In the third edition of "Learning the Bash shell" by Newham and Rosenblatt it is written in page 15 as a comment:
if a particular UNIX utility doesn't accept standard input when you leave out the filename argument, try using a dash (0) as the argument. Some NIX systems provide standard input as a file so you could try providing the file /dev/stdin as the input file argumnet.
The last sentence isn't clear to me - what's the meaning of "provide standard input as a file"?
Isn't it dangerous to "repeatedly" create files named
/dev/stdin in a system (I personally use Ubuntu 16.04).
BTW I came across a similar case in this post.