sdf: 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/sdf - from package: sdf

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

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