gcb: 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/gcb - from package: gcb

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

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