June 2016

Steps to load iptable rules automatically on Ubuntu Linux using package iptables-persistent. Install iptables-persistent $ sudo apt-get install iptables-persistent When asked during installation should it read more

Print exception stack trace Print exception short description

Java String startsWith(String prefix) example: To specify offset use startsWith(String prefix, int toffset)

Java – two dimentional array example

Fill all values in an array Fill range in an array

To print Java (JVM) home path on command line the following command (jave_home) can be used as shown below: $ /usr/libexec/java_home /Library/Java/JavaVirtualMachines/jdk1.7.0_65.jdk/Contents/Home To display all read more

To remove passphrase from an existing key, we can use ssh-keygen with -p option. Here is an example which changes passphrase of private rsa key read more

To check if an ssh key has passphrase, one can look for the presence of ENCRYPTED string in the private key. Here is an example read more

Netcat (nc) can be use to check if a remote port is reachable and client can connect to it. The following commands were tried on read more

System.out.format method format multiple arguments based on format string. Basic example print integer 8 characters in width print float with 2 digits after decimal point

System.out.println example println will append a new line after the string. System.out.print example print will not append a new line after the string.

String method equals check if both references points objects with same values stored in them. Operator == check if both references points to same object.

Initialize arrat and print length Access element at specific index Access non existing index This will throw Index Out Of Bounds Exception

When using a bastion host (or Jumpbox) to connection to production server using ssh private keys, ssh agent forward can be used. The main advantage read more

Case sensitive comparison Compare strings using firstString.compareTo(secondString). Positive outcome means firstString > secondString and so on. Case insensitive comparison – compareToIgnoreCase

Initialize string array using curly braces {}

Sometimes it is useful to find what ports a machine is listening to. Here are some use cases: Display listening ports $ netstat -l Display read more

Steps to enable mysql query log on mysql server without restarting mysql process on Ubuntu and other Linux flavours. Set general_log_file on SQL prompt: SET read more

Chrome developer tools has a pretty handy feature to copy any GET/POST request in network tab to cURL. This also copies all headers involved in read more

Mac desktop icons size can be increased or decreased using Desktop view options. There are steps: Click anywhere on blank Desktop area. Click on View read more