`udevadm test` 显示命令应该在 USB 磁盘上运行，但实际上却没有

2024-6-4 • tag-icon

`udevadm test` 显示命令应该在 USB 磁盘上运行，但实际上却没有

我希望在安装某些外部 USB 驱动器时执行备份脚本。我正在尝试使用 udev 实现此目的。

我目前所做的：

使用识别了我的 USB 驱动器sudo udevadm info --attribute-walk --name /dev/sda，其输出为：

  looking at device '/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2.3/1-5.2.3:1.0/host0/target0:0:0/0:0:0:0/block/sda':
    KERNEL=="sda"
    SUBSYSTEM=="block"
    DRIVER==""
    ATTR{size}=="1953525168"
    ATTR{events_async}==""
    ATTR{ext_range}=="256"
    ATTR{range}=="16"
    ATTR{inflight}=="       0        0"
    ATTR{hidden}=="0"
    ATTR{ro}=="0"
    ATTR{discard_alignment}=="0"
    ATTR{alignment_offset}=="0"
    ATTR{capability}=="50"
    ATTR{events_poll_msecs}=="-1"
    ATTR{removable}=="0"
    ATTR{events}==""
    ATTR{stat}=="     445     7963    19565     3971        7        1       64       21        0     1036     3204        0        0        0        0"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2.3/1-5.2.3:1.0/host0/target0:0:0/0:0:0:0':
    KERNELS=="0:0:0:0"
    SUBSYSTEMS=="scsi"
    DRIVERS=="sd"
    ATTRS{state}=="running"
    ATTRS{inquiry}==""
    ATTRS{evt_inquiry_change_reported}=="0"
    ATTRS{evt_capacity_change_reported}=="0"
    ATTRS{device_busy}=="0"
    ATTRS{evt_mode_parameter_change_reported}=="0"
    ATTRS{evt_lun_change_reported}=="0"
    ATTRS{ioerr_cnt}=="0xc"
    ATTRS{iocounterbits}=="32"
    ATTRS{eh_timeout}=="10"
    ATTRS{vendor}=="ST310005"
    ATTRS{queue_depth}=="1"
    ATTRS{device_blocked}=="0"
    ATTRS{blacklist}==""
    ATTRS{evt_media_change}=="0"
    ATTRS{scsi_level}=="3"
    ATTRS{evt_soft_threshold_reached}=="0"
    ATTRS{iodone_cnt}=="0x1f8"
    ATTRS{queue_type}=="none"
    ATTRS{timeout}=="30"
    ATTRS{model}=="20AS            "
    ATTRS{max_sectors}=="240"
    ATTRS{iorequest_cnt}=="0x1f8"
    ATTRS{type}=="0"
    ATTRS{rev}=="    "
    ATTRS{dh_state}=="detached"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2.3/1-5.2.3:1.0/host0/target0:0:0':
    KERNELS=="target0:0:0"
    SUBSYSTEMS=="scsi"
    DRIVERS==""

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2.3/1-5.2.3:1.0/host0':
    KERNELS=="host0"
    SUBSYSTEMS=="scsi"
    DRIVERS==""

