grpmorphan: 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/grpmorphan - from package: rpmorphan

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

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