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Flight rules for Git (github.com)
203 points by spenrose on Oct 16, 2018 | hide | past | favorite | 131 comments

It never ceases to amaze me that:

1. Git, a software product with more footguns per square inch of user-exposed surface than any I've ever encountered, ended up winning the distributed VCS sweepstakes; and

2. Even now, more than five years after it was clear to everyone that Git had won, there is absolutely no momentum to go back and clean it up to remove any of those footguns. All we get instead are increasingly shiny GUIs to hide them under, and well-meaning blog posts advising you on which is the best kind of tourniquet to apply when you trigger one of the aforementioned footguns.


Honestly have found it nothing but a pleasure to use. Not at all upset by the UI. It’s fine. Hg is fine. They’re easy enough to use that I never think about it and I rebase interactive daily and am comfortable with the reflog. It surprisingly didn’t take that long.

I’ve never found myself backed into a corner and I suspect this is part of its success: some people have codebases where it’s a problem (branch names which are files, for instances) but most people don’t encounter this sort of thing and it works just fine.

It’s basically a manifestation of programmer arrogance that they’re just too damn smart to encounter a software learning curve again.

Ever sat through user training on microsoft office? How to use email? The weird one-off enterprise apps that nobody else has ever heard of?

They’re unbearably tedious to users that can get by in a new tool with a 5 minute crash course, intuition and light googling.

Then git shows up and has the audacity to ask professionals to learn its mental model.

Once you do the interface isn’t great, but not particularly esoteric. The problem isn’t that users see dense-sounding things like “directed acyclic graph of revisions”, it’s that they assume they can competently manipulate one without knowing what that means.

I do think the interface could use cleanup, but can any ammount of cleanup prevent needing to know the mental model of git?

Bullshit. The "mental model" has never been the issue with git, it's always been that the UI is garbage and a giant abstraction leak, requiring knowing the implementation details of the commands and the storage model to work with and step over footguns. Because rather than an actual, designed, considered UI, the porcelain is crummy shortcuts on sets of operations on the underlying storage (not mental) model.

Mercurial has the same "DAG of revisions" model as git, and works just fine, because it has a good UI.

Darcs has a more unusual mental model than git, and works just fine, because it has a good UI.

> Mercurial has the same "DAG of revisions" model as git, and works just fine, because it has a good UI.

People keep saying this, and this keeps not matching my experience of helping people with VCS issues at Mozilla.

Mercurial's model is roughly "append only list of commits, that separately form a DAG". This list model is leaked all over the place. For example the default `hg log` view just dumps that list rather than telling you anything about the history of the current working copy. To get that you need to add -f, which of course in most contexts means "do something unsafe". Worse, the list model is exposed in the local revision ids, which are prominently presented in the UI, and users have to learn that these ids aren't sharable with other users when discussing a revision. Also the most prominent "symbolic ref" in mercurial is "tip" which means "commit at the last position in the internal list", and so is sometimes the current head, and other times is some random commit from the remote.

Giving people help in mercurial is also super-challenging because, unless you are in some controlled environment, the first question is always "which extensions do you have enabled" and for complex tasks the next step is often "you should enable and learn to use <some extension>".

Which isn't to say that Mercurial is overall particuarly bad. There are some areas in which it's really an improvement over git (revset specifiers are pretty awesome, for example). But I often feel like praise for the UI comes from people who have internalised its flaws, and is repeated by people who haven't actually used it, but dislike git and are happy to accept something that confirms their preconceptions.

The biggest leaking abstraction of git IMO, are commits: they equate a set of changes with the state of the repo after said changes. So if there are multiple commits, reverting a commit is ambiguous. Does it revert the state of the repository to the state before the commit, or does it revert the changes in the commit?

There are a couple more flaws. The commandline is not very consistent, and the complete model is way too complicated IMHO. I can work with it now, but it took me a long time to grasp all of the concepts that I need - without feeling the need for distibuted version control. About that: It's kind of ironic that git is hailed for being distributed, but everyone just uses github, a centralized system.

