monkeysphere-authentication: 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 CentOS possible default full paths are:

/usr/sbin/monkeysphere-authentication - from package: monkeysphere

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/sbin/monkeysphere-authentication - from package: monkeysphere

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

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