When should I use `exit`?

You should use the exit command in the following scenarios:

Ending a Shell Session: When you want to terminate your current shell session, you can use exit. This is common when you are done working in the terminal.
```
exit
```
Exiting a Script: If you are writing a shell script and want to terminate the script at a certain point, you can use exit. You can also specify an exit status to indicate success or failure.
```
#!/bin/bash
echo "This is a script."
exit 0  # Indicates success
```
Conditional Exits: You can use exit in conditional statements within scripts to exit based on certain conditions.
```
if [ ! -f "important_file.txt" ]; then
    echo "File not found!"
    exit 1  # Indicates an error
fi
```
Exiting from a Subshell: If you are in a subshell (e.g., after using parentheses), you can use exit to terminate that subshell.
```
( 
    echo "Inside subshell"
    exit 0
)
```

In summary, use exit when you want to terminate a shell session or script, especially when you need to indicate a specific exit status.