tptp_to_ladr: 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/tptp_to_ladr - from package: ladr4-apps

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

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