fvwm-crystal.videomodeswitch+: 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/fvwm-crystal.videomodeswitch+ - from package: fvwm-crystal

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

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