grep-merges: 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/grep-merges - from package: ubuntu-dev-tools

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

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