I have installed wireshark on Ubuntu, When I run it:
/usr/bin/wireshark
I get an error:
(wireshark:27945): Gtk-WARNING **: cannot open display:
I want to run wireshark on the command prompt.
I don't want to use the UI. I'm not sure why it is complaining about a display, I want to run it on a port.
You can try tshark - which is a "console based wireshark" which is part of wireshark project.
You should read Read man tshark.
For example to capture http packet on 80 port run:
tshark -f 'tcp port 80 and http'
P.S. Example was fixed to use capture filter instead of display filter.