chpasswd: 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/chpasswd - from package: shadow-utils

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

On Debian possible default full paths are:

/usr/sbin/chpasswd - from package: passwd

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

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