mco: 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/sbin/mco - from package: mcollective-client

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

On Debian possible default full paths are:

/usr/bin/mco - from package: mcollective-client

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

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