POST: 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/POST - from package: perl-libwww-perl

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

On Debian possible default full paths are:

/usr/bin/POST - from package: libwww-perl

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

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