Dump an Oracle Block to the trace

This is the script I use to dump an Oracle block.

set pagesize 0
set def =
set def &
column header_block new_value m_block
column header_file new_value m_file

select
header_file,
header_block + &m_offset header_block
from
dba_segments
where
segment_name = upper('&m_segment')
and nvl(partition_name,'xxx') = nvl(upper('&m_partition'),'xxx')
and owner = upper('&m_owner')
;

alter system dump datafile &m_file block min &m_block block max &m_block;