mpstat: 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/mpstat - from package: sysstat

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

On Debian possible default full paths are:

/usr/bin/mpstat - from package: sysstat

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

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