defectDensity: 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/defectDensity - from package: findbugs

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

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