仅当文件系统已挂载时才进行 RSync

StackOverflow https://stackoverflow.com/questions/27359

  •  09-06-2019
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题

我想设置一个 cron 作业来将远程系统同步到备份分区，例如：

bash -c 'rsync -avz --delete --exclude=proc --exclude=sys root@remote1:/ /mnt/remote1/'

我希望能够“设置它并忘记它”，但是如果 /mnt/remote1 变得卸载？（重新启动或其他操作后）如果出现以下情况，我想出错 /mnt/remote1 未安装，而不是填充本地文件系统。

编辑：
这是我想出的脚本，清理改进值得赞赏（特别是对于空的然后......否则，我不能将它们留空或 bash 错误）

#!/bin/bash

DATA=data
ERROR="0"

if cut -d' ' -f2 /proc/mounts | grep -q "^/mnt/$1\$"; then
    ERROR=0
else
    if mount /dev/vg/$1 /mnt/$1; then
        ERROR=0
    else
        ERROR=$?
        echo "Can't backup $1, /mnt/$1 could not be mounted: $ERROR"
    fi
fi

if [ "$ERROR" = "0" ]; then
    if cut -d' ' -f2 /proc/mounts | grep -q "^/mnt/$1/$DATA\$"; then
        ERROR=0
    else
        if mount /dev/vg/$1$DATA /mnt/$1/data; then
            ERROR=0
        else
            ERROR=$?
            echo "Can't backup $1, /mnt/$1/data could not be mounted."
        fi
    fi
fi

if [ "$ERROR" = "0" ]; then
    rsync -aqz --delete --numeric-ids --exclude=proc --exclude=sys \
        root@$1.domain:/ /mnt/$1/
    RETVAL=$?
    echo "Backup of $1 completed, return value of rsync: $RETVAL"
fi
有帮助吗？

解决方案 

if cut -d' ' -f2 /proc/mounts | grep '^/mnt/remote1$' >/dev/null; then
    rsync -avz ...
fi

获取已挂载的分区列表 /proc/mounts, 只匹配 /mnt/remote1 （如果已安装，请将 grep 的输出发送到 /dev/null），然后运行你的 rsync 工作。

最近的 greps 有一个 -q 您可以使用该选项而不是将输出发送到 /dev/null.

其他提示

mountpoint 似乎是最好的解决方案：如果路径是挂载点，则返回 0：

#!/bin/bash
if [[ `mountpoint -q /path` ]]; then
    echo "filesystem mounted"
else
    echo "filesystem not mounted"
fi

发现于 Linux问题.

快速谷歌让我找到了这个 bash 脚本，它可以检查文件系统是否已安装。看来 grep df 或 mount 的输出是正确的方法：

if df |grep -q '/mnt/mountpoint$'
    then
        echo "Found mount point, running task"
        # Do some stuff
    else
        echo "Aborted because the disk is not mounted"
        # Do some error correcting stuff
        exit -1
fi
  1. 将下面的脚本复制并粘贴到文件中（例如备份.sh）。
  2. 使脚本可执行（例如 chmod +x backup.sh)
  3. 使用以下格式以 root 身份调用脚本 backup.sh [username (for rsync)] [backup source device] [backup source location] [backup target device] [backup target location]

！！！注意力！！！在不理解代码的情况下，不要以 root 用户身份执行脚本！

我觉得没什么好解释的该代码简单明了并且有详细的文档记录。

#!/bin/bash

##
## COMMAND USAGE: backup.sh [username] [backup source device] [backup source location] [backup target device] [backup target location]
##
## for example: sudo /home/manu/bin/backup.sh "manu" "/media/disk1" "/media/disk1/." "/media/disk2" "/media/disk2"
##

##
## VARIABLES
##

# execute as user
USER="$1"

# Set source location
BACKUP_SOURCE_DEV="$2"
BACKUP_SOURCE="$3"

# Set target location
BACKUP_TARGET_DEV="$4"
BACKUP_TARGET="$5"

# Log file
LOG_FILE="/var/log/backup_script.log"

##
## SCRIPT
##

function end() {
    echo -e "###########################################################################\
#########################################################################\n\n" >> "$LOG_FILE"
    exit $1
}

# Check that the log file exists
if [ ! -e "$LOG_FILE" ]; then
        touch "$LOG_FILE"
    chown $USER "$LOG_FILE"
fi

# Check if backup source device is mounted
if ! mountpoint "$BACKUP_SOURCE_DEV"; then
        echo "$(date "+%Y-%m-%d %k:%M:%S") - ERROR: Backup source device is not mounted!" >> "$LOG_FILE"
    end 1
fi

# Check that source dir exists and is readable.
if [ ! -r  "$BACKUP_SOURCE" ]; then
        echo "$(date "+%Y-%m-%d %k:%M:%S") - ERROR: Unable to read source dir." >> "$LOG_FILE"
        echo "$(date "+%Y-%m-%d %k:%M:%S") - ERROR: Unable to sync." >> "$LOG_FILE"
    end 1
fi

# Check that target dir exists and is writable.
if [ ! -w  "$BACKUP_TARGET" ]; then
        echo "$(date "+%Y-%m-%d %k:%M:%S") - ERROR: Unable to write to target dir." >> "$LOG_FILE"
        echo "$(date "+%Y-%m-%d %k:%M:%S") - ERROR: Unable to sync." >> "$LOG_FILE"
    end 1
fi

# Check if the drive is mounted
if ! mountpoint "$BACKUP_TARGET_DEV"; then
        echo "$(date "+%Y-%m-%d %k:%M:%S") - WARNING: Backup device needs mounting!" >> "$LOG_FILE"

        # If not, mount the drive
        if mount "$BACKUP_TARGET_DEV" > /dev/null 2>&1 || /bin/false; then
                echo "$(date "+%Y-%m-%d %k:%M:%S") - Backup device mounted." >> "$LOG_FILE"
        else
                echo "$(date "+%Y-%m-%d %k:%M:%S") - ERROR: Unable to mount backup device." >> "$LOG_FILE"
                echo "$(date "+%Y-%m-%d %k:%M:%S") - ERROR: Unable to sync." >> "$LOG_FILE"
        end 1
        fi
fi

# Start entry in the log
echo "$(date "+%Y-%m-%d %k:%M:%S") - Sync started." >> "$LOG_FILE"

# Start sync
su -c "rsync -ayhEAX --progress --delete-after --inplace --compress-level=0 --log-file=\"$LOG_FILE\" \"$BACKUP_SOURCE\" \"$BACKUP_TARGET\"" $USER
echo "" >> "$LOG_FILE"

# Unmount the drive so it does not accidentally get damaged or wiped
if umount "$BACKUP_TARGET_DEV" > /dev/null 2>&1 || /bin/false; then
    echo "$(date "+%Y-%m-%d %k:%M:%S") - Backup device unmounted." >> "$LOG_FILE"
else
    echo "$(date "+%Y-%m-%d %k:%M:%S") - WARNING: Backup device could not be unmounted." >> "$LOG_FILE"
fi

# Exit successfully
end 0

我正在浏览此内容，但我认为您更愿意 rsync -e ssh 并设置密钥来接受帐户。

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