hwclock: 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:

/sbin/hwclock - from package: util-linux-ng
/usr/sbin/hwclock - from package: util-linux-ng

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

On Debian possible default full paths are:

/sbin/hwclock - from package: util-linux

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

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