cannakill: 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/sbin/cannakill - from package: Canna

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

On Debian possible default full paths are:

/usr/bin/cannakill - from package: Canna

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

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