s9hts: 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/s9hts - from package: scheme9

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

Error in other languages:
s9hts: bevel nie gevind nie
s9hts: comandă negăsită
s9hts: comando não encontrado
s9hts: commande introuvable
s9hts: command not found
s9hts: käsku ei ole
s9hts: không tìm thấy lệnh
s9hts: komanda nerasta
s9hts: Kommando nicht gefunden.
s9hts: kommandot finns inte
s9hts: komut yok
s9hts: nie znaleziono polecenia
s9hts: níor aimsíodh an t-ordú
s9hts: no se encontró la orden
s9hts: no s'ha trobat l'ordre
s9hts: opdracht niet gevonden
s9hts: parancs nem található
s9hts: perintah tidak ditemukan
s9hts: príkaz nenájdený
s9hts: příkaz nenalezen
s9hts: команда не найдена
s9hts: командата не е открита
s9hts: 命令找不到
s9hts: コマンドが見つかりません