faust2mathdoc: 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/faust2mathdoc - from package: faust

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

Error in other languages:
faust2mathdoc: bevel nie gevind nie
faust2mathdoc: comandă negăsită
faust2mathdoc: comando não encontrado
faust2mathdoc: commande introuvable
faust2mathdoc: command not found
faust2mathdoc: käsku ei ole
faust2mathdoc: không tìm thấy lệnh
faust2mathdoc: komanda nerasta
faust2mathdoc: Kommando nicht gefunden.
faust2mathdoc: kommandot finns inte
faust2mathdoc: komut yok
faust2mathdoc: nie znaleziono polecenia
faust2mathdoc: níor aimsíodh an t-ordú
faust2mathdoc: no se encontró la orden
faust2mathdoc: no s'ha trobat l'ordre
faust2mathdoc: opdracht niet gevonden
faust2mathdoc: parancs nem található
faust2mathdoc: perintah tidak ditemukan
faust2mathdoc: príkaz nenájdený
faust2mathdoc: příkaz nenalezen
faust2mathdoc: команда не найдена
faust2mathdoc: командата не е открита
faust2mathdoc: 命令找不到
faust2mathdoc: コマンドが見つかりません