ladr_to_tptp: 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/ladr_to_tptp - from package: ladr4-apps

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

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