Ubuntu – How to merge partitions

partitioning

I have two partitions, one of them has a file system and the other is unallocated.

How to merge two partitions?

You can use gparted usc_logo for this. Also installable by sudo apt-get update && sudo apt-get install gparted

To make one big fresh partition (deletes all data on your filesystem):

First you'll have to make sure that both the partitions - unallocated space and the other partition to merge are either both logical partitions or both primary partitions. One logical and one primary will not work.
After checking and confirming the first step, delete the partition holding a filesystem.
Third, the unallocated space is now bigger since you have deleted a partition.
Create a partition of required size.

To increase the size of the partition holding data: (Although this is mostly safe, it's always wise to make a backup of your data!)

First you'll have to make sure that both the partitions - unallocated space and the other partition to merge are either both logical partitions or both primary partitions. One logical and one primary will not work.
Second, right-click on the partition in question and click resize. Fill in the size as required.
Click resize/move and then click Apply all operations

screenshot_gparted