lcm-gen: 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/lcm-gen - from package: lcm

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

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