sng: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/sng - from package: sng

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