pmatop: 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/pmatop - from package: pcp-system-tools

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

On Debian possible default full paths are:

/usr/bin/pmatop - from package: pcp

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

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