_lines - UDM Built-in Variable

The _lines built-in variable specifies whether or not the line number of a command (relative to the script in which it occurred) is printed with the error if the command cannot be parsed or is malformed.

_lines can have either of the following values:

yes	Line number is printed.
no	Line number is not printed.

_lines can be set using the set command:

set _lines=yes