mount.lockfs: command not found

Have You tried accessing the binary with the full path?

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:

/sbin/mount.lockfs - from package: bilibop-lockfs

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