Hello is there a way to open commandblocks and read whats typed in the command line if so how can i do this? sorry for bad english
You can no longer force open the command block GUI as of 1.8. However, you can still get the input from the custom payload packet with tag MC|AdvCmd.
Alternative, somewhat full answer (excerpts from my Consoles project): https://gist.github.com/wacossusca34/36a82d097f7fb9c926c8 No packet handling here, instead I go right after the command block's tile entity in NMS code - this way we can effectively listen for commands the same way the server does (via redstone, etc), set the output, or just read input when it's changed. You can also add custom vanilla commands with this, which allow for commands built specifically for command blocks. Admittedly this is insanely complex in comparison to just listening for a packet, but you actually get to access the data (and methods) that the command block holds instead of just grabbing info from packets. You cannot open a command block GUI for a client, though, like DarkSeraphim pointed out.
