Where is debug.log file in Bitcoin source code? I am running 64bit Ubuntu 17.04, I am following this tutorial for creating a new altcoin. I am up to section 7, here to be exact:

The first time you run the compiled code (daemon or qt), it will say "assertion failed". Just exit the program, go to
config dir (under AppData/Roaming), open the debug.log, get the hash after "block.GetHash() = ", copy and paste it to the beginnig of main.cpp, hashGenesisBlock. Also get the merkle root in the same log file, paste it to the ... position in the following code, in LoadBlockIndex()

I am struggling to find the debug.log file, and so cannot get my hashes to continue. This guide is quite old (4 years) and I think is for setting up an altcoin on Windows.

Where is my debug.log file? If it doesn't exist, what is my next step?
On Unix systems the debug.log file, as well as all other files created by the client (blockchain data, databases, etc) are placed by default in ~/.bitcoin; that is, a subdirectory of your home directory named .bitcoin.  If you have used -datadir to set a different data directory, debug.log will be placed there instead.

Note that the ls command normally will not show files or directories that start with ., so you won't see this if you just ls your home directory.  But you can still cd there, or use ls -a to see it.