qxkb: 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/qxkb - from package: qxkb

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

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