srtm2sdf: 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/srtm2sdf - from package: splat

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

Error in other languages:
srtm2sdf: bevel nie gevind nie
srtm2sdf: comandă negăsită
srtm2sdf: comando não encontrado
srtm2sdf: commande introuvable
srtm2sdf: command not found
srtm2sdf: käsku ei ole
srtm2sdf: không tìm thấy lệnh
srtm2sdf: komanda nerasta
srtm2sdf: Kommando nicht gefunden.
srtm2sdf: kommandot finns inte
srtm2sdf: komut yok
srtm2sdf: nie znaleziono polecenia
srtm2sdf: níor aimsíodh an t-ordú
srtm2sdf: no se encontró la orden
srtm2sdf: no s'ha trobat l'ordre
srtm2sdf: opdracht niet gevonden
srtm2sdf: parancs nem található
srtm2sdf: perintah tidak ditemukan
srtm2sdf: príkaz nenájdený
srtm2sdf: příkaz nenalezen
srtm2sdf: команда не найдена
srtm2sdf: командата не е открита
srtm2sdf: 命令找不到
srtm2sdf: コマンドが見つかりません