Search notes:

oradebug direct_access

oradebug help direct_access
DIRECT_ACCESS  <set/enable/disable command | select query> Fixed table access

oradebug direct_access enable trace

oradebug direct_access disable reply

oradebug direct_access set mode = unsafe

oradebug direct_access set content_type = 'text/plain'
oradebug direct_access set content_type = 'text/xml'
Dump the result of query on a fixed table to the trace file. 
oradebug direct_access select * from x$bh

See also

$ORACLE_HOME/rdbms/admin/hangdiag.sql makes extensive use of oradebug direct_access.
ORA-15655: Fixed table "…" cannot be accessed safely in prelim connection
ORA-15653: Fixed table "…" is not supported by DIRECT_ACCESS

Index

Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 8 attempt to write a readonly database in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php:78 Stack trace: #0 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(78): PDOStatement->execute(Array) #1 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(30): insert_webrequest_('/notes/developm...', 1745915626, '3.14.15.223', 'Mozilla/5.0 App...', NULL) #2 /home/httpd/vhosts/renenyffenegger.ch/httpsdocs/notes/development/databases/Oracle/tools/oradebug/direct_access/index(61): insert_webrequest() #3 {main} thrown in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php on line 78