plainbox: 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/plainbox - from package: plainbox

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

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