Exercise

Output and Redirection Exercise

Overview

In this hands-on exercise, you will compare the overwrite operator (>) with the append operator (>>). You will deliberately overwrite one file, then create a second file and add lines without replacing its existing content.

Target host: servera

Connect to the lab host

From your lab workstation, connect to servera and clear the terminal.
```
ssh student@servera
```
Create an important file

Open a new file in Vim.
```
vim evil_plan.md
```
Press i to enter Insert mode, then enter the following text.
```
== Plan for World Domination! ==
1. Make humanity reliant on AI by having students use AI to do their homework
...
13. Poison the training data for all new AIs
...
96. Become the supreme-leader of the world!
```
Press Esc to return to Normal mode. Type :, enter wq, and press Enter to write the file and quit Vim.
Verify the file

Display the file and confirm that it contains your plan.
```
cat evil_plan.md
```
Redirect output with the overwrite operator

Try to add one last step by redirecting the output from echo with a single greater-than sign.
```
echo "97. Call mom and tell her the good news about world domination" > evil_plan.md
```
Display the file again.
```
cat evil_plan.md
```
What happened? The > operator opened the destination for writing and replaced its previous contents. The file now contains only the final line.

Create a new file and append content

Start a second plan. Use > once to create the file, then use >> to append the next two lines.

echo "== Eviler Plan for World Domination! ==" > evil_plan-v2.md
echo "1. Invent a <Top Secret Information Redacted>" >> evil_plan-v2.md
echo "2. Use the <Top Secret Information Redacted> to poison the minds of <Top Secret Information Redacted>" >> evil_plan-v2.md

Display the second file and confirm that all three lines remain.

cat evil_plan-v2.md

Append one more line

Use >> again to add another line without replacing the existing plan.
```
echo "3. Call mom and tell her the good news about world domination" >> evil_plan-v2.md
```
Verify the result.
```
cat evil_plan-v2.md
```
Key idea Use > when you intend to replace a file's contents. Use >> when you intend to add output after the file's existing contents.
Clean up

Remove both files created during the exercise.
```
rm evil_plan.md evil_plan-v2.md
```

Overview

Connect to the lab host

Create an important file

Verify the file

Redirect output with the overwrite operator

Create a new file and append content

Append one more line

Clean up