startkde: 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/startkde - from package: kdebase-workspace

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

On Debian possible default full paths are:

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

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

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