Question

我正在尝试编写一个记录连接状态的脚本，并作为cron作业运行。如果它获得了ip，它会将时间记录到文件中。

#!/bin/bash

ip=$(wget htt://checkip.dyndns.org/ -q -O - |
grep -Eo '\<[[:digit:]]{1,3}(\.[[:digit:]]{1,3}){3}\>')

echo $ip

if [ -n "$ip" ]
then
    echo 'connected:'$(date +"%d-%m-%Y %I:%M") >> /home/saad/offline_check
else
    echo 'disconnected:'$(date +"%d-%m-%Y %I:%M") >> /home/saad/offline_check
fi

此脚本将每隔5分钟将connected:XXXX附加到文件中。我希望它写一次＆amp;然后在发生断开连接之前不再进行日志记录。当连接恢复时，它应该将当前连接时间写在新行上。

这就是我想要的：

connected:08-02-2014 08:30     #start, all connected timestamps after initial one ignored
disconnected:09-02-2014 08:35  #disconnection logged
connected:09-02-2014 17:31     #when connection resumes, timestamp logged, all subsequent ignored until disconnect
disconnected:11-02-2014 08:31

我可以在python中执行此操作，但不能在bash中执行此操作。

Answer 1

您可以在写入之前检查最后一行日志文件：

#!/bin/bash

ip=$(wget htt://checkip.dyndns.org/ -q -O - |
grep -Eo '\<[[:digit:]]{1,3}(\.[[:digit:]]{1,3}){3}\>')

# get the last line from log
line=$(tail -1 /home/saad/offline_check)

echo $ip

if [ -n "$ip" ]; then
    # if last line starts with "disconnected" OR is empty then write "connected" log
    [[ -z "$line" || "$line" == 'disconnected:'* ]] && \
            echo 'connected:'$(date +"%d-%m-%Y %I:%M") >> /home/saad/offline_check
else
    [[ "$line" == 'connected:'* ]] && echo 'disconnected:'$(date +"%d-%m-%Y %I:%M") >> /home/saad/offline_check
fi

基于标准的bash脚本行替换

1 个答案: