gfan_fansubfan: 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/gfan_fansubfan - from package: gfan

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

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