kni_perfo: 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/kni_perfo - from package: libkni3-examples

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

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