pamx: 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/pamx - from package: netpbm-progs

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

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