I tried the following
sudo cryptsetup luksChangekey /dev/nvme0n1p3 < new passphrase >
It then asks for the Sudo password, then asks for the old passphrase, but then it prints this error message
Failed to open key file.
what went wrong ?
Edit: turns out using GNOME Disks is way more straightforward.. 😅, thank you all
Alright so no permission issue, what if you run the changekey command in a separate bash subprocess?
sudo bash -c '($your-changekey-command-here)'
Is it like the same first "cryptsetup luksChangekey..." But inside parentheses ? Im sure I'm getting the syntax wrong.. It prints
bash: line 1: -luksChangekey: command not found