SD card formating

In Disk Utility.app:

• Select the card.
• At the bottom of the window, it should show Write Status: followed by some words.
• If it says Read Only after Write Status, then the write-protect switch is active (or whatever you're using to read the card is mistakenly asserting write-protect).

If you don't see Write Status at all, you've probably selected the volume on the card. Try again with the enclosing item.

There's nothing you can do with Terminal that can't be done more simply and more safely with Disk Utility.app. And if the card isn't writable, there's nothing you can do about it in Terminal.

If you want something safe and useful for Terminal, copy and paste this into a Terminal window:
Then copy and paste the output into a post.

The permissions will show whether the disk device is writable or not. You can't change them, but at least it should reflect what Write Status in Disk Utility.app is showing.