Remember that Linux is not as forgiving as Windows is, case matters
Copy and Paste this:
./cod4_lnxded +set fs_homepath /home/cod4_test +set dedicated 2 +set sv_maxclients 5 +set ui_maxclients 5 +set fs_game mods/x4v30 +exec server.cfg +set sv_punkbuster 0
Change your folder X4v3.0 to x4v30 -- also you don't need +map mp_killhouse in your rotation with our mod, our config/maprotation.cfg takes care of that for you