Just to be pedantic, a commit is actually "the state of the repo after said changes" plus "the commit(s) before said changes" (which allows one to recover the "set of changes" by comparing the before/after states).

I don't think that's true. At least, not if you revert something - it reverts only the changes introduced in that commit. (That there is confusion - or even discussion possible - is exactly my point: the abstraction is leaky at worst, and confusing at best).

Edit: You're right, but my point was that the revert command treats a commit like a set of changes, not like the state of of a repo (since you can't revert the state of a repo, but you can revert changes).

See for yourself: do a "git cat-file commit HEAD" on any repository. The "tree" line is the current state, the "parent" line(s) are the preceding commit(s). That command shows everything git has recorded for any commit (you can similarly use "git ls-tree <sha1>" to show everything git has recorded for any tree, or "git cat-file blob <sha1>" to show the contents of a file from the tree).

You're right from a technical perspective. What I meant that as an abstraction, it serves a double purpose (it represents both a node and an edge in the DAG, and it depends on the command that you use which interpretation is right).

If you checkout a commit, the commit represents the state of the repository. If you revert a commit, the commit represents a set of changes.

> I do think the interface could use cleanup, but can any ammount of cleanup prevent needing to know the mental model of git?

Git's interface is far, far more complicated than its model. Personally I spent years not learning about the model because I thought it would be as complicated as the interface. When I realised that the model is basically as simple as what you get when you view the "network" on GitHub then I started loving Git.

Exactly this. Git is pretty easy; at the same time, using Git isn't. If you skip learning the easy mental model, all you have left is hard interface, so in result you just struggle, because you can't even rely on your intuition to get how things work there.

I've found that adding my own aliases that sound more akin to what I'm trying to achieve has helped greatly with this, e.g. I have 'discard' as an alias for 'checkout --'.

> It’s basically a manifestation of programmer arrogance that they’re just too damn smart to encounter a software learning curve again.

It's fun to be cynical, but surely this is just yet another example of how hard it is to "just change" something for all sorts of reasons.

It's funny that you bring up hubris when the pinnacle of developer hubris is "surely it can't be too hard to {build it, change it, replace it} -- I could do it!"

Conversely, no other industry places so much focus on making sure that tools for professionals are easy for beginners to use, often at the expense of features.

What 'footguns' are there? I find it pleasingly hard to accidentally delete anything, or get myself into any kind of corner when using Git. What am I missing?

Consider `git checkout` and having a file called `master` at the root level of the repo.

Further, what does `git checkout a/b` do?

* Checkout a file called a/b

* Checkout branch b from remote a

* Checkout a local branch called a/b

I've seen people end up with local branches with names like 'upstream/mybranch', then get super-confused about how these branches aren't "upstream". git should really ban local branches with a / in their name.

It's a bug that "git checkout" does not complain in this case. I'll try to fix or report it.

Though I agree with you, a warning could be issued.

Sounds like an edge case. This isn’t really a problem with Git per se.

A single command doing two completely different things arbitrarily depending on file matches isn't an "edge case".

But this very common for many tools:

  touch -- -l
  ls *

However, if you run both commands consistently, nothing untoward occurs:

  touch -- -l
  ls -- *
The fact that you have to use a double-hyphen flag to create a file with a name starting with a hyphen is a strong indication that this situation is an edge case.

And git handles the edge case the same way. That was my point.

  rm master
  git checkout -- master
  git checkout a1b1
  git checkout master -- master
all works as expected

Not quite. I believe the point is that it's not an edge case, since "master" isn't a particularly unusual name, not in the Unix tradition, nor, AFAIK, on any other OS.

You'll note that, for example, your "rm" didn't require a double-hyphen.

The OC's point (and maybe the GP's point [1]), ultimately, is about git command syntax ambiguity. With traditional Unix commands, there's not much ambiguity. At worst, there's merely no obvious way to pass an argument that's a filename starting with a hyphen. The question "what does 'ls -l' do?" would not plausibly have an answer of "output '-l' if a directory entry with that name exists" in addition to "output a long listing of all directory entries".

