Operating System and
* '''GNU BASH''' version 4.2

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

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"|
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| In an earlier tutorial, we learned about standard output and standard errors.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 5

'''Redirection''' of both '''stderr''' and '''stdout'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| * '''Both stdout''' as well as the '''stderr''' can be redirected to the same file.
* This can be done in multiple methods.

We will cover two of the most important methods of redirections in this tutorial.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 6

'''Redirection of both stderr and stdout'''

Syntax:

command &>filename

| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| The first method to redirect both the '''standard output '''and''' error''' is by using

'''&>'''

'''ampersand '''followed by''' greater-than sign'''

The syntax is

'''Command space ampersand greater than''' '''space filename'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"|
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Let me open a file named '''redirect.sh. '''

I have typed some code in this file.

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| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Highlight

'''<nowiki>#!/usr/bin/env bash </nowiki>'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| This is the''' shebang line.'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| '''ls /usr /user &> out_file'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| '''ls '''lists the directory content of 2 directories namely ''''/usr' '''and ''''/user''''

Note that ''''/user' '''directory does not exist.

Hence the command ''''ls'''' will throw an error.

And '''ampersand '''followed by '''greater than '''will redirect '''stdout '''and '''stderr''' to '''out_file.txt'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Press '''Ctrl+S'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Save the file.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Switch to '''terminal'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Let us run the file''' redirect.sh.'''

Go to the '''terminal.'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Type''' '''

'''chmod +x redirect.sh>>'''Press '''Enter'''

'''dot slash redirect.sh'''

| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| And type:'''chmod space plus x space redirect dot sh'''

Press '''Enter.'''

Type '''dot slash redirect.sh'''

Press '''Enter.'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Terminal

'''cat out_file.txt'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| We can see the output by opening '''out_file.txt'''

Type''' cat space out_file.txt'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| '''Output'''

'''<nowiki>[Highlight]</nowiki>'''

ls: cannot access /user: No such file or directory

/usr:

arm-linux-gnueabi

arm-linux-gnueabihf

bin

games

i686-linux-gnu

include

lib

local

sbin

share

src
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| We can see both the''' error '''and '''output.'''

The error for directory '''/user '''is recorded in this file.

It says that there was no ''''/user'''' directory found.

The directory content for '''/usr '''is displayed.

Please note that the content for ''''/usr' directory''' may vary on your system.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Type '''rm out_file.txt'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Now let us delete this file. So, on the '''terminal '''type

'''rm out_file.txt'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| *
**

| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Come back to our slides.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 7

'''Redirection of both stderr and stdou'''t

Syntax:

'''command > filename 2>&1'''

'''command >/dev/null 2>&1'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Another method is to use

'''2>&1 '''

'''2 greater than ampersand 1 '''after the filename

The syntax is'''command space greater than'''

'''filename space 2 greater than ampersand 1'''We can also redirect to '''slash dev slash null (/dev/null) '''file.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"|
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Let us learn a little more about '''slash dev slash null (/dev/null) '''file.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display slide 8

'''/dev/null '''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| * It is a special kind of file
* It is a null file or a place where we can dump anything.
* It includes the output and error messages ''Reply to Nancy Varkey (07/24/2014, 20:56): "..."''<br/> It depends upon the user, if he wants to discard some error messages as well as useful log messages he can 'dump' to /dev/null. ''Reply to nancy (07/25/2014, 10:56): "..."''<br/> ''Yes, we can dump anything(also the entire disk partition). Please see appended text.''we want to discard
* It is also called as '''bit bucket.'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"|
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Let us now come back to our code in '''gedit'''.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"|
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Let us redirect both standard output and error to the '''null file. '''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| '''ls /usr /user &> out_file.txt'''

| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| I will copy this line of code and paste it below over here.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| And replace the '''out_file.txt '''with

'''/dev/null 2>&1'''

So, we have

'''ls /usr /user >/dev/null 2>&1'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| I want both the output and error messages to be discarded.

So I will change this part of the copied code.'''> (greater than) '''means '''truncate''' or '''write'''.