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2.3/1-5.2.3:1.0':
    KERNELS=="1-5.2.3:1.0"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb-storage"
    ATTRS{bNumEndpoints}=="02"
    ATTRS{supports_autosuspend}=="1"
    ATTRS{bInterfaceNumber}=="00"
    ATTRS{bInterfaceClass}=="08"
    ATTRS{interface}=="MSC Bulk-Only Transfer"
    ATTRS{bInterfaceProtocol}=="50"
    ATTRS{authorized}=="1"
    ATTRS{bAlternateSetting}==" 0"
    ATTRS{bInterfaceSubClass}=="06"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2.3':
    KERNELS=="1-5.2.3"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{maxchild}=="0"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{authorized}=="1"
    ATTRS{tx_lanes}=="1"
    ATTRS{manufacturer}=="Lomega"
    ATTRS{serial}=="50F26FFFFFFF"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{devpath}=="5.2.3"
    ATTRS{bmAttributes}=="c0"
    ATTRS{configuration}=="USB Mass Storage"
    ATTRS{quirks}=="0x0"
    ATTRS{ltm_capable}=="no"
    ATTRS{busnum}=="1"
    ATTRS{urbnum}=="1569"
    ATTRS{removable}=="unknown"
    ATTRS{bcdDevice}=="0000"
    ATTRS{speed}=="480"
    ATTRS{idProduct}=="0370"
    ATTRS{bDeviceProtocol}=="00"
    ATTRS{rx_lanes}=="1"
    ATTRS{bDeviceClass}=="00"
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{bMaxPacketSize0}=="64"
    ATTRS{product}=="External HD"
    ATTRS{devnum}=="19"
    ATTRS{idVendor}=="059b"
    ATTRS{version}==" 2.00"
    ATTRS{bMaxPower}=="2mA"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2':
    KERNELS=="1-5.2"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{tx_lanes}=="1"
    ATTRS{bmAttributes}=="e0"
    ATTRS{urbnum}=="200"
    ATTRS{bMaxPacketSize0}=="64"
    ATTRS{quirks}=="0x0"
    ATTRS{manufacturer}=="VIA Labs, Inc.         "
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{rx_lanes}=="1"
    ATTRS{devnum}=="6"
    ATTRS{configuration}==""
    ATTRS{bDeviceClass}=="09"
    ATTRS{busnum}=="1"
    ATTRS{version}==" 2.10"
    ATTRS{speed}=="480"
    ATTRS{idVendor}=="17ef"
    ATTRS{authorized}=="1"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bMaxPower}=="0mA"
    ATTRS{bDeviceProtocol}=="02"
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{maxchild}=="4"
    ATTRS{bcdDevice}=="0a74"
    ATTRS{removable}=="unknown"
    ATTRS{devpath}=="5.2"
    ATTRS{idProduct}=="3071"
    ATTRS{product}=="USB2.0 Hub             "
    ATTRS{ltm_capable}=="no"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1/1-5':
    KERNELS=="1-5"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{product}=="USB2.0 Hub             "
    ATTRS{devnum}=="3"
    ATTRS{rx_lanes}=="1"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{bmAttributes}=="e0"
    ATTRS{devpath}=="5"
    ATTRS{speed}=="480"
    ATTRS{bDeviceClass}=="09"
    ATTRS{idProduct}=="3071"
    ATTRS{removable}=="removable"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bcdDevice}=="0a73"
    ATTRS{quirks}=="0x0"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{busnum}=="1"
    ATTRS{bMaxPower}=="0mA"
    ATTRS{configuration}==""
    ATTRS{tx_lanes}=="1"
    ATTRS{idVendor}=="17ef"
    ATTRS{authorized}=="1"
    ATTRS{manufacturer}=="VIA Labs, Inc.         "
    ATTRS{ltm_capable}=="no"
    ATTRS{urbnum}=="52"
    ATTRS{bDeviceProtocol}=="02"
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{maxchild}=="5"
    ATTRS{version}==" 2.10"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bMaxPacketSize0}=="64"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb1':
    KERNELS=="usb1"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{version}==" 2.00"
    ATTRS{tx_lanes}=="1"
    ATTRS{bMaxPacketSize0}=="64"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{busnum}=="1"
    ATTRS{bcdDevice}=="0500"
    ATTRS{ltm_capable}=="no"
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{serial}=="0000:00:14.0"
    ATTRS{configuration}==""
    ATTRS{devpath}=="0"
    ATTRS{idProduct}=="0002"
    ATTRS{devnum}=="1"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bmAttributes}=="e0"
    ATTRS{bMaxPower}=="0mA"
    ATTRS{product}=="xHCI Host Controller"
    ATTRS{speed}=="480"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{maxchild}=="12"
    ATTRS{authorized}=="1"
    ATTRS{urbnum}=="92"
    ATTRS{idVendor}=="1d6b"
    ATTRS{bDeviceProtocol}=="01"
    ATTRS{quirks}=="0x0"
    ATTRS{bDeviceClass}=="09"
    ATTRS{manufacturer}=="Linux 5.0.0-15-generic xhci-hcd"
    ATTRS{interface_authorized_default}=="1"
    ATTRS{authorized_default}=="1"
    ATTRS{rx_lanes}=="1"
    ATTRS{removable}=="unknown"

  looking at parent device '/devices/pci0000:00/0000:00:14.0':
    KERNELS=="0000:00:14.0"
    SUBSYSTEMS=="pci"
    DRIVERS=="xhci_hcd"
    ATTRS{revision}=="0x30"
    ATTRS{d3cold_allowed}=="1"
    ATTRS{enable}=="1"
    ATTRS{ari_enabled}=="0"
    ATTRS{broken_parity_status}=="0"
    ATTRS{subsystem_device}=="0x2279"
    ATTRS{local_cpulist}=="0-7"
    ATTRS{irq}=="127"
    ATTRS{vendor}=="0x8086"
    ATTRS{msi_bus}=="1"
    ATTRS{device}=="0x9ded"
    ATTRS{dbc}=="disabled"
    ATTRS{local_cpus}=="ff"
    ATTRS{consistent_dma_mask_bits}=="64"
    ATTRS{numa_node}=="-1"
    ATTRS{dma_mask_bits}=="64"
    ATTRS{class}=="0x0c0330"
    ATTRS{subsystem_vendor}=="0x17aa"
    ATTRS{driver_override}=="(null)"

  looking at parent device '/devices/pci0000:00':
    KERNELS=="pci0000:00"
    SUBSYSTEMS==""
    DRIVERS==""

