Rather search through manual pages (
man bash is your friend). Such special characters are hard to find in google. Basically you end up with this section:
Duplicating File Descriptors
The redirection operator
is used to duplicate input file descriptors. If
word expands to one or more digits, the file descriptor denoted by
n is made to be a copy of that file descriptor. If the digits in
word do not specify a file descriptor open for input, a redirection error occurs. If word evaluates to
-, file descriptor
n is closed. If
n is not specified, the standard input (file descriptor 0) is used.
So in the other words,
<&- means, that it basically closes
stdin, so the program running under
nohop really can not read anything from there.