setxkbmap: 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/setxkbmap - from package: xorg-x11-xkb-utils

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

On Debian possible default full paths are:

/usr/bin/setxkbmap - from package: x11-xkb-utils

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

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