shnlen: 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/shnlen - from package: shntool

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

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