Preview: 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/Preview - from package: preview.app

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

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