mcl: 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 Debian possible default full paths are:

/usr/bin/mcl - from package: mcl

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

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