specifies an optional
identifier to precede all lines after the first line. The following
are valid values for prefix-identifier:
HYPHEN
inserts a hyphen (-) before each message.
PLUS
inserts a plus sign (+) before each message.
Details
When the message is
more than one line long, all lines are written. When a prefix identifier
is specified, all lines after the first line are preceded by the prefix
identifier.