Monitor bandwidth usage. This is a C version of the bandwidth blocklet.

It comes with some other features though:
make
[bandwidth]
command=$SCRIPT_DIR/bandwidth2
interval=persist
markup=pango
LABEL=
#INTERFACE=(checks all interfaces)
#USE_BITS=0
#USE_BYTES=1
#WARN_RX=0
#WARN_TX=0
#CRIT_RX=0
#CRIT_TX=0
#USE_SI=0
E.g.
[bandwidth]
command=$SCRIPT_DIR/bandwidth2
interval=persist
markup=pango
LABEL=
WARN_RX=307200
WARN_TX=30720
CRIT_RX=512000
CRIT_TX=51200