pmnewlog: 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/pmnewlog - 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/pmnewlog - from package: pcp

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

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