pwck: 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/pwck - from package: shadow-utils

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

On Debian possible default full paths are:

/usr/sbin/pwck - from package: passwd

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

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