conmen: 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/conmen - from package: conman

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

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