gupta-abhay/Torch installation Error and Debug.md

## Torch installation Error and Debug.md

      
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              Torch installation Error and Debug.md
            
          
    #Dependency Bug Fix for nn package torch
(Note: This is the bug-fix i could found. If you find an easier way, please let me know in the comments below.)

During installation of torch on your computer or the GPU, you may possibly encounter a bug similar to this one:
Dependency missing for nn:
luaffi

Installing https://raw.githubusercontent.com/torch/rocks/master/luaffi-scm-1.rockspec ... switching to build mode

fatal error: unable to access 'https://raw.githubusercontent.com/torch/rocks/master/luaffi-scm-1.rockspec'
github.com: Could not resolve host 'github.com'

Installation failed

To fix the bug

Perform a clean by running sh clean.sh
If you run into Permission denied errors then, use sudo sh clean.sh, but necesarily make sure the previous installation is cleaned
Switch directories cd ~/torch/extra/luaffib and then run ~/torch/install/bin/luarocks make
Again if you face Permission denied error, then run sudo ~/torch/install/bin/luarocks make 
The main resaon for using ~/torch/install/bin/ is because:

LuaJIT21 is installed in the first step of the build process
It is built directly into /usr/local/lib/luarocks
If ~/torch/install/bin/luarocks is not specified, the build is lost to the torch install.sh file


After doing this, go to ~/torch/install/lib/luarocks/rocks and check if the folder luaffi is built.

If yes, you are covered and can perform a clean install.
Else, run sudo sh clean.sh again in the base torch folder and re-build it.


Now, switch to ~/torch/ and then run install.sh once again.

Remember to run sudo ~/.bashrc or sudo ~/.profile for refreshing your environment variables.
Now, run th and you should get a display like the one shown here.
Congratulations!!! You have successfully installed Torch.