How to change tomcat 8 port to 80

To run Tomcat on a port below 1024 in Ubuntu/Unix, the service needs root privileges.
And that you do not want. Use a port redirection via iptables

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8080

MongoDB SSL connection command

$ mongo --host <hostname> --port <port> --username username --password --ssl --sslPEMKeyFile <filename> --sslPEMKeyPassword <value> --sslCAFile <filename>

Manage Tablespaces

Create:
CREATE TABLESPACE DATA05 DATAFILE 'D:\app_db12c\oracle\oradata\orcl\sample01.dbf' SIZE 1M AUTOEXTEND ON NEXT 1M;

Extend:
ALTER TABLESPACE DATA05 ADD
  DATAFILE 'D:\app_db12c\oracle\oradata\orcl\sample02.dbf' SIZE 1M
  AUTOEXTEND ON NEXT 1M;

Delete:
DROP TABLESPACE DATA05 INCLUDING CONTENTS AND DATAFILES;

SQLPLUS command to start oracle pdbs

sqlplus sys/xxxxx as sysdba@pdborcl.xxxx.com

SQL*Plus: Release 12.1.0.2.0 Production on Fri Nov 4 12:07:01 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> SELECT name,open_mode from v$pdbs ORDER BY name;

NAME                           OPEN_MODE
------------------------------ ----------
PDB$SEED                       READ ONLY
PDBORCL                        MOUNTED

SQL> alter pluggable database pdborcl open read write;

Pluggable database altered.

SQL> SELECT name,open_mode from v$pdbs ORDER BY name;

NAME                           OPEN_MODE
------------------------------ ----------
PDB$SEED                       READ ONLY
PDBORCL                        READ WRITE

SQL>

How to modify vncveiwer settings on Windows 7?

To modify VNC Viewer/Server setting:-

1. Start -> regedit  to open Registry Editor
2. Navigate to HKEY_CURRENT_USER -> Software -> RealVNC  -> vncviewer
3. Select 'vncviewer' and modify ColorLevel to full to resolve 'Bad ColourLevel' while opening VNC Viewer.

NodeJS express security

app.use(session( {

httpOnly: true, // don't let browser javascript access cookies ever
secure: true, // only use cookies over https
ephemeral: true // delete this cookie when the browser is closed.

)});

EM Configuration issue.

bash-4.1$ emctl
EM Configuration issue. /opt/usr01/app/usr01/product/11.2.0/dbhome_1/<hostname>_orcl not found.

For above error saying missing _orcl directory, search for _orcl folder in your /opt/usr01/app/usr01/product/11.2.0/dbhome_1 and set the actual required hostname to ORACLE_HOSTNAME (typically It would be localhost)

bash-4.1$ export ORACLE_HOSTNAME=localhost
bash-4.1$ emctl (now works fine)
Oracle Enterprise Manager 11g Database Control Release 11.2.0.3.0
Copyright (c) 1996, 2011 Oracle Corporation.  All rights reserved.
   Oracle Enterprise Manager 10g Database Control commands:
        emctl start | stop dbconsole
        emctl status | secure | setpasswd dbconsole
        emctl config dbconsole -heap_size <size_value> -max_perm_size <size_value>
       emctl status agent
       emctl status agent -secure [-omsurl <http://<oms-hostname>:<oms-unsecure-port>/em/*>]
       emctl getversion
       emctl reload | upload | clearstate | getversion agent
       emctl reload agent dynamicproperties [<Target_name>:<Target_Type>]....
       emctl config agent <options>
       emctl config agent updateTZ
       emctl config agent getTZ
       emctl resetTZ agent
       emctl config agent credentials [<Target_name>[:<Target_Type>]]
       emctl gensudoprops
       emctl clearsudoprops
 Blackout Usage :
       emctl start blackout <Blackoutname> [-nodeLevel] [<Target_name>[:<Target_Type>]].... [-d <Duration>]
       emctl stop blackout <Blackoutname>
       emctl status blackout [<Target_name>[:<Target_Type>]]....