[1] Does git actually behave differently based on the existence of a directory entry named "master" or does it merely require extra effort to work with such an entry, which would actually be directly analagous to filenames beginning with a hyphen?

That's bad too.

Explain detached head like i’m 5 years old.

Detached HEAD isn't complicated. It simply means there is nothing tracking the current line of work beyond the commit shas themselves. No branch is updated when you make commits.

Conversely, attached HEAD means a branch is being updated whenever you make a commit, e.g. when you make commits on your local master.

Oh, I see. I created this great patch and commited it. Then I wanted to push it, but it reported some strange error.

I checked out master but now my commit is no longer there. HELP!

Can I somehow push my changes to you so you can fix it?

Ah let's intuitively try:

git log --graph --decorate $(git rev-list -g --all)

For comparisson:

- mercurial would show your commit all the time, no matter what currently is checked out.

- Only when you push, you have to force it, to create a new head in the remote repository because most workflows expect you to merge heads locally.

All I get from this comment is that "git reflog" should be one of the first things taught about git :P

Maybe reflog would help. Unfortunately most cheat sheets I saw don't mention it.

As other comments here have suggested, git cheatsheets should be ignored if you are learning git.

But why would I get into that state, and how do I get out without losing my work? Neither of those is obvious.

> how do I get out without losing my work?

When you move out of detached head state by checking out another branch Git tells you how to save your work to a branch.

It could usefully say that when you do a “git status” when you’re in a detached state, instead of just saying “detached HEAD” and expecting you to figure it out (or google for it).

It could very usefully try harder to avoid getting into that state in the first place.

>It could very usefully try harder to avoid getting into that state in the first place.

Am I missing something here? How do you get into a detached HEAD state without explicitly taking an obviously weird action, like finding and checkout out a commit hash instead of a branch, and why would it make sense for git to not be in a detached HEAD state should you do that?

Imagine someone does task X but they do it very poorly and in master. You want to get rid of their last few commits (without a force push).

Most people don't think about doing a hard reset to the last good commit, and then soft resetting to HEAD~. Instead, they just "git checkout $LAST_GOOD_COMMIT". And afterwards they may even continue by working with a detached HEAD

> an obviously weird action, like finding and checkout out a commit hash instead of a branch

But this isn't an obviously weird action? It happens all the time when you need to branch off from a previous point.

Maybe you're unexpectedly releasing a hotfix, maybe your current development is going in a bad direction, maybe you need to test something against a previous state.

Rebase has several cases that will drop you into a detached HEAD. Rebase has gotten better at warning you when it is happening, and much better at telling you what your next steps are in that situation (such as git rebase abort), at least, but it still does it.

Several times that I've helped junior developer out of a detached HEAD state, when I asked what they thought they were doing before it happened, the answer was "I was just doing my normal rebase before..."

It is (or at least used to be) pretty easy to end up with a detached HEAD when working with submodules and aren't sure what you are doing. It definitely didn't need an "obviously weird" action.

> It could usefully say that when you do a “git status” when you’re in a detached state

That's a great idea and it really confuses me why they don't add obviously useful things to the interface.

Why should he have to? It's irrelevant to the point he's making, since a tool being conceptually difficult is not the same thing as it having footguns.

> a tool being conceptually difficult is not the same thing as it having footguns.

But the tool is not conceptually difficult. All the difficulty of git is in the trap its "UI" creates for no reason. The concepts are easy. I taught Darcs to a frontend/flash developer 15 years ago, and it's not because I'm a great teacher.

I get that could be confusing, but there's no 'gun' there, is there? You may have to move your commit, but nothing been damaged?

Time wasted is equivalent to damage.

Every digital damage can be undone by wasting enough time.

If you're in detached head then `checkout -b the_detached_head_i_just_had` and the fact that you were in detached head becomes irrelevant.

Maybe five year olds shouldn't be mucking with your source code.

Detached is just that: you can party on it all you want, but it's not going to go anywhere when you commit unless you go out of your way.

