Gnuplot无效x范围，同时绘制温度随时间的变化

Question

我在格式

中有一个数据文件 cpuTemp.txt

09:16;314
09:19;314

并希望使用此脚本绘制此图：

#!/usr/bin/gnuplot
set datafile sep ';'                 # seperator ;
set terminal png                     #output format of graph
set term pngcairo size 300,300       #resolution
set output "temp.png"                #name of output file
set title "Temperature over Time"    #title of graph
set xlabel "time"                    #horizontal axis name
set ylabel "celsius * 10"            #vertical axis name
set timefmt "%H:%M"                  #format of time is source file cpuTemp.txt
set yrange [0:600]                   #vertical axis range (optional line)
set xdata time                       #x axis is not numbers, but dates/times
set format x "%H:%M"                 #format of time labels in axis label
set grid xtics lc rgb "#888888" lw 1 lt 0    #grey grid on background
set grid ytics lc rgb "#888888" lw 1 lt 0    #grey grid on background
plot "cpuTemp.txt" u 1:3 title "temperature" w lines lc rgb '#8b1a0e' lt 1 lw 2

现在执行时我得到了警告和这个我无法弄清楚的错误：

me@box:~ $ ./tempPlotter.sh 
"./tempPlotter.sh", line 15: warning: Skipping data file with no valid points

plot "cpuTemp.txt" using 1:3 title "temperature" with lines lc rgb '#8b1a0e' lt 1 lw 2
                                                                                      ^
"./tempPlotter.sh", line 15: x range is invalid

• ..为什么数据文件中没有有效点？
• ..为什么x范围无效？

提前致谢， Gewure