sec: 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/sec - from package: sec

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

On Debian possible default full paths are:

/usr/bin/sec - from package: sec

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

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