'vnstat' works, 'vnstat -l' doesn't

Question

I have just installed vnstat. I run vnstat and get this:

~$ vnstat

                  rx      /      tx      /     total    /   estimated
wlan0:
   Aug '12     12.89 MiB  /   14.14 MiB  /   27.03 MiB  /   37.00 MiB
     today     12.89 MiB  /   14.14 MiB  /   27.03 MiB  /      29 MiB

irda0: Not enough data available yet.
eth0: Not enough data available yet.

I'm only using wireless, and I've only just installed it, so I would expect that. However, when I run vnstat -l, it only returns stuff for eth0; wlan0 isn't present:

~$ vnstat -l
Monitoring eth0...    (press CTRL-C to stop)

   rx:        0 kbit/s     0 p/s          tx:        0 kbit/s     0 p/s^C

Similarly when I run vnstat -h (show traffic for last 24 hours), or any one of a number of other commands, it only complains about not having enough data for eth0, and doesn't try to return anything for wlan0. What's going on?

Answer 1

Turns out a lot of the vnstat switches only work with the default interface (in my case eth0) unless another is specified.

Specify an interface with -i, like vnstat -h -i wlan0. You can get a list of available interfaces using ifconfig.

Default interface can be specified in the config (probably in /etc/vnstat.conf).