One consolation with Git, you know it is almost always possible to recover from any mistake. Theoretically anyway. I think we've all been in that situation where a team of engineers are huddling round a monitor strategizing about just how to undo the snafu of the day, brainstorming increasingly extreme solutions.

You're probably right. I, though, know just enough GIT to get by. In every case where things have gone seriously pear-shaped, it's just quicker -- like days quicker -- for me just to throw everything to the wind and clone the repo again. Reading up how to do the proper thing a recover will just take me order-of-magnitude longer, and frankly, I don't have the time.

Just think how many person-hours were wasted by that team huddled around the monitor...

GIT: The Swiss-Army Chainsaw of Version Management.

Once you understand a few basic things like the underlying git model, and what the reflog is, you can basically get out of any situation. Totally worth the time to learn, it'll save you a ton of time

The interface should be what saves a ton of time, and should not expose the underlying technical model (especially because that model may change at some point)

I don't think it's reasonable at this point that git's underlying model ever changes substantially. Essentially, it is the interface that's stable over time.

It's also the easiest way to understand git.

You could learn to read by memorizing the shapes of thousands of words without learning the alphabet or how it matches up to sounds. I'm sure people have done it. But the failure mode when encountering a new word is complete and utter bewilderment that this new shape is unfamiliar, rather than a graceful degradation you get if you understand the alphabet. The same is true of git.

This is funny because the lack of consistency in Git's user interface forces you into memorizing the shapes of specific words (commands and arguments). To spell it's language.

The UI does a remarkably good job of hiding the elegant underpinnings from you.

> it's just quicker -- like days quicker -- for me just to throw everything to the wind and clone the repo again

In this case, I have a single suggestion for you: Give the following extra arguments to git clone.

  --reference /path/to/existing/clone/ --dissociate
This will download objects from your existing clone rather than from the remote repository, thus saving you a great deal of bandwidth if your repo is appreciably large. Also, this operation is absolutely safe. It will only copy objects over into the new clone that are referenced in the remote repository.

Every time I start to dig super deep on problems like this I stop for a second and wonder "just how important is it I fix this error" and "can this be solved by just paving over my local and reapplying my changes...". Most of the time the answer is not extremely and yes.

It's true that for any given problem, learning how to fix it probably isn't worth the time. I've found the long-term benefits of taking the time to learn how to fix every problem I've run into (and importantly, understand what the things I'm doing to fix it do) to be very worth it, though. Over time I've had to google how to do fewer and fewer things, and when I do still need to google something it takes me much less time to understand the answer and how to apply it.

As a polygot developer working in multiple languages, editors and ecosystems, git has been the one tool that I'm always using, and that makes it always worth investing more time into learning how to use it better.

Same really. I'm considered a "git expert" at work and the extent of my expertise is:

"This merge went completely sideways. But I haven't pushed anything."

"Okay, do this to export the commits you made as a patch file. Move those somewhere safe. Delete your repo. Reclone. Apply the patches. Commit. Start merge over again."

Also I can recognize whatever that weird error message is that means someone deleted a file in one branch and I edited it in another. Usually results in just "git rm (file); and git merge --continue".

> This merge went completely sideways.

  git merge --abort

Revision control, in general, turns 2D code into 3D code. Git turns 2D code into 4D code. With great power comes great responsibility. And you have to impose rules on yourself regarding which areas of that power landscape you should explore and which areas to stay away from (to keep your sanity, productivity, keep the complexity under control, etc, etc).

Flight rules, process workflows, protocols (both network protocols, and protocols of mission critical human activity), they all belong to the idea of limiting yourself to a set pattern of activity when dealing with something that can practically give you infinite possibilities. Because infinite possibilities give decision fatigue and analysis paralysis.

By 2D code I mean code in a text editor: the two dimensions of lines and columns.

By 3D code I mean: lines, columns, time (meaning commit timestamps)

By 4D code I mean: lines, columns, time, time travel (you can go back to older commits and rewrite your revision history).

But one of those shiny GUI was called GitHub, and it was the shiniest of the shiniest, so much that it make git usage ridiculously easy. At least on my experience.

Git is very easy to use, right up to the moment when it really really is not.

