I\'m on OSX and I need to put something like this, alias blah=\"/usr/bin/blah\" in a config file but I don\'t know where the config file is.
Apple switched their default shell to zsh, so the config files include ~/.zshenv and ~/.zshrc. This is just like ~/.bashrc, but for zsh. Just edit the file and add what you need; it should be sourced every time you open a new terminal window:
nano ~/.zshenv
alias py=python
Then do ctrl+x, y, then enter to save.
This file seems to be executed no matter what (login, non-login, or script), so seems better than the ~/.zshrc file.
The default shell is bash, and you can edit the file ~/.bash_profile and add aliases:
nano ~/.bash_profile
alias py=python
Then ctrl+x, y, and enter to save. See this post for more on these configs. It's a little better to set it up with your alias in ~/.bashrc, then source ~/.bashrc from ~/.bash_profile. In ~/.bash_profile it would then look like:
source ~/.bashrc