Check empty output from fish function

Question

I have the following function that prints my current IP:

function get_ip
  echo -n -s (ifconfig en1 | grep inet | grep -v inet6 | awk '{print $2}')
end

$ get_ip
192.168.1.4~

I'm looking forward to print offline if get_ip returns nothing (it prints "" when I'm offline).

I tried:

if get_ip
  echo "Yes"
else
  echo "No"
end

But it always returns Yes.

How can I accomplish this?

Answer 1

You need to check the exit status of the test builtin.

if test -n (get_ip) 
    echo Yes
else
    echo No
end

---

While testing, I found some inconsistency between -n and -z that I will follow up on. Try this:

if test -z (get_ip) 
    echo No
else
    echo Yes
end

---

According to this answer from the fish maintainer, both answers are wrong, even though the 2nd one works. Use either

count (get_ip); and echo Y; or echo N

or

set result (get_ip)
test -n "$result"; and echo Y; or echo N