shnfix: 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/shnfix - from package: shntool

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

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