Question

I often have trouble figuring out certain language constructs because they won’t register when googling or duckduckgoing them. With a bit of experimenting, it’s often simple to figure it out, but I don’t get this one.

I often see stuff like 2>&1 or 3>&- in bash scripts. I know this is some kind of redirection. 1 is stdout and 2 is stderror. 3 is probably custom. But what is the minus?

Also, I have a script whose output I want to log, but also want to see on screen. I use exec > >(tee $LOGFILE); exec 2>&1 for that. It works. But sometimes when I bashtrap this script, I cannot type at the prompt anymore. Output is hidden after Ctrl+C. Can I use a custom channel and the minus sign to fix this, or is it unrelated?

Answer 1

1. 2>&1 means that stderr is redirected to stdout
2. 3>&- means that file descriptor 3, opened for writing(same as stdout), is closed.

You can see more examples of redirection here

3. As for questions number 3, I think this is a good link.