pmstat: 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/pmstat - from package: pcp

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

On Debian possible default full paths are:

/usr/bin/pmstat - from package: pcp

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

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