mcd: 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/mcd - from package: mtools

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

On Debian possible default full paths are:

/usr/bin/mcd - from package: mtools

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

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