This question already has an answer here:

I have a 1 TB hard drive and all of it is occupied by a Linux partition (minus 512 MB for /boot/efi).

Now I want to split this partition in two halves for installing another OS. This answer tells me it’s impossible. But is there really no other way to do it without using a Live CD or an external hard drive?

Current OS: Ubuntu 18.04

marked as duplicate by David Foerster, karel, Fabby, Eric Carvalho, N0rbert Sep 13 '18 at 21:03

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • I do not know a way with standard partitioning. You probably should have a flash drive or DVD with the current installed version of Ubuntu anyway, as it may be needed for repairs in future. – oldfred Sep 11 '18 at 20:48
  • Most filesystems can't be resized whilst in use, so you need to umount first most likely. If your file system is / it will contain the umount command, meaning the moment you've run it, you've likely lost access to your gparted utility etc. With skill yes you can do it, but it's far easier to use a 'live' system where those needed tools aren't on a partition you want to re-size. Because you're asking how - you won't be skilled enough in my opinion to do it, and really should be using a 'live' system where mistakes are less likely, and less costly (even if it's just in time/stress). – guiverc Sep 11 '18 at 21:47
  • Welcome to Ask Ubuntu! I don’t see any notion in the linked answer that this task is impossible. How did you reach that conclusion? Have you looked at or tried the other answers to the same question? – David Foerster Sep 12 '18 at 8:39
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    Possible duplicate of How can I resize an ext root partition at runtime? or more generally, easily and safely How to resize partitions? – David Foerster Sep 12 '18 at 8:39