Expand Linux Partition to new size

EXT4 filesystem supports online (that's, without unmounting) resizing with resize2fs command.
First, you had to resize the partition itself with partition editor (parted):

Parted/dev/sdb

GNU Parted 2.3
Using/dev/sdb
Welcome to GNU parted! Type ' help ' to view a list of commands.
(parted) p
Model:vmware Virtual disk (SCSI)
Disk/dev/sdb:5498gb
Sector size (logical/physical): 512b/512b
Partition TABLE:GPT

Number Start End Size File system Name Flags
1 1049kB 3298GB 3298GB ext4

Now, use Resizepart command and give partition number as it parameter (in our case, 1). When asked for new size, enter-1 (means with all space up to the last available sector on disk):

(parted) Resizepart 1
PARTITION/DEV/SDB1 is being used. Is you sure want to continue?
Yes/no? Y
End? [3298GB]? -1
(parted) Q
Information:you need to Update/etc/fstab.

Now you can call the RESIZE2FS command. No need to input anything, it'll automatically grow the filesystem to the new partition size:

Resize2fs-p/DEV/SDB1

Expand Linux Partition to new size