sechecker: 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/sechecker - from package: setools-console

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

On Debian possible default full paths are:

/usr/bin/sechecker - from package: setools

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

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