Are you getting these errors on Ubuntu?
>./bitcoin-qt
> permission denied
> sudo ./bitcoin-qt
> command not found
or the same with litecoin?
>./litecoin-qt
> permission denied
> sudo ./litecoin-qt
> command not found
First of all, let’s back track a bit. You have probably gone to https://bitcoin.org/en/choose-your-wallet or https://litecoin.org/ and chosen to download the core binaries.
There are 2 options in fact. You could install the binaries themselves (ie the application) or download the source code and rebuild to the binaries. Let’s look at installing the binaries. In windows, you do your normal install by clicking on the .exe and watch it install. In Linux/Ubuntu though you just plonk the tgz file somewhere and extract it. Then you navigate to the location and try to run it by typing the commands above.
The first error, “permission denied” means that you do not have permission to execute the file. You need to run this command:
chmod +x bitcoin-qt or chmod +x litecoin-qt
This will solve the first problem. The next is the command not found. You should be able to type “./bi” and then tab to get auto complete to kick in. If not, copy the bitcoin directory somewhere in your home directory. ie if you have multiple hard drives and place the file there, you will get this error. That should do it.
References:
* https://bitcointalk.org/index.php?topic=658972.0