undertaker-kconfigpp: 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/undertaker-kconfigpp - from package: undertaker

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