Reformatting the exfat external hard drive for Linux backup
The Linux system has files formatted ext4.
$sudo fdisk -l
gave /dev/sdb1 as the external drive name.
I ran the following with the device unmounted:
sudo mkfs -v -t ext4 -l wdext /dev/sdb1
to name the device wdext, and give it the ext4 format structure.
Then I set device ownership:
chmod 777 /media/wdext
Then I am set to backup files.
Thanks for the comments.