yhsm-keystore-unlock: 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-keystore-unlock - from package: yhsm-tools

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

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