Every SCM/SCC/VCS has a wall you'll hit eventually. Whoopsie, the merge went wrong. Whoopsie, didn't mean to check that in. Whoopsie,... Most version control systems will allow you to crash through that wall with a little damage, might slow you down a little, but you'll keep going.

git's wall is thick, made of brick and reinforced concrete, and you'll be heading toward it at 200kph. You'll get going again eventually, once the metaphoric car gets glued back together.

Non-metaphorically, my experience has been that with SVN, Mercurial, et. al., a few quick web searches and I'm on my way. With git, "wait a minute...run that by me again?" I've used git for going on a decade, and now that I'm in an SVN shop I do sorely miss it. But, man, it's got some sharp edges.

I've never had to manually edit merge history in Git like SVN forces when merging complicated branch hierarchies. SVN is basically a half implemented VCS where the guts are exposed and you tread lightly whenever doing anything the original design didn't anticipate like ubiquitous merging.

This is a good metaphorical version of what it's like introducing new people to Git: https://www.youtube.com/watch?v=92wPOsuHZ9Y

GitHub really does nothing to make day-to-day usage of Git easy–it doesn't solve merge conflicts. It doesn't allow you to rebase commits. It doesn't find commits that you inadvertently wrote out of the branch. What it really does is provide a nice GUI around the current state of the repository and add some collaborative tools.

The big help for me at the time was the ease to navigate files accross merges, branches, commits, and share a specific point to anyone through a simple URL.

Up until this day navigating code feels more natural on the site that on native apps like sourcetree. I really miss the ease to see the same file from two different branches or commits, the feature might be there in native apps but I just couldn’t find it.

No, the shiny and efficient tool for daily git work is called magit, it runs on the Emacs platform (which also features a rather nice text editor).

> (which also features a rather nice text editor).

I know, right? This 'evil' thing is going places.

They're have been attempts at cleaning it up; cogito, tig, and gitless. Why they haven't caught on, we'll never know...

Because Linux, basically.

I was surprised there was no mention of how to get out of a HEAD detached state. That seems to be my number one "oops, now I've got to delete and re-clone" problem.

but... "git checkout master" and you are all done! why would you re-clone for that?

Can you give an example of a "footgun" that doesn't involve using a --force flag or "git reset --hard" without understanding what they do?

"No technology can ever be too arcane or complicated for the black t-shirt crowd." <- not really Linus but hey

Everyone talks about how confusing Git is, and I think it's because they do'nt understand what the commands do. Don't get me wrong: you can royally screw up your repository with the wrong command, but 85% of your issues can be solved with checkout, pull, add, commit, push, merge, reset, status, stash, branch. When things get really heavy you may have to use rebase. And in spite of what people say, there is a nifty log that's perfect for revisiting a snapshot of your CLI's action: reflog.

When I first started using Git, I was told, "When you want to make you commits public, use `git push -u origin <branch>` where branch the branch you're pushing to." That advice is technically correct, but I had no idea what -u nor origin was. I took 5 minutes to decipher the command. I walked away understand that origin an alias for the remote server, and that -u associates a remote branch with your local.

I don't think Git is the greatest thing ever. I do think there's a bit of a learning curve. I also think that it's not as complicated as people make it seem. This post is a great reference for how to do X in Git, but it's a terrible source for beginners learning how to use Git. Cheat sheets are most effective when you have a basic understanding of the material.

> Everyone talks about how confusing Git is, and I think it's because they do'nt understand what the commands do.

If nobody understands what the commands do, the problem is with the commands, not with the people.

It's not this simple. Git's porcelain is very unintuitive, but the underlying model is not. Once you understand the model, memorizing the commands is a relatively minor annoyance. But even if you fixed the porcelain there is essential complexity in understanding and utilizing the underlying model. To further clarify would require simplifying the model or features exposed, reducing the power of git as a tool.

There are those who say you should never rebase as a form of simplifying git, but people who follow that workflow have much much messier histories than those who know how to rebase properly. A well-curated history of well-explained atomic commits has incredible value, far outstripping the cost of maintenance on a long-lived project.

