csound-play-harmonic-interval.sh: 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/share/solfege/exercises/standard/lesson-files/bin/csound-play-harmonic-interval.sh - from package: solfege

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

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