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Help with udev trigger

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  Help with udev trigger Bhasker C V <bhasker@unixindia.com> - 2018-05-18 10:50 +0200
    Re: Help with udev trigger Reco <recoverym4n@gmail.com> - 2018-05-18 13:40 +0200
      Re: Help with udev trigger Bhasker C V <bhasker@unixindia.com> - 2018-05-21 10:40 +0200
    Re: Help with udev trigger songbird <songbird@anthive.com> - 2018-05-18 14:00 +0200

#195870 — Help with udev trigger

Hi,

 Version: buster
 I do a manual cryptsetup to create my home directory after system boots up
 I want to run fsck every time the device node is created from luks

 I added this udev rule

ACTION="change",DEVTYPE="disk",ID_FS_UUID="cf1b64cf-7a62-4a43-ad44-6c68f2bbdec5"
RUN+="/bin/btrfsck /dev/mapper/home"

But this rule is not getting triggered. Could someone help please to
point out what mistake I am doing ?

The following is what I get when the device is added from which I
deduced the above trigger line

UDEV  [3110.764972] change   /devices/virtual/block/dm-12 (block)
.ID_FS_TYPE_NEW=btrfs
ACTION=change
DEVLINKS=/dev/disk/by-id/dm-uuid-CRYPT-LUKS1-f064023b1b2d41639634f5bdf2430794-home
/dev/disk/by-id/dm-name-home
/dev/disk/by-uuid/cf1b64cf-7a62-4a43-ad44-6c68f2bbdec5
/dev/mapper/home
DEVNAME=/dev/dm-12
DEVPATH=/devices/virtual/block/dm-12
DEVTYPE=disk
DM_ACTIVATION=1
DM_COOKIE=6306419
DM_NAME=home
DM_STATE=ACTIVE
DM_SUSPENDED=0
DM_TABLE_STATE=LIVE
DM_UDEV_DISABLE_LIBRARY_FALLBACK_FLAG=1
DM_UDEV_PRIMARY_SOURCE_FLAG=1
DM_UDEV_RULES=1
DM_UDEV_RULES_VSN=2
DM_UUID=CRYPT-LUKS1-f064023b1b2d41639634f5bdf2430794-home
ID_BTRFS_READY=1
ID_FS_TYPE=btrfs
ID_FS_USAGE=filesystem
ID_FS_UUID=cf1b64cf-7a62-4a43-ad44-6c68f2bbdec5
ID_FS_UUID_ENC=cf1b64cf-7a62-4a43-ad44-6c68f2bbdec5
ID_FS_UUID_SUB=6e20311a-a369-4929-9e40-44b63e3eb563
ID_FS_UUID_SUB_ENC=6e20311a-a369-4929-9e40-44b63e3eb563
MAJOR=253
MINOR=12
SEQNUM=2242
SUBSYSTEM=block
TAGS=:systemd:
USEC_INITIALIZED=3110669103

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#195873

	Hi.

On Fri, May 18, 2018 at 09:26:47AM +0100, Bhasker C V wrote:
> Hi,
> 
>  Version: buster
>  I do a manual cryptsetup to create my home directory after system boots up
>  I want to run fsck every time the device node is created from luks
> 
>  I added this udev rule
> 
> ACTION="change",DEVTYPE="disk",ID_FS_UUID="cf1b64cf-7a62-4a43-ad44-6c68f2bbdec5"
> RUN+="/bin/btrfsck /dev/mapper/home"
> 
> But this rule is not getting triggered. Could someone help please to
> point out what mistake I am doing ?

You have five mistakes here, actually:

1) udev rules use C-like syntax for comparison (==) and assingment (=).
Your rule tests nothing, it just assigns some values.

2) All udev 'attributes' have type, and you must specify it.
For instance DEVTYPE and ID_FS_UUID are ENVIRONMENT.

3) 'change' applies to changing device state. It's 'add' for device
creation.

4) RUN should go after a coma.

5) You're not supposed to spawn long-running processes from udev rules
directly. Utilize systemd.


Taking all this into the account, your rule should look like this (one
like, coma separated values):

ACTION=="add", ENV{DEVTYPE}=="disk",ENV{ID_FS_UUID}=="cf1b64cf-7a62-4a43-ad44-6c68f2bbdec5",RUN+="/bin/systemctl start my_brtfs_home_checking.service"

Your custom service file - like this:

[Service]
Type=oneshot
ExecStart=/bin/btrfsck /dev/mapper/home

Reco

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#195954

Thanks. I will try this

On Fri, May 18, 2018 at 12:21 PM, Reco <recoverym4n@gmail.com> wrote:
>         Hi.
>
> On Fri, May 18, 2018 at 09:26:47AM +0100, Bhasker C V wrote:
>> Hi,
>>
>>  Version: buster
>>  I do a manual cryptsetup to create my home directory after system boots up
>>  I want to run fsck every time the device node is created from luks
>>
>>  I added this udev rule
>>
>> ACTION="change",DEVTYPE="disk",ID_FS_UUID="cf1b64cf-7a62-4a43-ad44-6c68f2bbdec5"
>> RUN+="/bin/btrfsck /dev/mapper/home"
>>
>> But this rule is not getting triggered. Could someone help please to
>> point out what mistake I am doing ?
>
> You have five mistakes here, actually:
>
> 1) udev rules use C-like syntax for comparison (==) and assingment (=).
> Your rule tests nothing, it just assigns some values.
>
> 2) All udev 'attributes' have type, and you must specify it.
> For instance DEVTYPE and ID_FS_UUID are ENVIRONMENT.
>
> 3) 'change' applies to changing device state. It's 'add' for device
> creation.
>
> 4) RUN should go after a coma.
>
> 5) You're not supposed to spawn long-running processes from udev rules
> directly. Utilize systemd.
>
>
> Taking all this into the account, your rule should look like this (one
> like, coma separated values):
>
> ACTION=="add", ENV{DEVTYPE}=="disk",ENV{ID_FS_UUID}=="cf1b64cf-7a62-4a43-ad44-6c68f2bbdec5",RUN+="/bin/systemctl start my_brtfs_home_checking.service"
>
> Your custom service file - like this:
>
> [Service]
> Type=oneshot
> ExecStart=/bin/btrfsck /dev/mapper/home
>
> Reco
>

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#195874

Bhasker C V wrote:
> Hi,
>
>  Version: buster
>  I do a manual cryptsetup to create my home directory after system boots up
>  I want to run fsck every time the device node is created from luks
>
>  I added this udev rule
>
> ACTION="change",DEVTYPE="disk",ID_FS_UUID="cf1b64cf-7a62-4a43-ad44-6c68f2bbdec5"
> RUN+="/bin/btrfsck /dev/mapper/home"
>
> But this rule is not getting triggered. Could someone help please to
> point out what mistake I am doing ?

  i'm guessing that after the boot that there is no
change happening to trigger it...

  what happens if you make the rule "add|change" instead?


  songbird

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