semodule_link: 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/semodule_link - from package: policycoreutils

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

On Debian possible default full paths are:

/usr/bin/semodule_link - from package: policycoreutils

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

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