yhsm-validation-server: 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/sbin/yhsm-validation-server - from package: yhsm-validation-server

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

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