k5start: 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/k5start - from package: kstart

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

On Debian possible default full paths are:

/usr/bin/k5start - from package: kstart

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

Error in other languages:
k5start: bevel nie gevind nie
k5start: comandă negăsită
k5start: comando não encontrado
k5start: commande introuvable
k5start: command not found
k5start: käsku ei ole
k5start: không tìm thấy lệnh
k5start: komanda nerasta
k5start: Kommando nicht gefunden.
k5start: kommandot finns inte
k5start: komut yok
k5start: nie znaleziono polecenia
k5start: níor aimsíodh an t-ordú
k5start: no se encontró la orden
k5start: no s'ha trobat l'ordre
k5start: opdracht niet gevonden
k5start: parancs nem található
k5start: perintah tidak ditemukan
k5start: príkaz nenájdený
k5start: příkaz nenalezen
k5start: команда не найдена
k5start: командата не е открита
k5start: 命令找不到
k5start: コマンドが見つかりません