nautilus-compare-preferences: 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/nautilus-compare-preferences - from package: nautilus-compare

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

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