fog: command not found

Have You tried accessing the binary with the full path?

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/fog - from package: gnudos

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

On Debian possible default full paths are:

/usr/bin/fog - from package: ruby-fog

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