-- 1) Survey the sampling activity near the interesting event 
SELECT DISTINCT SAMPLE_ID, SAMPLE_TIME 
  FROM DBA_HIST_ACTIVE_SESS_HISTORY 
WHERE INSTANCE_NUMBER=:INSTNUM
AND SAMPLE_TIME > TO_DATE('2014-02-07 08:00','YYYY-MM-DD HH24:MI')
AND SAMPLE_TIME < TO_DATE('2014-02-07 09:00','YYYY-MM-DD HH24:MI')
ORDER BY 2;

-- 2) Get SQL running during the sample time
SELECT DHS.SQL_TEXT, 
       ASH.* 
  FROM DBA_HIST_ACTIVE_SESS_HISTORY ASH LEFT OUTER JOIN DBA_HIST_SQLTEXT DHS 
       ON ASH.SQL_ID=DHS.SQL_ID 

Environment Overview
To show info about currently running OMS including URLS, ports, and paths:

cd $OMS_HOME/bin
./emctl status oms -details

Reset Weblogic Admin Password
12c , 13c Cloud Control: Steps for Modifying the Password for Weblogic and Nodemanager User Accounts in the Enterprise Manager Installation (Doc ID 1450798.1)
Reset Weblogic Admin Server Password
Querying the Management Repository

• Download and run Vagrantfile from bmuschko's CKA Crash Course here.
  
• Initialize Kubernetes using these steps
  
• Set Kubelet IP addresses for each node (plan, worker1, worker2):
  

sudo vi /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

Add:

Find Apex Installations

SELECT * FROM ALL_USERS WHERE USERNAME LIKE 'APEX%';

Find Apex Workspaces

SELET WORKSPACE FROM APEX_nnnnnn.APEX_WORKSPACES;

Find Apex Users

SELECT USER_NAME FROM APEX_nnnnnn.WWV_FLOW_FND_USER;

My Session Info

-- My Session Info
select username, sid, serial#, terminal, program, machine from v$session where sid=userenv('sid');

List Blocking Sessions
By: Natalka Roshak

-- Definitions
select * from APEX_DICTIONARY;
select * from APEX_WORKSPACES;
select * from APEX_APPLICATIONS ORDER BY WORKSPACE, APPLICATION_ID;
select * from APEX_WORKSPACE_APEX_USERS;
select * from APEX_WORKSPACE_SCHEMAS;

-- Development
select * from APEX_DEBUG_MESSAGES;
select * from APEX_DEVELOPER_ACTIVITY_LOG;
select WORKSPACE_NAME, USER_NAME, IS_ADMIN, IS_APPLICATION_DEVELOPER, ACCOUNT_LOCKED  from APEX_WORKSPACE_DEVELOPERS ORDER BY 1,2;

-- Environment
select * from APEX_RELEASE;
select * from APEX_PATCHES;
select * from APEX_INSTANCE_PARAMETERS;

Javascript in SQLcl

Erik Van Roon series on SQLcl/Javascript :
Part 1 |
Part 2 |
Part 3

Github Oracle-db-tools/sqlcl/scripting

Finding file counts
For Linux:

cd $ORACLE_BASE/admin

-- For Linux
find -maxdepth 2 -type d | while read dir; do 
    count=$(find "$dir" -maxdepth 2 -iname \*.aud | wc -l)
    echo "$count ; $dir"
done | grep adump | sort -n

Getting around too many arguments:
This method is scalable, does not have issues with argument list limits, and works well for millions of files. This example looks for files that match *.aud.