mongoperf: 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/mongoperf - from package: mongodb

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

On Debian possible default full paths are:

/usr/bin/mongoperf - from package: mongodb-clients

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

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