Cron 作业用于检测系统断电时间并返回无效时间

Question

我们的电气设备出了问题，所以我写了一个简单的 bash 脚本来记录事件发生的时间。我创建了一个 cron 作业，每分钟运行一次来​​运行该脚本。

该脚本的思路很简单，将时间戳写入 /tmp/powerlast.tmp。如果下次运行该脚本时，时间间隔大于 90 秒，则使用 $powerlast 值将条目附加到 powerfailure.csv 文件中。

我得到了一些奇怪的结果，例如在 12 月 24 日上午 11:50 电路跳闸，但脚本告诉我它发生在上午 11:20 - 这是错误的。

#!/bin/bash
powercsv=~/powerfailure.csv
powerlast=/tmp/powerlast.tmp
frequency=60                  # seconds
margin=$(($frequency+($frequency/2)))
if [ ! -f "$powercsv" ]; then
  echo "timestamp,weekofyear,dayofyear,day,date,month,year,hour,minute" > "$powercsv"
fi
if [ ! -f "$powerlast" ]; then
  echo "4133980799" > "$powerlast"
fi
last=$(($(cat "$powerlast"))) # seconds since epoch
now=$(($(date +%s)))          # seconds since epoch
lastdate=$(date -d @$last)
nowdate=$(date -d @$now)
if [ $now -lt $last ]; then
  # first run ever
  echo "$now" > "$powerlast"
else
  # aim is to detect gaps greater than the run frequency.
  # echo "margin $margin frequency $frequency"
  echo "$now" > "$powerlast"
  gap=$(($now-$last))
  if [ $gap -gt $margin ]; then
    echo "$nowdate: Power interruption detected at $lastdate! $gap exceeds $margin second limit."
    weekofyear=$(date -d @$last +%V)
    dayofyear=$(date -d @$last +%j)
    day=$(date -d @$last +%a)
    date=$(date -d @$last +%d)
    month=$(date -d @$last +%m)
    year=$(date -d @$last +%y)
    hour=$(date -d @$last +%H)
    minute=$(date -d @$last +%M)
    echo "$last,$weekofyear,$dayofyear,$day,$date,$month,$year,$hour,$minute" >> "$powercsv"
  fi
fi

我安排了一项任务* * * * * /home/usr/powerfailure/powerfailure.sh通过crontab -e

我检查了我用来跟踪上次正常运行时间的文件并且它似乎没有问题（我检查了我的时钟并且它是相同的）。

$ grep  -Eo '^[0-9]+' /tmp/powerlast.tmp | while read x; do date -d @$x; done
Tue Dec 24 12:41:02 GMT 2019

奇怪的是，我所有的条目似乎都记录了大约每小时 20 条。

$ grep -Eo '^[0-9]+' powerfailure.csv | while read x; do date -d @$x; done
Fri Dec 20 13:03:02 GMT 2019
Sat Dec 21 10:18:01 GMT 2019
Sat Dec 21 11:18:02 GMT 2019
Sat Dec 21 19:20:02 GMT 2019
Sun Dec 22 02:19:01 GMT 2019
Mon Dec 23 14:21:02 GMT 2019
Tue Dec 24 07:20:02 GMT 2019
Tue Dec 24 11:20:01 GMT 2019

我检查了 /var/log/syslog 并发现其中有一些奇怪的时间戳顺序，所以我认为这可能是罪魁祸首，但我不知道为什么会这样。

Dec 24 11:45:01 raspberrypi CRON[9915]: (usr) CMD (/home/usr/powerfailure/powerfailure.sh)
Dec 24 11:46:02 raspberrypi CRON[9976]: (usr) CMD (/home/usr/powerfailure/powerfailure.sh)
Dec 24 11:47:01 raspberrypi CRON[10011]: (usr) CMD (/home/usr/powerfailure/powerfailure.sh)
Dec 24 11:17:46 raspberrypi cron[324]: (CRON) INFO (pidfile fd = 3)
Dec 24 11:17:46 raspberrypi cron[324]: (pi) ORPHAN (no passwd entry)
Dec 24 11:17:46 raspberrypi cron[324]: (CRON) INFO (Running @reboot jobs)
Dec 24 11:18:01 raspberrypi CRON[737]: (usr) CMD (/home/usr/powerfailure/powerfailure.sh)
Dec 24 11:19:01 raspberrypi CRON[1459]: (usr) CMD (/home/usr/powerfailure/powerfailure.sh)
Dec 24 11:20:01 raspberrypi CRON[2308]: (usr) CMD (/home/usr/powerfailure/powerfailure.sh)
Dec 24 11:20:01 raspberrypi CRON[2313]: (smmsp) CMD (test -x /etc/init.d/sendmail && test -x /usr/share/sendmail/sendmail && test -x /usr/lib/sm.bin/sendmail && /usr/share/sendmail/sendmail cron-msp)
Dec 24 11:52:35 raspberrypi CRON[3237]: (usr) CMD (/home/usr/powerfailure/powerfailure.sh)
Dec 24 11:53:01 raspberrypi CRON[3657]: (usr) CMD (/home/usr/powerfailure/powerfailure.sh)
Dec 24 11:54:01 raspberrypi CRON[4600]: (usr) CMD (/home/usr/powerfailure/powerfailure.sh)

Answer 1

我把跟踪文件移出/tmp并修改了我的脚本来touch代替它。脚本现在跟踪文件的修改日期而不是内容。我仍然不清楚为什么它没有按预期工作，但这个系统完全按预期工作。

#!/bin/bash
powerdir=~/powerfailure
mkdir -p "$powerdir"
powercsv="$powerdir/powerfailure.csv"
powertouch="$powerdir/powerlast.touch"
frequency=60                  # seconds
margin=$(($frequency+($frequency/2)))
if [ ! -f "$powercsv" ]; then
  echo "timestamp,weekofyear,dayofyear,day,date,month,year,hour,minute" > "$powercsv"
fi
if [ ! -f "$powertouch" ]; then
  touch "$powertouch"
fi
last=$(date -r "$powertouch" +%s) # seconds since epoch
now=$(($(date +%s)))              # seconds since epoch
lastdate=$(date -d "@$last")
nowdate=$(date -d "@$now")
# echo "Last: $last, Now: $now, Last Date: $lastdate, Now Date: $nowdate"
if [ $now -lt $last ]; then
  # first run ever
  echo "$now" > "last"
  echo "Reset power last variable"
  echo "Reported: $(date)"
  echo "Last: '$last' -> $(date -d "@$last")"
  echo "Current: $now' -> $(date -d "@$now")"
else
  # aim is to detect gaps greater than the run frequency.
  # echo "margin $margin frequency $frequency"
  touch "$powertouch"
  gap=$(($now-$last))
  if [ $gap -gt $margin ]; then
    echo "Reported: $(date)"
    echo "Last: '$last' -> $(date -d "@$last")"
    echo "Current: '$now' -> $(date -d "@$now")"
    echo "$nowdate: Power interruption detected at $lastdate! $gap exceeds $margin second limit."
    weekofyear=$(date -d "@$last" +%V)
    dayofyear=$(date -d "@$last" +%j)
    day=$(date -d "@$last" +%a)
    date=$(date -d "@$last" +%d)
    month=$(date -d "@$last" +%m)
    year=$(date -d "@$last" +%y)
    hour=$(date -d "@$last" +%H)
    minute=$(date -d "@$last" +%M)
    echo "$last,$weekofyear,$dayofyear,$day,$date,$month,$year,$hour,$minute" >> "$powercsv"
  fi
fi