blockfinder: 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/blockfinder - from package: blockfinder

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

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