extrait de man bash:
read [-ers] [-u fd] [-t timeout] [-a aname] [-p prompt] [-n nchars] [-d
delim] [name ...]
One line is read from the standard input, or from the file
descriptor fd supplied as an argument to the -u option, and the
first word is assigned to the first name, the second word to the
second name, and so on, with leftover words and their interven‐
ing separators assigned to the last name. If there are fewer
words read from the input stream than names, the remaining names
are assigned empty values. The characters in IFS are used to
split the line into words. The backslash character (\) may be
used to remove any special meaning for the next character read
and for line continuation. Options, if supplied, have the fol‐
lowing meanings:
la question restante étant comment ouvrir un fichier.
Ceci est expliqué dans redirecting input
Redirecting Input
Redirection of input causes the file whose name results from the expan‐
sion of word to be opened for reading on file descriptor n, or the
standard input (file descriptor 0) if n is not specified.
The general format for redirecting input is:
[n]<word