Tips and Tricks- 3

1. To find a process running in a port in linux

sudo netstat -lpn |grep :port_number
Eg:
sudo netstat -lpn |grep :9001
Sample Output:
tcp        0      0 :::9001                     :::*                        LISTEN      1070/java   

2. To kill a process running on a particular port in Linux

sudo kill -9 processid
Eg:
sudo kill -9 1070

3. Select varchar as timestamp in PostgreSQL

select to_timestamp(column_name, 'DD-MM-YYYY hh24:mi:ss') from table_name

4. Unzip a file in Linux

cd path_to_directory_containing_file
unzip file_name

5. Log of tomcat is found at

/tomcat/logs/catalina.out

6. Rename a table in postgreSQL

ALTER TABLE old_table_name RENAME TO new_table_name;

7. Disable logging in Java Xerces (“[Fatal Error] :1:1: Content is not allowed in prolog.”)

Setting the ErrorHandler to null suppresses the Fatal Error print line.

parser.setErrorHandler(null);
Eg:
DocumentBuilderFactory dBF = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = dBF.newDocumentBuilder();
builder.setErrorHandler(null);
Source: http://stackoverflow.com/questions/1575925/disable-logging-in-java-xerces-fatal-error-11-content-is-not-allowed-in-p

8. Display today's date in PostgreSQL

select now();

9. Extract hour from timestamp in PostgreSQL

select (extract(hour from to_timestamp(column_name, 'DD-MM-YYYY hh24:mi:ss'))) from table_name;

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