Нужна помощь с отладкой Bash-скрипта

Написал скрипт:

#!/bin/bash
# set -v
E_WRONGCOMMAND=1
E_WRONGPARTITION=2
E_ERASE=3

fs_write() {
echo fs_write $*
local param_fs=$1
local param_file=$2
local param_device=$3
exportfs none
exportfs $param_fs
device_detect $param_device
echo sudo dd if=$param_file of=$device bs=2048||return $?
sync
exportfs none
}

fs_read() {
echo fs_read $*
local param_fs=$1
local param_file=$2
local param_device=$3
exportfs none
exportfs $param_fs
device_detect $param_device
echo sudo dd if=$device of=$param_file bs=2048||return $?
exportfs none
}

fs_erase() {
echo fs_erase $*
local param_fs=$1
local param_device=$2
case $param_fs in
 hboot) echo Erasing partition $param_fs not allowed: it will brick Your phone!; exit $E_ERASE;;
 emmc)  echo Erasing partition $param_fs not allowed: it will brick Your phone!; exit $E_ERASE;;
 none)  echo Unable to erase partition $param_fs!; exit $E_ERASE;;
 *) fs_write $param_fs /dev/zero $param_device ;; 
esac
}

exportfs() {
echo exportfs $*
case $1 in
 hboot)    partition=/dev/block/mmcblk0p12;;
 radio)    partition=/dev/block/mmcblk0p17;;
 adsp)     partition=/dev/block/mmcblk0p19;;
 boot)     partition=/dev/block/mmcblk0p20;;
 recovery) partition=/dev/block/mmcblk0p21;;
 system)   partition=/dev/block/mmcblk0p22;;
 data)     partition=/dev/block/mmcblk0p23;;
 cache)    partition=/dev/block/mmcblk0p24;;
 devlog)   partition=/dev/block/mmcblk0p27;;
 emmc)     partition=/dev/block/mmcblk0;;
 sdcard)   partition=/dev/block/mmcblk1;;
 none)     partition=/dev/null;;
 *) echo Wrong partition: $1; exit $E_WRONGPARTITION;;
esac
legacy="/sys/devices/platform/usb_mass_storage/lun0/file"
recent="/sys/devices/platform/msm_otg/msm_hsusb/gadget/lun0/file"
echo 'until /opt/android-sdk-update-manager/platform-tools/adb shell "echo $partition > $legacy" ; do sleep 1;done'
echo 'until /opt/android-sdk-update-manager/platform-tools/adb shell "echo $partition > $recent" ; do sleep 1;done'
}

device_detect() {
echo "device_detect $*"
if [[ "z$1" != "z" ]] ;then device=$1; return; fi
device=`find /dev/disk/by-id/|grep -i Android|sort|head -n 1` ## TODO: write better detect function!
}

usage() {
echo "Usage: adbflasher flash    hdsp     boot.img   [device_to_flash]
       adbflasher flash    recovery recovery.img [device_to_flash]
       adbflasher flash    radio    radio.img    [device_to_flash]
       adbflasher flash    hboot    hboot.img    [device_to_flash] ## Dangerous!
       adbflasher flash    adsp     adsp.img     [device_to_flash]
       adbflasher flash    emmc     emmc.img     [device_to_flash] ## Extremly dangerous! DO NOT FLASH ANY FILE EXCEPT YOUR HAVE READ FROM YOUR PHONE EARLIER!
       adbflasher exportfs {hboot|radio|adsp|boot|recovery|system|data|cache|devlog|emmc|sdcard|none} 
       ## Might br dangerous! ALWAYS do exportfs none before exportfs another partition!
       adbflasher read     {hboot|radio|adsp|boot|recovery|system|data|cache|devlog|emmc|sdcard|none} filename.img [device_to_read]
       adbflasher erase    {radio|adsp|boot|recovery|system|data|cache|devlog|sdcard} [device_to_erase]"
}

if [[ $# -eq 0 ]] ;then usage; exit $E_WRONGCOMMAND; fi

case $1 in
exportfs) exportfs $2 ;;
erase)    fs_erase $2 $3    |exit $? ;;
read)     fs_read  $2 $3 $4 |exit $? ;;
flash)    fs_write $2 $3 $4 |exit $? ;;
*)        echo "Wrong command: $1"; usage; exit $E_WRONGCOMMAND ;;
esac

#until /opt/android-sdk-update-manager/platform-tools/adb reboot ; do sleep 1;done

Проблема в том, что echo в нём работает только в случае выполнения с неверной командой, то есть к примеру ./adbflasher error выведет справку, а adbflasher exportfs emmc завершится без единого сообщения, с кодом 0. Хотя по идее обязано вывести хотя бы строку с "exportfs emmc", что в самом начале функции exportfs.
Ума не приложу, где ошибка! Перенаправления ввода-вывода не использовались вообще ведь, куда оно может выводить сообщения?
Буду очень признателен за любые пояснения. Спасибо.