1

我有一个运行每日 rsync 增量备份的 bash 脚本。

我的问题是我最终运行了多个实例。我是 bash 脚本的新手，所以我不确定我的脚本是否有问题？贴在下面。

但我读过有关 pid 锁定文件的信息？

谁能告诉我如何将它添加到我的脚本中？

#!/bin/bash
PATH=/usr/lib64/qt-     3.3/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin


LinkDest=/home/backup/files/backupdaily/monday

WeekDay=$(date +%A |tr [A-Z] [a-z])

echo "$WeekDay"

case $WeekDay in

    monday) 
    echo "Starting monday's backup"
    rsync -avz --delete --exclude backup --exclude virtual_machines /home  /home/backup/files/backupdaily/monday --log- file=/usr/local/src/backup/logs/backup_daily.log
        ;;

    tuesday|wednesday|thursday|friday|saturday)
    echo "Starting inc backup : $WeekDay"   
    rsync -avz --exclude backup --exclude virtual_machines --link-dest=$LinkDest /home     /home/backup/files/backupdaily/$WeekDay --log- file=/usr/local/src/backup/logs/backup_daily.log
        ;;

    sunday)    exit 0
        ;;
esac

所以看起来像这样？

#!/bin/bash
PATH=/usr/lib64/qt-    3.3/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

trap "rm -f /tmp/backup_daily_lockfile && exit" SIGINT SIGTERM #Put this on the top to   handle CTRL+C or SIGTERM

test -f /tmp/backup_daily_lockfile && exit #before rsync to ensure that the script will   not run if there is another one running

LinkDest=/home/backup/files/backupdaily/monday

WeekDay=$(date +%A |tr [A-Z] [a-z])

echo "$WeekDay"
touch /tmp/backup_daily_lockfile #Before the rsync
case $WeekDay in

monday) 
echo "Starting monday's backup"
rsync -avz --delete --exclude backup --exclude virtual_machines /home /home/backup/files/backupdaily/monday --log-file=/usr/local/src/backup/logs/backup_daily.log
    ;;

tuesday|wednesday|thursday|friday|saturday)
echo "Starting inc backup : $WeekDay"   
rsync -avz --exclude backup --exclude virtual_machines --link-dest=$LinkDest /home /home/backup/files/backupdaily/$WeekDay --log-file=/usr/local/src/backup/logs/backup_daily.log
        ;;

    sunday)    exit 0
        ;;

rm -f /tmp/backup_daily_lockfile #After the rsync

esac
4

2 回答 2

1

您提出的解决方案具有竞争条件。如果两个实例几乎同时运行，它们都可以test在其中任何一个到达touch. 然后他们最终会覆盖彼此的文件。

正确的解决方法是使用原子测试和设置。一个常见且简单的解决方案是使用临时目录，如果mkdir失败则退出；否则，你有锁。

# Try to grab lock; yield if unsuccessful
mkdir /tmp/backup_daily_lockdir || exit 1
# We have the lock; set up to remove on exit
trap "rmdir /tmp/backup_daily_lockdir" EXIT
# Also run exit trap if interrupted
trap 'exit 127' SIGINT SIGTERM

: the rest of your script here

还有其他常见的解决方案，但这没有外部依赖，非常容易实现和理解。

于 2014-05-21T13:24:23.347 回答
0

将以下内容添加到您的脚本中：

trap "rm -f /tmp/lockfile && exit" SIGINT SIGTERM #Put this on the top to handle CTRL+C or SIGTERM
test -f /tmp/lockfile && exit #Before rsync to ensure that the script will not run if there is another one running

touch /tmp/lockfile #Before the rsync

rm -f /tmp/lockfile #After the rsync

根据您的需要重命名锁文件路径/名称，您也可以使用 $$ 变量将其命名为当前 PID。

于 2014-05-21T12:37:15.683 回答