plxload: 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/plxload - from package: perl-pmtools

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

On Debian possible default full paths are:

/usr/bin/plxload - from package: pmtools

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

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