pmlock: 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/pmlock - 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/pmlock - from package: pcp

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

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