drop down structure in file

Shell Programming and Scripting
1

I have file like this

120, rahim, d40
115, rahul, d40
113, begum, d40

I want to group this file like this

120, rahim, d40
115, rahul,
113, begum,

can any one help me on this

thanks in advance

2

You can do this easily in awk. Just save the value of the last field in a variable, and if it is still the same when you read the next line, do not print the last field.