fbi: 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/fbi - from package: fbida

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

On Debian possible default full paths are:

/usr/bin/fbi - from package: fbi

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

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