Minor bug in freebsd-version(1), potential DoS vulnerability

Hi,

I discovered several bugs in `freebsd-version(1)`. Unfortunately, due to
Iran’s extended internet blackout I was unable to report them earlier and
now can only use a few whitelisted services (e.g., Gmail) to send this
message.

Bugs:
1. `-j` option handles arguments without quoting
   - The option expands variables without quotes, making it vulnerable to
glob expansion when special characters such as `?`, `*`, or `/` are
present.
   - Jails whose names contain spaces do not work because `freebsd-version`
iterates over a space‑separated list.
   - I could not run a jail with a space in its name, but I could run jails
containing `*` and `?`.
2. Information leakage and resource exhaustion
   - Carefully crafted input strings can reveal sensitive data or exhaust
system resources.

   Examples:
   # freebsd-version -j "/root/*"
   jexec: jail "/root/Book" not found

   # freebsd-version -j "/root/*/*/*/*"
   jexec: jail "/root/Book/Jung/C.G." not found

   # freebsd-version -j "/*/*/*/*/*/*/*/*/*"
   # (excessive expansion leading to high resource usage)

   - When provided with an empty string, the command exits silently:
   # freebsd-version -j ""

I have attached the patched script and a patchfile in this email. The
changes include:

- Adding quotation marks to the variable affected by the `-j` option.
- Setting `-f` to disable glob expansion.
- Minor styling improvements.
- A check for an empty `-j` option.

Please let me know what you think.

Thank you,
Nami Arj