plum: 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/plum - from package: plum

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

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