ckpasswd: 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/news/bin/auth/passwd/ckpasswd - from package: inn2

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

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