kni_interlink: 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_interlink - from package: libkni3-examples

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

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