yaps: 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/yaps - from package: abcmidi

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

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