modulecmd: 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/modulecmd - from package: environment-modules

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

On Debian possible default full paths are:

/usr/bin/modulecmd - from package: environment-modules

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

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