?         : this help
 ??        : help pgbash usage
 ??h [SQL] : help SQL(or "SQL") syntax or all SQL reserved words
 ??e       : help SQLCODE (sql ERROR code)
 ??f       : help 'pgbashrc' FUNCTIONs for using a shell script
 ??o       : help 'exec_sql' options
 ?m        : show CONNECTION NAMEs
 ?o        : show current values of exec_sql_OPTIONs
 ?s        : show STATUS after executing SQL
 ?v        : show PostgreSQL and pgbash VERSION
 ?u        : list database USERs
 ?l        : list DATABASEs
 ?d  [rel] : list RELATIONs for table/view/index/sequence
 ?d{t|i|v} : list TABLEs/INDEXes/VIEWs
 ?dl       : list LARGE_OBJECTs
 ?dp       : list PERMISSIONs
 ?ds       : list SEQUENCEs
 ?dA       : list AGGREGATEs
 ?dD [obj] : list DESCRIPTIONs for table/type/function/operator
 ?dF       : list FUNCTIONs
 ?dO       : list OPERATORs
 ?dS       : list SYSTEM_TABLEs
 ?dT       : list data_TYPEs
 E{+|-}    : turn on/off ECHO_QUERY sent to the backend
 Q{+|-}    : turn on/off QUIET_MODE for system/sql error messages
 L{+|-}    : turn on/off OUTER_FRAME_print
 T{+|-}    : turn on/off TOP_header_print
 B{+|-}    : turn on/off BOTTOM_count_print 
 A{+|-}    : turn on/off ALIGNMENT of plain text
 X{+|-}    : turn on/off EXPANDED format 
 H{+|-}    : turn on/off HTML format
 S+  [chr] : set SEPARATOR  (e.g. ','  ) or DEFAULT('|')
 N+  [str] : set NULL_STRING(e.g. '*N*') or DEFAULT('')
 Z+  [str] : set ZERO_STRING(e.g. '*0*') or DEFAULT('')
 _lo_import : lo_import <INPUT_FILE_NAME> <'COMMENT'>
 _lo_export : lo_export <OID> <OUTPUT_FILE_NAME>
 _lo_unlink : lo_unlink <OID>