greenwich: 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/greenwich - from package: greenwich

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

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