Git is a professional tool for software engineers, it has severe short-comings for non-coders, but as a software engineer learning it well will magnify your value.

If the Git developers have made an explicit decision that it's impossible to simplify the interfaces without losing some important functionality, hey, it's their software, that's their prerogative. But if that's the case, then people who have trouble understanding the interface shouldn't be called dumb, or chided for "not understanding the model," because it means the model is going to be too complicated for some people to understand.

Either Git is intended to be a tool anybody can pick up and use, in which case it's shameful how thoroughly ignored widespread complaints about the UI have been; or Git is intended to be a tool for a select priesthood of Enlightened Masters, in which case it shouldn't be promoted to the unwashed masses. You can't really have it both ways.

> Git is a professional tool for software engineers

Lots of tools for professionals of all kinds take the time to protect their users from inadvertently harming themselves through misuse. Cars for commercial drivers aren't sold with a set of wheel chocks in place of brakes, and if you argued that they should be because they're meant for professional drivers who ought to know better than to walk away from their vehicle without setting the chocks first, you'd earn yourself a lot of funny looks.

I got to "There are those who say you should never rebase as a form of simplifying git" and had to exert a lot of self control not to shout "YOU CAN PRY GIT REBASE INTERACTIVE OUT OF MY COLD DEAD HANDS!!"

I don't understand how anyone can live without rebasing their branch on master so their PR is a fast-forward merge and squashing their 4 days of WIP and Changing Computers commits into one sane commit.

Let's not even mention the fact that they introduce all those in-between commits where your unit testing is broken.

Our team has a very strict rule that every commit on master has passing unit tests and all merges to master (within reason) are fast-forward merges. We also allow force pushing to your feature branch to encourage using git as a decent backup for your WIP and eventually the cleanup before merging. As such, newbies get taught the basic rebase commands. This requires talking about the underlying model of git.

Git has a fair share of problems, but this command is not one of them.

`git push -u origin <branch>` requires you to to understand tree things: push, remotes, and branches. Once you know what those are the command is straightforward. Those concepts are very fundamental to any DCVS. Maybe you can do the first steps in other DCVS's without this knowledge * , but doing everything but the trivial things will require you to understand these concepts.

It's not strange that a tool solving a complicated problem for professional developers requires a bit of investment.

* But so you can in git, learning this command by rote is a valid strategy for a new git user.

> you can royally screw up your repository with the wrong command

You already mentioned the reflog, which makes Git screw ups a non-issue. But the only time I seriously messed up something was when I used Git commands without full understanding what they actually did (two weeks into learning Git). This was mitigated by RTFM, which clearly explained what I did wrong. Since then I never listen to advises like 'just use this git command', but read the manual first.

I noticed that most people who have problems with Git don't understand basic Git concepts like branch, remote, staging, commit, ref. These concepts are really not that hard. Once you get familiar with them everything else with Git is a breeze. But I'm surprised how stubborn people are at not willing to spend a little time to learn. They just want you to tell them Git commands. But Git commands are not important. I personally don't remember exact command parameters, because I can always look them up in the man page. Git concepts is what makes you proficient with Git.

I think you don't understand what the commands do.

Cheap jab aside, yeah git is fine 99% of the time. But that last 1% can really fuck you. 1% is not that small percentage.

I started version control with CVS. Just a bit better than copying.

I started distributed version control with monotone. That felt better but the central db felt a bit unnatural.

A bit later came mercurial and I was really happy with it. It all made sense. Easy interface and when you wanted to do something strange like rewrite history, you had to use a plugin.

Then came git (rhymes to better know your sh*t). I'm not surrounded by the smartest guys but most people I met only have a superficial understanding of git and looking at these flight rules kind of confirms the complexity of git.

I strongly believe that 80% of the current users of git would be better off with mercurial. But then everybody uses git for the remaining 20%.

>I strongly believe that 80% of the current users of git would be better off with mercurial.

