sdr2file: 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/sdr2file - from package: ion

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

Error in other languages:
sdr2file: bevel nie gevind nie
sdr2file: comandă negăsită
sdr2file: comando não encontrado
sdr2file: commande introuvable
sdr2file: command not found
sdr2file: käsku ei ole
sdr2file: không tìm thấy lệnh
sdr2file: komanda nerasta
sdr2file: Kommando nicht gefunden.
sdr2file: kommandot finns inte
sdr2file: komut yok
sdr2file: nie znaleziono polecenia
sdr2file: níor aimsíodh an t-ordú
sdr2file: no se encontró la orden
sdr2file: no s'ha trobat l'ordre
sdr2file: opdracht niet gevonden
sdr2file: parancs nem található
sdr2file: perintah tidak ditemukan
sdr2file: príkaz nenájdený
sdr2file: příkaz nenalezen
sdr2file: команда не найдена
sdr2file: командата не е открита
sdr2file: 命令找不到
sdr2file: コマンドが見つかりません