openmsx: 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/openmsx - from package: openmsx

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

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