How to install VNC on Redhat and avoid getting "font catalog is not properly configured" error

 yum install -y  tigervnc-server tigervnc-server-module libXfont pixman xterm xorg-x11-twm

Setting YUM proxy settings in Redhat

If you are behind a proxy YUM won't be able to connect to its repositories. To fix this you will need to add your proxy setting to /etc/yum.conf

If you are using an anonymous proxy, only the following line needs to get added to yum.conf

proxy=http://<poxy-server>:<proxy-port>/

In case your proxy server requires authentication also add the following lines in addtion to the above

proxy_username=<proxy-user>
proxy_password=<proxy-password>

Determining schemas inside an Oracle data pump/dump file

Have you ever wondered how you can findout the schema or tablespace names contained within an Oracle Datapump dump or export?

Well, there is a way and it's an easy one:

First make sure ORACLE_SID and ORACLE_HOME is corectly set and Oracle binaries are in your PATH. Then using a user with appropriate privillages execute :

impdp \'/ as sysdba\' dumpfile=<YOUR_DMP_FILENAME>.dmp sqlfile=<OUTPUT_FILENAME>.txt

After this is done, simply open the text file for viewing and look for statements like :

CREATE USER ......

How to setup SSH private and public keys

• 1)
  % ssh-keygen -t rsa -b 4096 Generating public/private rsa key pair.
  Enter file in which to save the key (~/.ssh/id_dsa): (just press Enter) 
  Enter passphrase (empty for no passphrase): (enter a passphrase and then press Enter or if you don't want want one just press Enter) 
  Enter same passphrase again: (repeat last action) 
  Your identification has been saved in ~/.ssh/id_rsa
  Your public key has been saved in ~/.ssh/id_rsa.pub
  The key fingerprint is:
  A long string appears here
  %
• 2)
  Paste the content of the  ~/.ssh/id_dsa.pub file that just got generated on your local host into the file ~/.ssh/authorized_keys on the remote host and save.
• 3)
  Set proper permissions on your local host keys and .ssh directory:
  chmod 700 ~/.ssh
  chmod 644 ~/.ssh/id_rsa.pub
  chmod 600 ~/.ssh/id_rsa
  set proper permissions on your remote host authorized_keys and .ssh directory
  chmod 700 ~/.ssh
  chmod 644 ~/.ssh/authorized_keys
  

How to find the 10 largest file or directories in Linux

This finds the largest 10 files :

find . -type f -print0 | xargs -0 du -s | sort -n | tail -10 | cut -f2 | xargs -I{} du -sh {}

This finds the largest 10 directories:

find . -type d -print0 | xargs -0 du -s | sort -n | tail -10 | cut -f2 | xargs -I{} du -sh {}

You can easily change -10 to -n where n is the number of files/directories you are trying to find.