Question

Which command is used to hold open a very short or zero-length file?

Answer 1

A zero-byte file or zero-length file is a computer file containing no data; that is, it has a length or size of zero bytes.In some cases, zero-byte files may be used to convey information like file metadata ; or to put in a directory to ensure that it is nonempty, since some tools such as backup and revision control software may ignore the empty directories.

There are many ways that could manually create a zero-byte file, for example, saving empty content in a text editor, using utilities provided by operating systems, or programming to create it. On Unix-like systems, the shell command $ touch filename results in a zero-byte file filename. Zero-byte files may arise in cases where a program creates a file but aborts or is interrupted prematurely while writing to it. Because writes are cached in memory and only flushed to disk at a later time (page cache), a program that does not flush its writes to disk or terminate normally may result in a zero-byte file. When the zero-byte file is made, file system does not record the file's content on storage, but only updates its index table.

Sometimes zero-byte files may be created on purpose, just to provide some extra information to a folder listing, the same way you might create an empty folder to provide some extra meaning. For example, an empty file named __PRIVATE__ or FILES RELOCATED TO X