Lab 6: Input Output Redirection

Objective Focus
Understand and use essential tools
Create and edit text files
Use input-output redirection (>, », |, 2>, etc.)

Official RHCSA EX200 Exam Objectives

Looking At File Content as Terminal Output
 $ cat
  • concatenate files and print on the standard output
 $ less
  • allows a user to partially display content of a file
 $ more
  • has less options than $ less
 $ head
  • output the first part of files, default is first 10 lines
 $ tail
  • output the last part of files, default is last 10 lines
Understanding Input and Output Redirection
Input Output Error
< >, » 2>
$ out < in $ in > out $ in 2> errout
$ in » out
Example Use Cases
 $ grep -i "error" < samplelog.txt

Download sample file here!

 $ ip a > pcinfo.txt    

 $ hostname >> pcinfo.txt    
 $ hostname123 2> errout.txt

How to use pipes “|” in Linux

Using the “|” character is a form of redirection. It allows you to take output from one command to another.

 $ cmd1 | cmd2 | cmd3 |.....|cmd_x
Example Use Cases
 $ ip a | grep -i "inet" | awk '{print $1,$2}'

The above example shows us how we use available tools on the system for redirection. And how We could also redirect this output to a text file to share.

Redirections are very important to completing daily tasks in linux!

That’s it for lab 6!