plowdown: 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/bin/plowdown - from package: plowshare

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

On Debian possible default full paths are:

/usr/bin/plowdown - from package: plowshare4

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

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