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Bash 脚本：仅询问一次 sudo 密码

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Bash 脚本：仅询问一次 sudo 密码

我正在编写一个备份 bash 脚本，它可以执行许多耗时较长的rsync任务。有些任务每次最多需要 3 到 4 个小时。

在这些大型传输之后，我希望在同步文件后刷新磁盘缓存，然后在目标磁盘上运行一些校验和，以确保目标磁盘上的所有内容都已备份好。下面这行代码据说可以做到这一点，需要sudo：

sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches'

为了不间断地完成整个 bash 脚本，我在开始时要求输入用户密码sudo，但我注意到sudo可以理解的是，密码会话仅持续了 15 分钟左右。几个小时后，脚本停止等待用户sudo再次输入密码。

运行此脚本的最佳方法是什么，以sudo在需要时保留权限，但无需每次都请求密码，以便脚本可以不间断地运行几个小时，并保留磁盘缓存刷新命令的能力？

#!/bin/bash

# backup all drives using rsync and also verify the integrity of the backup

    # BACKUP

    # first, drop the disks internal volatile caches to start with clean file system state (https://unix.stackexchange.com/questions/30970/)
    printf "\nNeed sudo priviliges in order to flush disk caches in this script.\n"
    # invoke sudo to ask for permission needed to clear the disk cache in next command
    sudo printf "\nClearing disk cache... " 
        sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches'
    printf "DONE.\n\n\n"

    # now run the backup lines
        # First disk
        printf "rsync 'First' disk...\n"
        # need to put [] around $ to escape it for folders like $RECYCLE.BIN (https://stackoverflow.com/questions/19305010)
        rsync -vah --progress --stats --exclude={"Adobe","[$]RECYCLE.BIN","System Volume Information","pagefile.sys","temp"} /media/n/First/ ./First/
        printf "\n\n"

        # Scratch disk
        printf "rsync 'Scratch' disk...\n"
        rsync -vah --progress --stats --exclude={"[$]RECYCLE.BIN","System Volume Information","pagefile.sys","temp"} /media/n/Scratch/ ./Scratch/
        printf "\n\n"


        # ...



    # CHECKSUM
    # re-read/compare

    # drop the disks internal volatile caches
    printf "Now testing backup checksums for integrity.\n\n"
    # rsync --itemize-changes, legend here: (https://stackoverflow.com/questions/4493525)

        # First disk
        printf "Clearing disk cache... "
            sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches'
        printf "DONE.\n"
        printf "Checking 'First' disk backup...\n"
        # need to put [] around $ to escape it for folders like $RECYCLE.BIN (https://stackoverflow.com/questions/19305010)
        rsync -vah --progress --checksum --itemize-changes --stats --exclude={"Adobe","[$]RECYCLE.BIN","System Volume Information","pagefile.sys","temp"} /media/n/First/ ./First/
        printf "\n\n"


# ...



print "Finished.\n\n"

# revoke sudo
sudo -k
exit

答案1

使用 sudo 运行你的脚本。

sudo yourscript.sh

只需询问您一次，脚本就会以 root 权限运行。

答案2

使用（以 root 身份）visudo（或直接编辑 /etc/sudoers）并添加：

# below "root ALL=..."
jonny      ALL=NOPASSWD: your_script

注意：该脚本必须位于 /etc/sudoers 中的“secure_path”之一中

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