How to start a systemd service after mount command
With ConditionPathExists= a file existence condition is checked before a unit is started. If the specified absolute path name does not exist, the condition will fail. If the absolute path name passed to ConditionPathExists= is prefixed with an exclamation mark ("!"), the test is negated, and the unit is only started if the path does not exist.
ConditionPathIsMountPoint= is similar to ConditionPathExists= but verifies whether a certain path exists and is a mount point.
Seems like the easiest method is to include
ConditionPathIsMountPoint=/mnt/backup
In your [Unit]
section. Though this doesn't check which device is mounted there, though in the case of creating a backup the user may not be picky.
You'd probably also need Restart=on-failure
to continue trying to start the service.
A more precise method would be to write a udev
rule that starts the service when a particular device is mounted.
Start by finding your device in lsusb. Note the ID (eg 0a81:0101)
Create a new udev rules file in /etc/udev/rules.d/ via sudoedit /etc/udev/rules.d/100-mount-videos.rulesand plonk a new rule in there like this:
ACTION=="add", ATTRS{idVendor}=="0a81", ATTRS{idProduct}=="0101", RUN+="/home/your_username/bin/mount_videos.sh"
You could just replace the RUN+=
with RUN+=/usr/bin/systemctl start backup.service
or whatever you called your service
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Loligans
Updated on September 18, 2022Comments
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Loligans over 1 year
I am working on a lab for my linux class and the teacher is teaching us about Systemd.
How do I create a service that starts a script when a specific device is mounted using this command:
mount /dev/xvdc1 /mnt/backup
What I have tried
- Using a Timer I checked if
/mnt/backup
was a mount point. (teacher would not accept it. It must be strictly event driven) - Creating a .mount unit and making the .service unit require the .mount unit. This approach did not start the script when executing the command:
mount /dev/xvdc1 /mnt/backup
I think I may be approaching this problem the wrong way. This is the lab problem.
"Create a unit file that copies all the files from
/mnt/backup
using rsync as soon as/dev/xvdc1
is mounted."What I know:
- The device that will be mounted will always be
/dev/xvdc1
- The mount point of the device will always be
/mnt/backup
- The Service must be started based on
/dev/xvdc1
being mounted
Here is my .service unit file
[Unit] Description=Starts a backup for /dev/xvdc1 when mounted using the mount command. [Service] Type=simple ExecStart=/root/backupscript.sh ExecStop=/bin/kill -HUP $MAINPID [Install] WantedBy=multi-user.target
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Loligans over 7 yearsI found this question <unix.stackexchange.com/questions/91443/…> but it seems like I will have to create a .mount unit instead
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Julie Pelletier over 7 yearsTry it and if it works, you can answer your own question. ;)
- Using a Timer I checked if