nymerge: 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 CentOS possible default full paths are:

/usr/bin/nymerge - from package: patchy

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/nymerge - from package: nypatchy

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

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