moncmd: 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/moncmd - from package: mon

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

On Debian possible default full paths are:

/usr/bin/moncmd - from package: mon

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

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