#!/bin/bash

function del_partitions(){
        echo "d"
        echo "1"
        echo "d"
        echo "2"
        echo "d"
        echo "3"
        echo "d"
        [ "$SPECIAL4" = "4" ] || echo "4"
}

function enable_errcheck(){
        echo "v"
}

function add_partition(){
        echo "n"
        echo "$1"
        [ "$1" != "l" -a "$2" != "$SPECIAL4" ] && echo "$2"
        echo
        echo "$3"
        if [ "$4" != "" ]; then
                echo "t"
                echo "$2"
                echo "$4"
        fi
}

function make_partitions(){
        del_partitions
        enable_errcheck
        [ "$UNITS" = "K" ] && echo "u"
        add_partition e 1 "+$SZ_HDA1$UNITS"
        add_partition l 5 "+$SZ_HDA5$UNITS" 83
        add_partition l 6 ""                82
        add_partition p 2 "+$SZ_HDA2$UNITS" 83
        add_partition p 3 "+$SZ_HDA3$UNITS" 10
        add_partition p 4 ""                83
        echo "a"
        echo "5"
        echo "p"
        echo $COMMIT
}

function errcheck(){
        DOECHO=0
        ERRCHECK=0
        while read x ; do
                [[ "$x" == Disk\ ${DEV}:*             ]] && DOECHO=1
                [[ "$x" == Command\ \(m\ for\ help\): ]] && DOECHO=0
                [ $DOECHO -eq 1 ] && [[ "$x" != *does\ not\ end\ on* ]] && echo "$x" >&2
                [[ "$x" == *\ unallocated\ sectors    ]] && ERRCHECK=1
                if [ $ERRCHECK -eq 1 ]; then
                        if [[ "$x" == *out\ of\ range.          \
                           || "$x" == *got\ EOF\ thrice*        \
                           || "$x" == *No\ free\ sectors*       \
                           || "$x" == *unknown\ command*        \
                           ]]
                        then
                                echo "ERROR: fdisk: $x" 1>&2
                                exit 1
                        fi
                fi
        done
        exit 0
}

## First parameter is the device path, eg. /dev/hda:
[ "$1" = "" ] && echo "missing device path" && exit 1
DEV=$1

## The default is to "just pretend", and not actually do anything for real.
## Supply "COMMIT" on the command line to actually write the new partition info.
COMMIT=q
[ "$2" = "COMMIT" ] && COMMIT=w

## Figure out how big $DEV is, in kilobytes:
DEV_KB=`sed -n -e"s/  *[0-9][0-9]*  *[0-9][0-9]* *\([0-9]*\) ${DEV##*/}\$/\1/p" < /proc/partitions`
if [ "$DEV_KB" = "" ]; then
        echo "$DEV: not found"
        exit 1
fi

## Newer fdisk versions don't always prompt for partition number 4, but the empeg does:
SPECIAL4="4"
[ "`fdisk -v`" = "fdisk v2.10d" ] && SPECIAL4=NONE      ## empeg

## minimum partition sizes, in $UNITS (defined below):
SZ_HDA5=16      ## root
SZ_HDA6=64      ## swap
SZ_HDA1=$(( SZ_HDA5 + SZ_HDA6 ))
SZ_HDA2=32      ## spare
SZ_HDA3=32      ## dynamic data
SZ_HDA4=        ## FIDs, use all remaining space

## allocation units, normally "M" (megabytes), or possibly "K" (kilobytes):
UNITS=M

## "K" kilobytes: only for testing here on a tiny drive I have:
SZ_TOTAL=$(( SZ_HDA1 + SZ_HDA2 + SZ_HDA3 + 128 ))
[ $(( SZ_TOTAL * 1024 )) -ge $DEV_KB ] && UNITS=K

echo
[ "$SPECIAL4" = "4" ] || echo "$DEV: ${DEV_KB} KB"
make_partitions $COMMIT | fdisk $DEV 2>&1 | errcheck || exit 1
echo "Success"

Disk /dev/hda: 16 heads, 63 sectors, 38760 cylinders
Units = cylinders of 1008 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hda1             1        66     33232+   5  Extended
/dev/hda2            67       132     33264   83  Linux
/dev/hda3           133       165     16632   10  OPUS
/dev/hda4           166     38760  19451880   83  Linux
/dev/hda5             1        33     16569   83  Linux
/dev/hda6            34        66     16600+  82  Linux swap

Disk /dev/hda: 16 heads, 63 sectors, 38760 cylinders
Units = cylinders of 1008 * 512 bytes

Device Boot    Start       End    Blocks   Id  System
/dev/hda1             1       163     82120+   5  Extended
/dev/hda2           164       229     33264   83  Linux
/dev/hda3           230       295     33264   10  OPUS
/dev/hda4           296     38760  19386360   83  Linux
/dev/hda5   *         1        33     16569   83  Linux
/dev/hda6            34       163     65488+  82  Linux swap