узнать текущую загрузку канала (eth0)

#!/bin/bash

IF=$1

#eth0 is a default if interface not specified
IF=${IF:=eth0}

     AWK=/usr/bin/awk
IFCONFIG=/sbin/ifconfig

SLEEP=5

first=( `$IFCONFIG $IF | $AWK '/RX bytes/ { split($2,a,":"); \
                              split($6,b,":");                   \
                                                  print a[2], b[2]}'` )

sleep $SLEEP

$IFCONFIG $IF | $AWK -v p=$SLEEP -v r=${first[0]} -v t=${first[1]} '/RX bytes/ \
       { split($2,a,":"); split($6,b,":"); \
          print "RX = "(a[2]-r)/p" B/s \t TX = "(b[2]-t)/p" B/s"}'


./if_speed.sh eth0
RX = 340467 B/s         TX = 443207 B/s