Bash date arithmetic

Not really oracle but useful nevertheless
date -d "yesterday" +"%d %B %y"


http://www.walkernews.net/2007/06/03/date-arithmetic-in-linux-shell-scripts/




Convert comma separated list into an array - dbms_utility.comma_to_table

Simple way to convert a comma separated list held in a single variable into its component parts.
pl/sql equivalent to php explode
e.g.

SET SERVEROUTPUT ON
DECLARE
l_list1   VARCHAR2(50) := 'A,B,C,D,E,F,G,H,I,J';
l_list2   VARCHAR2(50);
l_tablen  BINARY_INTEGER;
l_tab     DBMS_UTILITY.uncl_array;
BEGIN
DBMS_OUTPUT.put_line('l_list1 : ' || l_list1);

DBMS_UTILITY.comma_to_table (
   list   => l_list1,
   tablen => l_tablen,
   tab    => l_tab);

FOR i IN 1 .. l_tablen LOOP
  DBMS_OUTPUT.put_line(i || ' : ' || l_tab(i));
END LOOP;

DBMS_UTILITY.table_to_comma (
   tab    => l_tab,
   tablen => l_tablen,
   list   => l_list2);

DBMS_OUTPUT.put_line('l_list2 : ' || l_list2);



END;

http://www.oracle-base.com/articles/9i/UsefulProceduresAndFunctions9i.php