fvshowyuv: 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/fvshowyuv - from package: fawkes-guis

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

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