bespp: 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/bespp - from package: mcrl2

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