dwi_mask_bad_slices: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/cmtk/bin/dwi_mask_bad_slices - from package: cmtk

You may install the required package with command apt-get install {package}

Error in other languages:
dwi_mask_bad_slices: bevel nie gevind nie
dwi_mask_bad_slices: comandă negăsită
dwi_mask_bad_slices: comando não encontrado
dwi_mask_bad_slices: commande introuvable
dwi_mask_bad_slices: command not found
dwi_mask_bad_slices: käsku ei ole
dwi_mask_bad_slices: không tìm thấy lệnh
dwi_mask_bad_slices: komanda nerasta
dwi_mask_bad_slices: Kommando nicht gefunden.
dwi_mask_bad_slices: kommandot finns inte
dwi_mask_bad_slices: komut yok
dwi_mask_bad_slices: nie znaleziono polecenia
dwi_mask_bad_slices: níor aimsíodh an t-ordú
dwi_mask_bad_slices: no se encontró la orden
dwi_mask_bad_slices: no s'ha trobat l'ordre
dwi_mask_bad_slices: opdracht niet gevonden
dwi_mask_bad_slices: parancs nem található
dwi_mask_bad_slices: perintah tidak ditemukan
dwi_mask_bad_slices: príkaz nenájdený
dwi_mask_bad_slices: příkaz nenalezen
dwi_mask_bad_slices: команда не найдена
dwi_mask_bad_slices: командата не е открита
dwi_mask_bad_slices: 命令找不到
dwi_mask_bad_slices: コマンドが見つかりません