根据此信息，我创建了一个文件/etc.udev/rules.d/10.autobackup.rules：

SUBSYSTEM=="block", ACTION=="add", ATTRS{serial}=="50F26FFFFFFF", RUN+="/usr/bin/touch ~david/test_udev.txt"

重新加载规则sudo udevadm control --reload并运行后udevadm test /block/sda我得到：

This program is for debugging only, it does not run any program
specified by a RUN key. It may show incorrect results, because
some values may be different, or not available at a simulation run.

Load module index
Parsed configuration file /usr/lib/systemd/network/99-default.link
Created link configuration context.
Reading rules file: /etc/udev/rules.d/10.autobackup.rules
Reading rules file: /usr/lib/udev/rules.d/39-usbmuxd.rules
Reading rules file: /usr/lib/udev/rules.d/40-usb_modeswitch.rules
Reading rules file: /usr/lib/udev/rules.d/40-vm-hotadd.rules
Reading rules file: /usr/lib/udev/rules.d/50-apport.rules
Reading rules file: /usr/lib/udev/rules.d/50-firmware.rules
Reading rules file: /usr/lib/udev/rules.d/50-udev-default.rules
Reading rules file: /usr/lib/udev/rules.d/55-dm.rules
Reading rules file: /usr/lib/udev/rules.d/55-ippusbxd.rules
Reading rules file: /usr/lib/udev/rules.d/56-hpmud.rules
Reading rules file: /usr/lib/udev/rules.d/60-block.rules
Reading rules file: /usr/lib/udev/rules.d/60-cdrom_id.rules
Reading rules file: /usr/lib/udev/rules.d/60-crda.rules
Reading rules file: /usr/lib/udev/rules.d/60-drm.rules
Reading rules file: /usr/lib/udev/rules.d/60-evdev.rules
Reading rules file: /usr/lib/udev/rules.d/60-input-id.rules
Reading rules file: /usr/lib/udev/rules.d/60-inputattach.rules
Reading rules file: /usr/lib/udev/rules.d/60-libfprint0.rules
Reading rules file: /usr/lib/udev/rules.d/60-libgphoto2-6.rules
Reading rules file: /usr/lib/udev/rules.d/60-libsane.rules
Reading rules file: /usr/lib/udev/rules.d/60-pcmcia.rules
Reading rules file: /usr/lib/udev/rules.d/60-persistent-alsa.rules
Reading rules file: /usr/lib/udev/rules.d/60-persistent-input.rules
Reading rules file: /usr/lib/udev/rules.d/60-persistent-storage-dm.rules
Reading rules file: /usr/lib/udev/rules.d/60-persistent-storage-tape.rules
Reading rules file: /usr/lib/udev/rules.d/60-persistent-storage.rules
Reading rules file: /usr/lib/udev/rules.d/60-persistent-v4l.rules
Reading rules file: /usr/lib/udev/rules.d/60-sensor.rules
Reading rules file: /usr/lib/udev/rules.d/60-serial.rules
Reading rules file: /usr/lib/udev/rules.d/61-gdm.rules
Reading rules file: /usr/lib/udev/rules.d/61-gnome-settings-daemon-rfkill.rules
Reading rules file: /usr/lib/udev/rules.d/61-persistent-storage-android.rules
Reading rules file: /usr/lib/udev/rules.d/64-btrfs.rules
Reading rules file: /usr/lib/udev/rules.d/64-xorg-xkb.rules
Reading rules file: /usr/lib/udev/rules.d/65-libwacom.rules
Reading rules file: /usr/lib/udev/rules.d/66-snapd-autoimport.rules
Reading rules file: /usr/lib/udev/rules.d/69-cd-sensors.rules
Reading rules file: /usr/lib/udev/rules.d/69-libmtp.rules
Reading rules file: /usr/lib/udev/rules.d/69-wacom.rules
Reading rules file: /usr/lib/udev/rules.d/70-joystick.rules
Reading rules file: /usr/lib/udev/rules.d/70-mouse.rules
Reading rules file: /usr/lib/udev/rules.d/70-power-switch.rules
Reading rules file: /usr/lib/udev/rules.d/70-printers.rules
Reading rules file: /etc/udev/rules.d/70-snap.core.rules
Reading rules file: /usr/lib/udev/rules.d/70-spice-vdagentd.rules
Reading rules file: /usr/lib/udev/rules.d/70-touchpad.rules
Reading rules file: /usr/lib/udev/rules.d/70-u2f.rules
Reading rules file: /usr/lib/udev/rules.d/70-uaccess.rules
Reading rules file: /usr/lib/udev/rules.d/71-power-switch-proliant.rules
Reading rules file: /usr/lib/udev/rules.d/71-seat.rules
Reading rules file: /usr/lib/udev/rules.d/71-u-d-c-gpu-detection.rules
Reading rules file: /usr/lib/udev/rules.d/73-seat-late.rules
Reading rules file: /usr/lib/udev/rules.d/73-special-net-names.rules
Reading rules file: /usr/lib/udev/rules.d/73-usb-net-by-mac.rules
Reading rules file: /usr/lib/udev/rules.d/75-net-description.rules
