kbd-layout-viewer: 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 Debian possible default full paths are:

/usr/bin/kbd-layout-viewer - from package: kde-config-fcitx

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

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