kbind is a command-line tool to execute commands quickly with a single keystroke.
kbind [statuscommand] <key>=<action>...
kbind ifconfig u='ifconfig eth0 up' d='ifconfig eth0 down'
This will call ifconfig in each iteration, as a command that displays the current status.
Whenever you type u into the console, the command ifconfig eth0 up will be
executed. Conversely, typing d will execute ifconfig eth0 down.
Implicit key bindings are q for quitting the program and for rerunning the status command.