lgroupmod: 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/lgroupmod - from package: libuser

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

On Debian possible default full paths are:

/usr/sbin/lgroupmod - from package: libuser

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

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