I understand you. I'm sure this problem is not too difficult to solve.
In an interactive session where I could run commands, it would have been faster.

If you have enough time, I would suggest taking some Linux course on your own.

You have changed to Linux Mint.
As root:

Get the uid=? and gid=? values from the previous command and replace it in the next command.

As root, post the results here:

I guess you have rebooted the machine and the external hard disk was not remount correctly before running touch, or maybe, your UID is not 999 now, getting forbidden permissions error.

The more things you post details about, the better for me and other users to solve your problem.

Without a defining killer app, I am confident that Bitcoin will, in fits and starts, inevitably return to its 2009 levels. It would be pointless to guess how long that process will take; or when that killer app will appear although I am also confident it will appear at some entirely unpredictable point.

I'm easily old enough to remember the very early days of personal computers. I remember a story from The Wall Street Journal in which a reporter interviewed a small-business owner (I think an auto-repair shop) who had bought an Apple II. The reporter asked the man what he thought of his purchase. The man stared glumly at the Apple for a moment and then sourly commented: "The damn thing just sits there."

Exactly. The world was just never going to buy into a command-prompt environment in a really big way. But the Mac came along and then the world began to change. (Be like the Mac! Bill Gates commanded his troops developing Windows 95.) And so it will be with Bitcoin. The world will never buy into it until an environment comes along that makes it easier, safer, and a lot more fun to use. Until then, the price will suffer periodic whale-dumps and then sort of bounce, spurt, and finally just roll along long enough for people to start talking (again) about "Bitcoin's recent price stability." And then yet another whale-dump will splash the water and the retroactively obvious cycle will begin again.

That actually means success

You should be about to rerun "mount" without any arguments to see that /dev/sdb1 is mounted on /cdrom rw.

Cheers!

EDIT: for your own education, in general UNIX command return 0 upon success.  The return code from the last command is stored in your shell as $?.  If you say "echo $?" you can see the return code of the previous command.

I haven't used Linux Mint, but I understand that it's still downstream of debian.  In any case, certainly things like mounting drives and reading/writing from them is going to be the same.

On topic, you said the command was unsuccessful, can you cut-n-paste the exact response from the shell?

mint@mint ~ $ sudo su
mint mint # mount -o remount,rw,uid=999,gid=999 /dev/sdb1 /cdrom
mint mint # 

Did you try:

If that command is successful, post ls -al command result and try to create a file in /cdrom as a regular user: echo testing > /cdrom/permissions-test.txt

Post the result of command (run as a regular user): id

uid=999(ubuntu) gid=999(ubuntu) groups=999(ubuntu),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),115(lpadmin),131(sambashare)