lava-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/bin/lava-server - from package: lava-server

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

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