'''/dev/null '''is the null file

'''2>&1''' '''(2 greater than ampersand 1)'''

Number “2” will redirect '''standard error '''to '''standard output, '''denoted by number “1”.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Press '''Ctrl+S'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Save the code.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Switch to '''terminal'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Let us run the file''' redirect.sh.'''

Go to the '''terminal.'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| '''dot slash redirect.sh'''

| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Recall the previous command with the up-arrow key.

'''dot slash redirect.sh'''

and press '''Enter.'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Terminal
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| We can see the output by typing

'''cat out_file.txt'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 9

'''Appen redirected output'''

'''Synatx:'''

'''command >> filename'''

| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Come back to our slides.

* We can capture as well as append '''standard output''' or '''error''' to a file.
* The output or the error will be appended at the end of the file.
* If the file does not exist, it will create a new file.

The syntax is:'''command''' '''space greater than greater than space '''followed by '''filename '''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"|
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Let us understand this using an example.

Let me open the file '''redirect.sh'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| date >> out_file.txt
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Now, here let's type

'''date space greater than greater than space out_file.txt'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Switch to the terminal and type:

'''date'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| The ''''date'''' command will simply display the Is this better than “correct date”?''Reply to Nancy Varkey (07/24/2014, 19:52): "..."''

I m sorry, my bad. It was a typo. The word was “current” and not “correct”

<nowiki>;)</nowiki>''Reply to sachin (25/07/2014, 10:14): "..."''

So which word is more appropriate -

“system date” or “currnet date”?''Reply to nancy (07/25/2014, 10:55): "..."''

“System date” is OK'''system date '''as output.

We can check this command on the '''terminal''' by typing ''''date'.'''

You can see that the '''system date '''i.e. the '''current date '''is displayed.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Highlight the '''date command code line'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Now come back to our code file.

The output of '''date command''' will be appended to the '''out_file.txt '''file.

We are using this file to capture''' '''standard output and error of ''''ls' '''command.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"|
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Switch to the '''terminal.'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| '''dot slash redirect.sh'''

| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Now press the '''uparrow''' key.

Recall the previous command and press '''Enter.'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| '''cat out_file.txt'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Let us check the output by opening '''out_file.txt'''

Type''' cat space out underscore out_file.txt'''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| '''<nowiki>[Highligh]</nowiki>'''

Wed Jul 2 12:06:32 IST 2014
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Observe that the output of ''''date'''' command is appended to the end of the file.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"|
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| This brings us to the end of this tutorial.

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 14

Summary
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| '''Summary'''

Let us summarise.

In this tutorial we learnt

* Redirection of both standard error and output
* And to append the redirected output''' '''

|-
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display slide 15

'''Assignment'''
| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| As an assignment,# Create 'X_file.txt' file with some content.
# Redirect the content of both 'out_file.txt' and 'X_file.txt' to a new file.

|-
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 16

http://spoken-tutorial.org /What\_is\_a\_Spoken\_Tutorial

About the Spoken Tutorial Project
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| 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 #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 17

Spoken Tutorial Workshops
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| 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 #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 18

Acknowledgement
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| 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 #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Display Slide 19
| style="border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| The script has been contributed by FOSSEE and Spoken-Tutorial teams.

This is Ashwini from IIT Bombay.

Thank you for joining.

|}

@@ Line 317: / Line 317: @@
 '''command >> filename'''
@@ Line 366: / Line 365: @@
 We are using this file to capture''' '''standard output and error of ''''ls' '''command.
@@ Line 419: / Line 416: @@
 * Redirection of both standard error and output
 * And to append the redirected output''' '''
@@ Line 426: / Line 422: @@
 '''Assignment'''
-| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| As an assignment,# Create 'X_file.txt' file with some content.
+| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| As an assignment,
 # Redirect the content of both 'out_file.txt' and 'X_file.txt' to a new file.

