Difference between revisions of "Tutorial5: Redirection"

From CDOT Wiki
Jump to: navigation, search
(Additional File Manipulation Commands)
(Additional File Manipulation Commands)
Line 63: Line 63:
 
There are some additional regular file manipulation commands that you can use with redirection<br>(in addition to the other regular file manipulation commands introduced in week 2). These commands are displayed in the table below:
 
There are some additional regular file manipulation commands that you can use with redirection<br>(in addition to the other regular file manipulation commands introduced in week 2). These commands are displayed in the table below:
  
<table cellpadding="5"><tr><th style="border-bottom: 1px solid black;text-align:left;">Linux Command</th><th style="border-bottom: 1px solid black;text-align:left;">Purpose</th></tr><tr valign="top"><td>'''cut'''</td><td>Used to extract fields and characters from records. The option '''-c''' option is used to cut by a character or a range of characters. The '''-f''' option indicates the field number or field range to display (this may require using the '''-d''' option to indicate the field separator (delimiter).<br><br>''Examples:''<br><br>'''cut -f2 filename''' - extract 2nd field from all records in file, using tab as delimiter (default)<br>'''cut -d' ' -f2,5 filename''' - extract 2nd and 5th field, using space as delimiter<br>'''cut -d' ' -f1-3,5 filename''' - extract 1st through 3rd and 5th fields, using space as delimiter<br>'''cut -c3-5 filename''' - extract 3rd to 5th characters</td></tr><tr><td>'''tr'''</td><td>x</td></tr><tr><td>'''wc'''</td><td>x</td></tr></table>
+
<table cellpadding="5"><tr><th style="border-bottom: 1px solid black;text-align:left;">Linux Command</th><th style="border-bottom: 1px solid black;text-align:left;">Purpose</th></tr><tr valign="top"><td>'''cut'''</td><td>Used to extract fields and characters from records. The option '''-c''' option is used to cut by a character or a range of characters. The '''-f''' option indicates the field number or field range to display (this may require using the '''-d''' option to indicate the field separator (delimiter).<br>''Examples:''<br>'''cut -f2 filename''' - extract 2nd field from all records in file, using tab as delimiter (default)<br>'''cut -d' ' -f2,5 filename''' - extract 2nd and 5th field, using space as delimiter<br>'''cut -d' ' -f1-3,5 filename''' - extract 1st through 3rd and 5th fields, using space as delimiter<br>'''cut -c3-5 filename''' - extract 3rd to 5th characters</td></tr><tr><td>'''tr'''</td><td>x</td></tr><tr><td>'''wc'''</td><td>x</td></tr></table>
  
 
===Piping (Using Pipes)===
 
===Piping (Using Pipes)===

Revision as of 13:24, 23 January 2020

REDIRECTION: STANDARD INPUT / STANDARD OUTPUT / STANDARD ERROR


Main Objectives of this Practice Tutorial

  • x
  • x
  • x
  • x

Tutorial Reference Material

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


Redirection
  • Standard Input (stdin)
  • Standard Output (stdout)
  • Standard Error (stderr)
  • Piping (pipes)

Multiple Commands

  • Semicolon
  • Grouping ( )


Redirection Filters
  • head
  • tail
  • sort
  • grep
  • cut
  • tr
  • wc
Brauer Instructional Videos:

KEY CONCEPTS

Redirection (Standard Input, Standard Output, Standard Error)

... standard streams are preconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin), standard output (stdout) and standard error (stderr). Originally I/O happened via a physically connected system console (input via keyboard, output via monitor), but standard streams abstract this. When a command is executed via an interactive shell, the streams are typically connected to the text terminal on which the shell is running, but can be changed with redirection or a pipeline.

Reference: https://en.wikipedia.org/wiki/Standard_streams


Additional File Manipulation Commands

There are some additional regular file manipulation commands that you can use with redirection
(in addition to the other regular file manipulation commands introduced in week 2). These commands are displayed in the table below:

Linux CommandPurpose
cutUsed to extract fields and characters from records. The option -c option is used to cut by a character or a range of characters. The -f option indicates the field number or field range to display (this may require using the -d option to indicate the field separator (delimiter).
Examples:
cut -f2 filename - extract 2nd field from all records in file, using tab as delimiter (default)
cut -d' ' -f2,5 filename - extract 2nd and 5th field, using space as delimiter
cut -d' ' -f1-3,5 filename - extract 1st through 3rd and 5th fields, using space as delimiter
cut -c3-5 filename - extract 3rd to 5th characters
trx
wcx

Piping (Using Pipes)

x


Multiple Commands Using Semicolon ; / Grouping Commands ( )

x

INVESTIGATION 1: BASICS OF REDIRECTION


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



Perform the Following Steps:

  1. x

In the next investigation, you will ...

INVESTIGATION 2: REDIRECTION USING PIPES

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


Perform the Following Steps:

  1. x

In the next investigation, you will ...

INVESTIGATION 3: MULTIPLE COMMANDS / COMMAND GROUPING

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_week5_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
  9. Create a table listing each Linux command, useful options that were mentioned in the online assignment #1 and command purpose for the following Linux commands: cut , tr , wc