Why Isn’t My Bash File Descriptor Closing After the First Read?

The programming manual states that if `{varname}` is provided, the redirection can persist, which allows for better control over the file descriptor's lifetime without needing `exec`. You might be observing behavior based on that, but I can't verify it without having a machine to test on right now.

It looks like your code formatting might be a bit tricky for some platforms. If possible, try not to use inline code blocks when posting bash code. Just add four spaces at the beginning of each line to make it clearer.

Regarding your issue, you can't close a file descriptor in the way you're attempting. You would need to explicitly execute `exec {fd}<&-` to close it. Otherwise, it just gets moved to the standard input.

According to the bash man page, when using `exec`, the redirections affect the file handles in the current shell session. However, if you use `mycommand {fd}<-`, it can close the file descriptor. But, if you're working with processes forked from that command, the closures might not behave as you expect. The confusion often arises with builtin commands like `read` that don't follow the same rules as external commands.