通用性较差呢，用于rrd绘图

graph.sh

#!/bin/bash
name="gateway"
declare -a temp_arr
def="DEF:rrd_rtt=$name.rrd:rtt:AVERAGE \
    DEF:rrd_pl=$name.rrd:pl:AVERAGE \
    VDEF:rtt_max=rrd_rtt,MAXIMUM \
    VDEF:pl_max=rrd_pl,MAXIMUM \
    -e now -s end-2h \
"
NUM="`rrdtool graph xxx \
    $def \
    PRINT:pl_max:""%3.6lf"" \
    PRINT:rtt_max:""%5.6lf""
`"
temp_arr=($NUM)
bili=`echo "${temp_arr[1]} / ${temp_arr[2]}"|bc -l`
[ ${bili:=0} = 0 ] && bili=1

rrdtool graph - \
    $def \
    --right-axis $bili:0 \
    --right-axis-format "%3.3lf%%" \
    CDEF:view_pl=rrd_pl,$bili,/ \
    AREA:view_pl#baf:"Packet loss (%)" \
    COMMENT:"cur/avg/min/max=(\g" \
    GPRINT:rrd_pl:LAST:"%3.3lf/\g" \
    GPRINT:rrd_pl:AVERAGE:"%3.3lf/\g" \
    GPRINT:rrd_pl:MIN:"%3.3lf/\g" \
    GPRINT:rrd_pl:MAX:"%3.3lf\g" \
    COMMENT:")%\n" \
    LINE:rrd_rtt#000:"Rtt (ms)" \
    COMMENT:"cur/avg/min/max=(\g" \
    GPRINT:rrd_rtt:LAST:"%3.3lf/\g" \
    GPRINT:rrd_rtt:AVERAGE:"%3.3lf/\g" \
    GPRINT:rrd_rtt:MIN:"%3.3lf/\g" \
    GPRINT:rrd_rtt:MAX:"%3.3lf\g" \
    COMMENT:")ms\n" \
    COMMENT:"test pl_max rtt_max bili" \
    COMMENT:"${temp_arr[1]}" \
    COMMENT:"${temp_arr[2]}" \
    COMMENT:"$bili" \
    COMMENT:"\n" \
    -t $name \
    -v "Round-trip delay time (ms)" \
    --right-axis-label "Packet loss (%)" \
    -W "`date`" \
    -w 576 -h 200 \
    -l 0 -r -X b