Go back in time thanks to GIT. What if you would like to go back in time in the code and find that specific version of the code: you need to first find the corresponding commit and then checkout to that specific commit. See more doc here.
On Macs, whenever you modify the metadata of a directory (e.g., should it be displayed as thumbnails or as a list?), a .DS_Store hidden file will be created. Very annoying. Use the following alias! When running this in a directory, all .DS_Store files in the directory and subdirectories will be removed.
alias unshite="find . -name '*.DS_Store' -type f -delete"