Reading rules file: /usr/lib/udev/rules.d/75-probe_mtd.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-cinterion-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-dell-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-ericsson-mbm.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-fibocom-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-haier-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-huawei-net-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-longcheer-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-mtk-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-nokia-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-pcmcia-device-blacklist.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-qdl-device-blacklist.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-sierra.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-simtech-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-telit-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-ublox-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-usb-device-blacklist.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-usb-serial-adapters-greylist.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-x22x-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/77-mm-zte-port-types.rules
Reading rules file: /usr/lib/udev/rules.d/78-graphics-card.rules
Reading rules file: /usr/lib/udev/rules.d/78-sound-card.rules
Reading rules file: /usr/lib/udev/rules.d/80-debian-compat.rules
Reading rules file: /usr/lib/udev/rules.d/80-drivers.rules
Reading rules file: /usr/lib/udev/rules.d/80-ifupdown.rules
Reading rules file: /usr/lib/udev/rules.d/80-iio-sensor-proxy.rules
Reading rules file: /usr/lib/udev/rules.d/80-libinput-device-groups.rules
Reading rules file: /usr/lib/udev/rules.d/80-mm-candidate.rules
Reading rules file: /usr/lib/udev/rules.d/80-net-setup-link.rules
Reading rules file: /usr/lib/udev/rules.d/80-udisks2.rules
Reading rules file: /usr/lib/udev/rules.d/84-nm-drivers.rules
Reading rules file: /usr/lib/udev/rules.d/85-brltty.rules
Reading rules file: /usr/lib/udev/rules.d/85-hdparm.rules
Reading rules file: /usr/lib/udev/rules.d/85-hplj10xx.rules
Reading rules file: /usr/lib/udev/rules.d/85-nm-unmanaged.rules
Reading rules file: /usr/lib/udev/rules.d/85-regulatory.rules
Reading rules file: /usr/lib/udev/rules.d/89-alsa-ucm.rules
Reading rules file: /usr/lib/udev/rules.d/90-alsa-restore.rules
Reading rules file: /usr/lib/udev/rules.d/90-bolt.rules
Reading rules file: /usr/lib/udev/rules.d/90-console-setup.rules
Reading rules file: /usr/lib/udev/rules.d/90-fwupd-devices.rules
Reading rules file: /usr/lib/udev/rules.d/90-libinput-model-quirks.rules
Reading rules file: /usr/lib/udev/rules.d/90-nm-thunderbolt.rules
Reading rules file: /usr/lib/udev/rules.d/90-pulseaudio.rules
Reading rules file: /usr/lib/udev/rules.d/95-cd-devices.rules
Reading rules file: /usr/lib/udev/rules.d/95-dm-notify.rules
Reading rules file: /usr/lib/udev/rules.d/95-upower-csr.rules
Reading rules file: /usr/lib/udev/rules.d/95-upower-hid.rules
Reading rules file: /usr/lib/udev/rules.d/95-upower-wup.rules
Reading rules file: /usr/lib/udev/rules.d/97-hid2hci.rules
Reading rules file: /usr/lib/udev/rules.d/99-systemd.rules
Rules contain 393216 bytes tokens (32768 * 12 bytes), 38404 bytes strings
31877 strings (265263 bytes), 28376 de-duplicated (230361 bytes), 3502 trie nodes used
Invalid inotify descriptor.
Starting 'ata_id --export /dev/sda'
Process 'ata_id --export /dev/sda' failed with exit code 1.
sda: Failed to create symlink '/dev/disk/by-id/usb-ST310005_20AS_50F26FFFFFFF-0:0.tmp-b8:0' to '../../sda': Permission denied
DEVPATH=/devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.2/1-5.2.3/1-5.2.3:1.0/host0/target0:0:0/0:0:0:0/block/sda
DEVNAME=/dev/sda
DEVTYPE=disk
MAJOR=8
MINOR=0
ACTION=add
SUBSYSTEM=block
ID_VENDOR=ST310005
ID_VENDOR_ENC=ST310005
ID_VENDOR_ID=059b
ID_MODEL=20AS
ID_MODEL_ENC=20AS\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20
ID_MODEL_ID=0370
ID_REVISION=0000
ID_SERIAL=ST310005_20AS_50F26FFFFFFF-0:0
ID_SERIAL_SHORT=50F26FFFFFFF
ID_TYPE=disk
ID_INSTANCE=0:0
ID_BUS=usb
ID_USB_INTERFACES=:080650:
ID_USB_INTERFACE_NUM=00
ID_USB_DRIVER=usb-storage
DEVLINKS=/dev/disk/by-path/pci-0000:00:14.0-usb-0:5.2.3:1.0-scsi-0:0:0:0 /dev/disk/by-id/usb-ST310005_20AS_50F26FFFFFFF-0:0
ID_PATH=pci-0000:00:14.0-usb-0:5.2.3:1.0-scsi-0:0:0:0
ID_PATH_TAG=pci-0000_00_14_0-usb-0_5_2_3_1_0-scsi-0_0_0_0
TAGS=:systemd:
USEC_INITIALIZED=3351039864
run: '/usr/bin/unshare -m /usr/bin/snap auto-import --mount=/dev/sda'
run: '/usr/bin/touch ~david/test_udev.txt'
run: '/lib/udev/hdparm'
Unload module index
Unloaded link configuration context.

