shnconv: 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/shnconv - from package: shntool

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

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