mac os x disk mount

Catalina now has restrictions for various applications. You will have to do the following first.

1. go to System Preferences->Security&Privacy->Privacy->Full Disk Access
2. unlock settings (click on lock icon in the left bottom corner and enter password)
3. click on + button and select iTerm.app application
4. restart iTerm.app and try the mount process again

For some reason, now I can only use the sudo to mount a disk

sudo mount -t hfs /dev/disk2s2 /Volumes/tongbackup

I have to create the mount point (/Volumes/tongbackup) first

I did not have to do that before.

For msdos fat file system, do the following.

First Unmount:

sudo diskutil unmount /dev/disk3s1

Then Mount again:

This mount the msdos file type

sudo mount -w -t msdos /dev/disk3s1 /Volumes/$NAME

or

This mount the exfat file type

sudo mount -w -t exfat /dev/disk3s1 /Volume/$NAME 

Then you can write to it.