[SOLVED] shell script problem

[Aydan]

I'm trying to run the raspberry form an LVM root, and got it sort of working, but the LVM doesn't come up at boot by itself. I have to start is in the console manually.
I've narrowed it down to the lvm2 script that is supposed to activate the lvm. But it doesn't.
Here's the script:

Code: Select all

#!/bin/sh

PREREQ="mdadm mdrun multipath"

prereqs()
{
        echo "$PREREQ"
}

case $1 in
# get pre-requisites
prereqs)
        prereqs
        exit 0
        ;;
esac

activate_vg()
{
        local dev="$1"

        # Make sure that we have a non-empty argument
        if [ -z "$dev" ]; then
                echo dev is empty
                return 1
        fi
        echo $dev

        # Take care of lilo boot arg, risky activating of all vg
        case "$dev" in
        fe[0-9]*)
                lvm vgchange -aly --ignorelockingfailure
                echo whatever1
                exit 0
                ;;
        # FIXME: check major
        /dev/root)
                lvm vgchange -aly --ignorelockingfailure
                echo whatever2
                exit 0
                ;;
        esac

        # Make sure that we have a d-m path
        dev="${dev#/dev/mapper/}"
        echo "dev is $dev and arg 1 is $1"
        if [ "$dev" = "$1" ]; then
                echo "returning 1"
                return 1
        fi

        eval $(dmsetup splitname --nameprefixes --noheadings --rows "$dev")
        echo "$DM_VG_NAME"
        echo "$DM_LV_NAME"

        if [ "$DM_VG_NAME" ] && [ "$DM_LV_NAME" ]; then
                lvm lvchange -aly --ignorelockingfailure "$DM_VG_NAME/$DM_LV_NAME"
                rc=$?
                if [ $rc = 5 ]; then
                        echo "Unable to find LVM volume $DM_VG_NAME/$DM_LV_NAME"
                fi
        fi
}

if [ ! -e /sbin/lvm ]; then
        echo "no /sbin/lvm"
        exit 0
fi

echo modprobing dm-mod
modprobe -q dm-mod

activate_vg "$ROOT"
activate_vg "$resume"

exit 0

The reason is that the line

Code: Select all

dev="${dev#/dev/mapper/}"

and the subsequent

Code: Select all

 if [ "$dev" = "$1" ]

is always true.

So the syntax of

Code: Select all

dev="${dev#/dev/mapper/}"

eludes me.

I think it's supposed to concatenate /dev/mapper to $dev, but the result is only $dev but $dev is the same as $1 so the subsequent activateion of the volume never gets called.
Is it that busybox behaves differently than other shells or what is going on here?

Regards
Aydan

[Aydan]

OK, I figured out a solution.
I was trying to mount /dev/lvmroot/root as root but that would screw up the lvm script because it wants a path starting with /dev/mapper.
mounting /dev/mapper/lvmroot-root works.
And I figured out what dev="${dev#/dev/mapper/}" does. It gives the remainder of $dev without /dev/mapper/

Regards
Aydan