pmmgr: 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/pmmgr - from package: pcp-manager

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

On Debian possible default full paths are:

/usr/lib/pcp/bin/pmmgr - from package: pcp-manager

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

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