Input-Output Redirection

Question 1

Redirect standard output to a file

Answer 1

echo “test” > file.txt

Question 2

Redirect and append standard output to a file

Answer 2

echo “test”&raquo_space; file.txt

Question 3

Chain scripts, files, and commands together by STDOUT as STDIN for the next command

Answer 3

|

cat /etc/passwd | grep root

Question 4

Redirect standard error

Answer 4

2>

Question 5

Redirect STDERR to STDOUT

Answer 5

2>&1

Question 6

Accept input from file

Answer 6

<

grep -i “ERROR” < /var/log/messages

Question 7

What is a “here document”

Answer 7

A way to run an interactive program within a shell script without user action by supplying the required input for the interactive program, or interactive shell script

Question 8

How do you use a here document

Answer 8

The general form for a here document is − 
command << delimiter
document
delimiter
The following script runs a session with the vi text editor and saves the input in the file test.txt.
#!/bin/sh

filename=test.txt
vi $filename <

Question 9

Describe each file descriptor

Answer 9

&0 is STDIN
&1 is STDOUT
&2 is STDERR

Question 10

Redirect STDOUT to STDERR

Answer 10

echo “test” >&2