nautilus: 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/nautilus - from package: nautilus

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

On Debian possible default full paths are:

/usr/bin/nautilus - from package: nautilus

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

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