kde-open: 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/kde-open - from package: kdebase-runtime

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

On Debian possible default full paths are:

/usr/bin/kde-open - from package: kde-runtime

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

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