Hello! I have a /home partition that is almost full, and there is another partition nearby with a lot of free space. I would like to reduce the size of this neighboring partition and add the freed space to /home. I would like to do this safely, without using a Live USB or bootable flash drive. Is this possible?
Use cfdisk and just edit the partitions.
Please note that if you do this without first resizing the filesystems on the partitions, you are very likely to lose data. You cannot safely shrink a mounted partition.
Edit: oh you mean booted from external media, not an online system. Use gparted. https://gparted.org/