monkeysign: 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/monkeysign - from package: monkeysign

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

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