Final answer:
To create a backup of a file, use the cp command in a Unix-like OS to copy the original file to a new file named as the backup.
Step-by-step explanation:
When creating a backup of a file, the cp command in a Unix-like operating system can be used. To create a backup, open the terminal (or command prompt in Windows) and type the command cp original_file.txt backup_file.txt. This command will create a copy of 'original_file.txt' and name it 'backup_file.txt', effectively creating the desired backup. It is important to be in the correct directory where the original file is located or to specify the full path to the file.