gocr-tk: 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/gocr-tk - from package: gocr-tk

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

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