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 $@. If this variable is empty, the string "Warning: Something's wrong" is used.

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

  warn LIST

warn "\$foo is alive and $foo!";