checkmodule: 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/checkmodule - from package: checkpolicy

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

On Debian possible default full paths are:

/usr/bin/checkmodule - from package: checkpolicy

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

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