funionfs: 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/funionfs - from package: funionfs

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

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