kquitapp: 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/kquitapp - from package: kdebase-runtime

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

On Debian possible default full paths are:

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

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

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