Shell Programming and Scripting

Don't get too distracted with the here-document construct. It is the same as if you saved it into a file, and then fed the file into a while loop via < operator:

Code:

while [] ; do 
   ...
done < file

That open descriptor won't get closed until the while loop is over. In your case never. So read still is reading from that file descriptor (which is not stdin).

The usual construct

Code:

while read line ; do 
   #something with $line
done < file

uses the return value of read builtin (effectively getline() function), which will terminate the while loop when eof encountered.