defaults: 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/defaults - from package: gnustep-base

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

On Debian possible default full paths are:

/usr/bin/defaults - from package: gnustep-base-runtime

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

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