Ubuntu : Level 1 : Post 4.1 : More about Shell Scripting in Linux Ubuntu

In this we will learn other things about shell-scripting Shortcuts in bash: history: Command that shows you previous commands that you have typed in this shell. Use ! to execute a command corresponding to a number. Ctrl-r: Searches for a command in history. When found, just press Enter to execute it. Ctrl-p: Go to the previous… Read More »

MongoDB : Post 9 : Specific query operators : $exists

$exists : $exists operator , when true , $exists matches the documents that contain the field.It also includes the documents where the field value is ‘null’.When false, the query returns only the documents that do not contain the field.The example with various operators will give a better picture : Example 1 : The following query selects… Read More »