DECLARE 

F1 UTL_FILE.FILE_TYPE; 

BEGIN 

F1 := UTL_FILE.FOPEN('MYDIR','MYFILE','R'); 
.
.
.
.
UTL_FILE.FCLOSE(F1);

END;

DECLARE 

DIRECTORY_NAME varchar2(100);

DIRECTORY_NAME := LOOKUP('MYDIR')  -- this is a function that looks up MYDIR from the Oracle Directory Table and returns the Path (/var/spool/hr).

F1 UTL_FILE.FILE_TYPE; 

BEGIN 

F1 := UTL_FILE.FOPEN(DIRECTORY_NAME,'MYFILE','R'); 
.
.
.
.
UTL_FILE.FCLOSE(F1);

END;

create or replace function LOOKUP (DirectoryName varchar2) return varchar2

Path varchar2(100);

begin
  select Path
    into Path 
    from all_directories
      where directory_name = DirectoryName;

  return Path

end;

DIRECTORY_NAME varchar2(100);

DIRECTORY_NAME := LOOKUP('MYDIR')  -- this is a function that looks up MYDIR from the Oracle Directory Table and returns the Path (/var/spool/hr).

F1 UTL_FILE.FILE_TYPE; 

F1 := UTL_FILE.FOPEN(DIRECTORY_NAME,'MYFILE','R'); 

UTL_FILE.FOPEN(DIRECTORY_NAME,'MYFILE','R');

MIKJ3DB1> select directory_path from all_directories where directory_name='MY_DIR';
DIRECTORY_PATH
------------------------------------------------------------------------------------
D:\Oracle\Save

MIKJ3DB1> declare F1 UTL_FILE.FILE_TYPE;
  2  begin
  3    F1 := UTL_FILE.FOPEN('MY_DIR','T.TXT','R');
  4    UTL_FILE.FCLOSE(F1);
  5    F1 := UTL_FILE.FOPEN('D:\Oracle\Save','T.TXT','R');
  6  end;
  7  /
declare F1 UTL_FILE.FILE_TYPE;
*
ERROR at line 1:
ORA-29280: invalid directory object
ORA-06512: at "SYS.UTL_FILE", line 41
ORA-06512: at "SYS.UTL_FILE", line 478
ORA-06512: at line 5

MIKJ3DB1> @v

Oracle version: 19.13.0.0.211019 EE - JVM v1.8.0_201 - timezone files v32