flappserver: 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/flappserver - from package: python-foolscap

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

On Debian possible default full paths are:

/usr/bin/flappserver - from package: python-foolscap

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

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