Perl Programming/Keywords/warn

The warn keyword
warn prints the LIST to STDERR. If the last LIST element is not a newline, it appends the same file/line number text as die does. If the output is empty and the variable $@ contains already a value, this is used after appending "\t...caught" to <tt>$@</tt>. If this variable is empty, the string <tt>"Warning: Something's wrong"</tt> is used.

If a <tt>$SIG{__WARN__}</tt> is installed, no message is printed. With the <tt>__WARN__</tt> handler, all the warnings can be suppressed.