fvfuseviewer: 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/fvfuseviewer - from package: fawkes-guis

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

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