sha512sum: 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/bin/sha512sum - from package: coreutils

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

On Debian possible default full paths are:

/usr/bin/sha512sum - from package: coreutils

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

Error in other languages:
sha512sum: bevel nie gevind nie
sha512sum: comandă negăsită
sha512sum: comando não encontrado
sha512sum: commande introuvable
sha512sum: command not found
sha512sum: käsku ei ole
sha512sum: không tìm thấy lệnh
sha512sum: komanda nerasta
sha512sum: Kommando nicht gefunden.
sha512sum: kommandot finns inte
sha512sum: komut yok
sha512sum: nie znaleziono polecenia
sha512sum: níor aimsíodh an t-ordú
sha512sum: no se encontró la orden
sha512sum: no s'ha trobat l'ordre
sha512sum: opdracht niet gevonden
sha512sum: parancs nem található
sha512sum: perintah tidak ditemukan
sha512sum: príkaz nenájdený
sha512sum: příkaz nenalezen
sha512sum: команда не найдена
sha512sum: командата не е открита
sha512sum: 命令找不到
sha512sum: コマンドが見つかりません