title: What is the least memory usage for a binary file on UNIX-like OS?
body: <p>I'm actually attending an operating system course at university.
  The professor has told us about fread(), fwrite() ... C functions and read(), write() ... system calls.
  My doubt became when I had to define the block's size and the number of blocks. As the documentation says this functions return the exact number of blocks red or written.
  So my question is: is it possible to have a file on the hard disk smaller than one byte, or is possible to have a file which dimension is not a multiple of Byte?</p>
  
  <p>Thank you in advance.</p>
  
  <p>EDIT: as someone suggested I've not posted a practical example. This is the exercise I'm working on. It's just a program that clones a file
  <a href="https://gitlab.com/clementefnc/laboratori_so/blob/master/Lab01/Es4/Es4p4.c" rel="nofollow noreferrer">https://gitlab.com/clementefnc/laboratori_so/blob/master/Lab01/Es4/Es4p4.c</a></p>