pmproxy: 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/libexec/pcp/bin/pmproxy - from package: pcp

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

On Debian possible default full paths are:

/usr/lib/pcp/bin/pmproxy - from package: pcp

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

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