git

Different from SVN
It is important to note that this is very different from most SCM systems that you may be familiar with. Subversion, CVS, Perforce, Mercurial and the like all use Delta Storage systems - they store the differences between one commit and the next.
Git does not do this - it stores a snapshot of what all the files in your project look like in this tree structure each time you commit. This is a very important concept to understand when using Git.
Git’s pack files are carefully constructed to effectively use disk caches and provide “nice” access patterns for common commands and for reading recently referenced objects.

https://github.blog/2019-08-16-highlights-from-git-2-23/

You may have used git grep to search for some text in your Git project, just as you may have used git diff to view active changes. What do the two have in common? They both display some contents in your repository, and both have support to show the surrounding function context with -p (short for --show-function) or -W (short for --function-context), respectively.

Configure your git blame to ignore cleanup changes.

https://www.moxio.com/blog/43/ignoring-bulk-change-commits-w…

https://lobste.rs/s/e3blgf/fossil_versus_git

This article is getting a few things about git wrong. They claim git only supports ‘One check-out per repository’. Heard of git worktree?

Git revise is especially useful for this commit stack workflow, as I call it. I’m a huge fan.

It’s a better rebase. So much better that it should be obligatory. You can split commits, batch rename them, and you don’t have to stash your work first.

wsdiff
image diff
nbstirpout
iadd
extra worktree dir

I’ve written up my ideas, under the name ‘Literate Git’, at https://github.com/bennorth/literate-git if you’re interested.
The tool I wrote turns a structured git history into an interactive web page.
There’s an example there of how the ideas might work in a tutorial setting.
After I gave a talk on this work, one of the people in the audience tried it with the Haskell LLVM tutorial: https://lukelau.me/kaleidoscope/

https://stackoverflow.com/questions/1260748/how-do-i-remove-a-submodule/21211232#21211232

git rm the_submodule
rm -rf .git/modules/the_submodule

https://stackoverflow.com/questions/7375528/how-to-extract-one-file-with-commit-history-from-a-git-repo-with-index-filter/37037151

git filter-branch --index-filter 'git read-tree --empty; git reset $GIT_COMMIT -- $your $files $here' -- --all --

for an academic treatment of the defects in Git read: What's Wrong with Git? A Conceptual Design Analysis S. Perez De Rosso and D. Jackson. In Proceedings of the 2013 ACM International Symposium on New Ideas, New Paradigms, and Reflections on Programming & Software (Onward! 2013) 

for r in *; do pushd $r; git whatchanged | grep "\.\.\..T"; popd; done

GIT_SSH_COMMAND='ssh -v' git fetch

For archeology I really love git gui blame despite its dated UI

he majority of answers to this question are outdated, incomplete, or unnecessarily complex.

A submodule cloned using git 1.7.8 or newer will leave at most four traces of itself in your local repo. The process for removing those four traces is given by the three commands below: