kstartupconfig4: 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/kstartupconfig4 - from package: kdebase-workspace

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

On Debian possible default full paths are:

/usr/bin/kstartupconfig4 - from package: kde-workspace-bin

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

Error in other languages:
kstartupconfig4: bevel nie gevind nie
kstartupconfig4: comandă negăsită
kstartupconfig4: comando não encontrado
kstartupconfig4: commande introuvable
kstartupconfig4: command not found
kstartupconfig4: käsku ei ole
kstartupconfig4: không tìm thấy lệnh
kstartupconfig4: komanda nerasta
kstartupconfig4: Kommando nicht gefunden.
kstartupconfig4: kommandot finns inte
kstartupconfig4: komut yok
kstartupconfig4: nie znaleziono polecenia
kstartupconfig4: níor aimsíodh an t-ordú
kstartupconfig4: no se encontró la orden
kstartupconfig4: no s'ha trobat l'ordre
kstartupconfig4: opdracht niet gevonden
kstartupconfig4: parancs nem található
kstartupconfig4: perintah tidak ditemukan
kstartupconfig4: príkaz nenájdený
kstartupconfig4: příkaz nenalezen
kstartupconfig4: команда не найдена
kstartupconfig4: командата не е открита
kstartupconfig4: 命令找不到
kstartupconfig4: コマンドが見つかりません