greekocr4gamera: 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/greekocr4gamera - from package: python-gamera.toolkits.greekocr

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

Error in other languages:
greekocr4gamera: bevel nie gevind nie
greekocr4gamera: comandă negăsită
greekocr4gamera: comando não encontrado
greekocr4gamera: commande introuvable
greekocr4gamera: command not found
greekocr4gamera: käsku ei ole
greekocr4gamera: không tìm thấy lệnh
greekocr4gamera: komanda nerasta
greekocr4gamera: Kommando nicht gefunden.
greekocr4gamera: kommandot finns inte
greekocr4gamera: komut yok
greekocr4gamera: nie znaleziono polecenia
greekocr4gamera: níor aimsíodh an t-ordú
greekocr4gamera: no se encontró la orden
greekocr4gamera: no s'ha trobat l'ordre
greekocr4gamera: opdracht niet gevonden
greekocr4gamera: parancs nem található
greekocr4gamera: perintah tidak ditemukan
greekocr4gamera: príkaz nenájdený
greekocr4gamera: příkaz nenalezen
greekocr4gamera: команда не найдена
greekocr4gamera: командата не е открита
greekocr4gamera: 命令找不到
greekocr4gamera: コマンドが見つかりません