dfg2otter: 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/dfg2otter - from package: spass

You may install the required package with command apt-get install {package}
Error in other languages:
dfg2otter: bevel nie gevind nie
dfg2otter: comandă negăsită
dfg2otter: comando não encontrado
dfg2otter: commande introuvable
dfg2otter: command not found
dfg2otter: käsku ei ole
dfg2otter: không tìm thấy lệnh
dfg2otter: komanda nerasta
dfg2otter: Kommando nicht gefunden.
dfg2otter: kommandot finns inte
dfg2otter: komut yok
dfg2otter: nie znaleziono polecenia
dfg2otter: níor aimsíodh an t-ordú
dfg2otter: no se encontró la orden
dfg2otter: no s'ha trobat l'ordre
dfg2otter: opdracht niet gevonden
dfg2otter: parancs nem található
dfg2otter: perintah tidak ditemukan
dfg2otter: príkaz nenájdený
dfg2otter: příkaz nenalezen
dfg2otter: команда не найдена
dfg2otter: командата не е открита
dfg2otter: 命令找不到
dfg2otter: コマンドが見つかりません