yesod init is not working

edit

I know nothing about yesod, but the most likely reasons are:

• the binary/executable is not called yesod in which case you need to identify the correct executable name - there may be other ways, but sudo find / -iname '*yesod*' would do as a fairly crude mechanism.
• the executable is not in your $PATH - if you can locate it (see previous step), then add it to your .bash_profile file;

echo 'PATH=$PATH:/path/to/yesod; export $PATH' >> ~/.bash_profile

snowolfe is correct you need to update your path, but it's the path for cabal. Which should be

PATH=$PATH:$HOME/.cabal/bin

You might also want to checkout stack. It has really good documentation and is a bit more user friendly.