When would you use the command 'ln' without any options?

Using the command 'ln' without any options is primarily for creating a hard link. A hard link allows you to reference the same inode of a file, meaning that the two links point to the same data on the disk. This can be useful for maintaining multiple directory entries for a single file, ensuring that you can access the same data under different names or locations in the filesystem.

For example, when you execute 'ln source_file hard_link', a new directory entry called 'hard_link' is created that points to the same data as 'source_file'. This hard link continues to function even if the original 'source_file' is deleted, as the data still exists as long as at least one link (or reference) to it remains.

The other options don't accurately describe the use of 'ln' without options: creating a temporary link is not a standard use case for 'ln'; deleting a file is done with commands like 'rm'; and displaying file contents is done using commands like 'cat' or 'less'. Thus, the command is specifically designed for linking files, establishing that the creation of hard links is the correct context in which to interpret its use without any additional options.