cracklib-unpacker: 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 CentOS possible default full paths are:

/usr/sbin/cracklib-unpacker - from package: cracklib

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/sbin/cracklib-unpacker - from package: cracklib-runtime

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

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