@@ Line 109: / Line 109: @@
 |-
 | style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Press '''Ctrl+S'''
-| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Save the file.
+| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Now Save the file.
 |-
@@ Line 115: / Line 115: @@
 | style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Let us run the file''' redirect.sh.'''
-Go to the '''terminal.'''
+Open the terminal using '''CTRL+ALT+T keys'''
 |-
@@ Line 236: / Line 238: @@
 | style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| * It is a special kind of file
 * It is a null file or a place where we can dump anything.
-* It includes the output and error messages '''<br/> It depends upon the user, if he wants to discard some error messages as well as useful log messages he can 'dump' to /dev/null. ''<br/> ''Yes, we can dump anything(also the entire disk partition). Please see appended text.''we want to discard
+* It includes the output and error messages
 * It is also called as '''bit bucket.'''
@@ Line 280: / Line 282: @@
 |-
 | style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Press '''Ctrl+S'''
-| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Save the code.
+| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Now click on Save. Save the code.
 |-
@@ Line 343: / Line 345: @@
 '''date'''
-| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| The ''''date'''' command will simply display the Is this better than “correct date”?
+| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| The ''''date'''' command will simply display the '''system date '''as output.
-<nowiki>;)</nowiki>
+We can check this command on the '''terminal''' by typing ''''date'.'''
-So which word is more appropriate -
-We can check this command on the '''terminal''' by typing ''''date'.'''
+Type: '''date'''
-−
 You can see that the '''system date '''i.e. the '''current date '''is displayed.
@@ Line 368: / Line 366: @@
 We are using this file to capture''' '''standard output and error of ''''ls' '''command.
 |-
 | style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"|
-| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Switch to the '''terminal.'''
+| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| Click on Save
 |-
@@ Line 381: / Line 384: @@
-Recall the previous command and press '''Enter.'''
+Recall the previous command
 |-

@@ Line 236: / Line 236: @@
 | style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| * It is a special kind of file
 * It is a null file or a place where we can dump anything.
-* It includes the output and error messages ''Reply to Nancy Varkey (07/24/2014, 20:56): "..."''<br/> It depends upon the user, if he wants to discard some error messages as well as useful log messages he can 'dump' to /dev/null. ''Reply to nancy (07/25/2014, 10:56): "..."''<br/> ''Yes, we can dump anything(also the entire disk partition). Please see appended text.''we want to discard
+* It includes the output and error messages '''<br/> It depends upon the user, if he wants to discard some error messages as well as useful log messages he can 'dump' to /dev/null. ''<br/> ''Yes, we can dump anything(also the entire disk partition). Please see appended text.''we want to discard
 * It is also called as '''bit bucket.'''
@@ Line 343: / Line 343: @@
 '''date'''
-| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| The ''''date'''' command will simply display the Is this better than “correct date”?''Reply to Nancy Varkey (07/24/2014, 19:52): "..."''
+| style="border-top:none;border-bottom:1pt solid #000001;border-left:1pt solid #000001;border-right:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.191cm;padding-right:0.191cm;"| The ''''date'''' command will simply display the Is this better than “correct date”?
 I m sorry, my bad. It was a typo. The word was “current” and not “correct”
-<nowiki>;)</nowiki>''Reply to sachin (25/07/2014, 10:14): "..."''
+<nowiki>;)</nowiki>
-−
 So which word is more appropriate -
-“system date” or “currnet date”?''Reply to nancy (07/25/2014, 10:55): "..."''
+“system date” or “currnet date”?
-−
 “System date” is OK'''system date '''as output.

BASH/C3/More-on-Redirection/English - Revision history

Nancyvarkey at 12:18, 8 August 2014

Ashwini at 11:11, 8 August 2014

Ashwini at 12:40, 5 August 2014

Ashwini: Created page with ''''­''' '''Title of script: More on redirection''' '''Author:''' Lavitha Pereira '''Keywords: Video tutorial, Error and output redirection, Append output''' {| style="bord…'

Ashwini: Created page with ''''''' '''Title of script: More on redirection''' '''Author:''' Lavitha Pereira '''Keywords: Video tutorial, Error and output redirection, Append output''' {| style="bord…'