uml_moo: 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/uml_moo - from package: uml_utilities

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

On Debian possible default full paths are:

/usr/bin/uml_moo - from package: uml-utilities

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

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