passing arguments to shell script from udev rules file

shell variables export environment-variables udev
Talespin_Kit picture Talespin_Kit · Dec 4, 2012 · Viewed 13.4k times · Source

In the rules file a script is executed by passing the arguments "LABEL" and "DEVNAME" for mounting

ACTION=="add", RUN+="/appmount/scripts/usb_mount.sh %E{ID_FS_LABEL} %E{DEVNAME}"

In the usb_mount.sh file printing the arguments value as 

echo "LABEL: $1 DEVNAME: $2" # this does not work reliably

Some of the devices have empty LABEL field and hence the DEVNAME is printed as the label. In the bash script we can pass the args in double quotes and it will work even if the args are null.

What is the equivalent of the same for passing args to udev rules?

The workaround to this problem might be to switch the order of the arguments. Is there any reliable way?

Answer

Carsten Scholtes picture Carsten Scholtes · Feb 20, 2013

You should be able to use single quotes instead of the double quotes you mentioned:

ACTION=="add", RUN+="/appmount/scripts/usb_mount.sh '%E{ID_FS_LABEL}' '%E{DEVNAME}'"

Beware: I didn't test this. Maybe variable substitution will fail within single quotes...

Quoting from man udev about the key "RUN":

The program name and following arguments are separated by spaces. Single quotes can be used to specify arguments with spaces.

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