ujdet: 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
/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/ujdet - from package: abinit

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