How to check if the file exists?

You can check if a file exists in a shell script using the test command or the [ ] syntax. Here’s a simple example in a shell script:

#!/bin/bash

FILENAME="CharacterSpace.java"

if [ -e "$FILENAME" ]; then
    echo "File $FILENAME exists."
else
    echo "File $FILENAME does not exist."
fi

Steps to Use the Script:

Create a new script file:
```
nano check_file.sh
```
Copy and paste the above code into the file.
Save and exit the editor.
Make the script executable:
```
chmod +x check_file.sh
```
Run the script:
```
./check_file.sh
```

This script will check if CharacterSpace.java exists and print the appropriate message.