flawfinder: 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/flawfinder - from package: flawfinder

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

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