[FATAL BUG!] "back.sh" is extremely dangerous to run it in a system other than RPI or without a mounted RPI disk!

[HouWayne]

I here warn everyone who would like to use this tool": NEVER run it without a mounted RPI disk or in any other Linux which is not RPI! If so, all your mounted disks under /mnt will be wiped out

Terrible concequences when I did the stupid thing above

1. 4TB*2 disks are wiped out within 10 mins. Data recovery is still under process.
2. All my home directory is "backed up" to /mnt and exhausted all remaining space, preventing me from remote connection.

Lessons: NEVER generate destination for a "rsync --delete" script, always let human to pass-in their directories.

@nanhantianyi, please re-check your script and help me confirm what I guessed. Thanks.