group by 'last' value in bash

Question

I have a two-column file:

1,112
1,123
2,123
2,124
2,144
3,158
4,123
4,158
5,123

I need to know last column2 value for each column1:

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Answer 1

This is pretty similar to @Sundeep's solution but here it goes:

$ tac file|uniq -w 1|tac
1,123
2,144
3,158
4,158
5,123

ie. reverse the record order with cat, uniq outputs based on the first character only and then the order is reversed again.