这似乎表明touch我的脚本中的命令应该在添加 USB 驱动器时执行（并且在安装驱动器后，这是我执行备份时需要的限制）。但是，下次我添加驱动器时（将其关闭然后打开），没有创建任何文件~david/test_udev.txt。

执行sudo udevadm trigger也无法创建文件。

最终目标是执行备份命令，但此时我只是试图接触一个文件以让基本功能正常运作......

答案1

编辑：事实证明，我的具体情况/问题与我的加密主目录有关，并且仅使用 systemd 就可以使其正常工作，尽管每次登录时都必须启动该单元。有关更多信息，请参阅这里。

进一步研究后发现，触发备份脚本（根据“长时间”的定义，这可能是“长时间运行”）并不是最好的方法（它可能会延迟其他 udev 内容）。相反，最好让 udev“想要”一个 systemd 用户单元，然后触发实际的备份脚本。以下是我所做的：

在 GParted 中标记驱动器（例如，称为“备份”），以便它们始终安装在相同的安装点。

在 ~/.config/systemd/user/auto-usb-backup.service 中添加用户 systemd 单元：

[Unit]
Description=Autobackup to USB drive

[Service]
ExecStart=/home/david/Documents/computer/backup/scripts/backup_to_usb.sh

重新加载守护进程：systemctl --user daemon-reload以便它知道新的单元。

然后，添加一条 udev 规则，当安装带有“备份”分区的 USB 驱动器时触发该单元。在 /etc/udev/rules.d/90-auto-usb-backup.rules 中创建一个包含以下内容的 udev 规则

SUBSYSTEM=="block", ACTION=="add", ENV{ID_FS_LABEL}=="backup", TAG+="systemd", ENV{SYSTEMD_USER_WANTS}="auto-usb-backup.service"

ID_FS_LABEL 参数名称和值是使用udevadm monitor --environment --udev和插入驱动器获得的，但lsusb（和其-v选项）也udevadm info -a -p $(udevadm info -q path -n /dev/sda)可能对微调规则有用（例如，仅根据特定驱动器的序列号触发 udev 规则）。

重新加载 udev 以应用新规则：sudo udevadm control --reload

检查规则是否会为驱动器触发udevadm test /block/sda（sda当前驱动器挂载点在哪里）：您应该TAGS=:systemd:在输出中看到。

最后，删除并添加驱动器：上面定义的 systemd 用户单元中的脚本应该会执行。您可以使用journalctl --user-unit auto-usb-backup -r -b（请注意，在某些系统上，--user-unit选项可能是-u相反的）仔细检查（并调试）。

注意：看来脚本在驱动器完成安装之前就被触发，因此 systemd 单元调用的备份脚本有一个等待循环来休眠，直到它寻找的文件夹可用。

有帮助的资源：

https://vic.demuzere.be/articles/using-systemd-user-units/

https://borgbackup.readthedocs.io/en/stable/deployment/automated-local.html

答案1

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