#!/bin/bash
#
# Script to reinitialise real disks on BCPC DNY cluster where disks b
# ... h are given over to Ceph
#
# location of sgdisk
setglobal TOOLPATH = '/sbin'
# name of sgdisk binary
setglobal DISKCOMMAND = 'sgdisk'
# what to invoke sgdisk with
setglobal ZAPFLAGS = '"-Zog'"
setglobal GUARDFILE = '/etc/ceph-disks-zapped'

if dpkg -s gdisk !2 >/dev/null | grep -q Status.*installed {
    echo "gdisk is installed"
} else {
    echo "install gdisk..."
    apt-get install --allow-unauthenticated -y gdisk
}
if [[ -z `which $DISKCOMMAND` ]] {
    echo "can't find '$DISKCOMMAND'"
    exit
}

# Run zap command for all disks present which are not mounted
if [[ ! -f $GUARDFILE ]] {
    # get all /dev/sd[a-z] devices mounted
    setglobal mounted_whole_disks = $[df -kh | cut -f 1 -d' ' | tail -n+2 | grep '^/dev/sd' | sed 's/[0-9]/|/' | sort -u]
    # make a regular expression of disks (e.g. /dev/sda|/dev/sdd|...|)
    setglobal mounted_disk_regex = $[for disk in [$mounted_whole_disks] { echo -n $disk; }]

    for disk in [$[ls /dev/sd[a-z]]] {
        if ! echo $disk | egrep -q $(mounted_disk_regex:0:-1) {
            echo "#### Overwriting $disk with $DISKCOMMAND $ZAPFLAGS"
            $TOOLPATH/$DISKCOMMAND $ZAPFLAGS $disk
        } else {
            echo "#### Skipping mounted disk $disk"
        }
    }
} else {
    echo "disks look zapped already"
}
touch /etc/ceph-disks-zapped