I concur. I was in a team that needed to migrate away from SVN. I was already privately using mercurial while in the team. Jumping to git was too much for them in complexity. I tried convincing them that mercurial will give them almost all the benefits without the (needless) complexity, but they wouldn't listen and ended up using TFS.

Asking as someone who's never touched Mercurial: how is Mercurial simpler?

Looking at https://confluence.atlassian.com/get-started-with-bitbucket/..., the conceptual model looks almost identical, and so do the commands for common tasks.

git has 3+1 areas where a change can live:

  - working directory
  - staged 
  - commited
  - (upstream)
hg has only 2+1

  - working directory 
  - commited 
  - (upstream)
(*) both support something like stash but in hg it is easier to avoid that.

git log shows you history depending on the checked out version

hg log shows you the whole history of the branch, also after your checked out version. Knowing where you are is very valuable.

in hg you can push multiple heads into a repo. that is very convenient when a junior is unable to merge something. to my understanding in git you need different branches.

git - linus wants you to edit commits until they are perfect

hg - mpm once said that you have to accpet mistakes that happen[1]

as a consequence git has more advanced features very exposed while hg has a simple novice workflow

[1] https://www.mercurial-scm.org/pipermail/mercurial/2006-June/...

> (*) both support something like stash but in hg it is easier to avoid that.

Incidentally, using shelve in hg is the only way I've ever lost work in a VCS (I've made the same error in git as well, but a dropped stash can be found again).

> git log shows you history depending on the checked out version

> hg log shows you the whole history of the branch, also after your checked out version. Knowing where you are is very valuable.

git can show this, too, if you ask for it. If you've checked out some ancestor of `branch-name`, then `git log branch-name` will show `HEAD` next to the commit you've checked out. A single commit can belong to multiple branches, so if git showed you commits after your checked out version, which branch should it show? All of them?

> git - linus wants you to edit commits until they are perfect

You can use a never-rebase workflow in git as well, but most people elect not to.

> Incidentally, using shelve in hg is the only way I've ever lost work in a VCS (I've made the same error in git as well, but a dropped stash can be found again).

At least today there is


Mercurial doesn't have branches, right? That drove me bonkers when I was doing a bit of contract work after having used git for awhile.

edit: They must have been using a different SCM; ignore me!

Not only that it has branches -- it has four different ways to branch. http://stevelosh.com/blog/2009/08/a-guide-to-branching-in-me...

Of note: Git has 3 of those:

* git has clones

* git has bookmarks, that's "normal" git branches

* git has anonymous branches, it's called "detached head" and is completely broken

* git does not have named branches (that's the branch name being part of the commit's immutable metadata)

I've seen plenty of git users put "[JIRA-1234]" at the beginning of a string of commit messages. That's basically poor-man's mercurial named branches.

Isn't that what a tag int Git is for?

A tag applies to an individual commit, and is unique (i.e. you can't have the same tag on multiple commits); a named branch is applied to all commits in a branch and persists after merging. In the example mentioned by @krupan, the users tend to (and some team even require it) prefix each commit with the ticket name or similar identifier.

> the branch name being part of the commit's immutable metadata

To a git user, what's the rationale and when is this useful?

When you want to know were some commit came from.

For example you can make a seemingly unrelated change in a feature branch.

And then later wonder why this change has been done. Of course you could hope to find the merge into master where the feature name could be mentioned. But it’s nicer to have it on the commit.

=> it gives extra context to the commit

Well, considering one is broken I would still argue that it has two, just as the article states. Not that it needs much more -- git branching works perfectly fine.

That said, I'm somewhat disappointed that cloning has fallen out of favour and it's standard to use an upstream server (usually GitHub) not only as a central authority but also as intermediary for sharing code. Apart from "forking", cloning repos has practically been delegated to history.


Perhaps you're thinking of a different meaning of "branch"?

I must be thinking of a different SVN.

You must be thinking of a different TLA.

I am not having a good brain day today :P

They have had branches, at least since I started using hg (2010). But no one uses them. Everyone uses bookmarks as branches.

One of the reasons git is "hard" is because too many people read crap like this, which rapidly gets outdated and often contains more bad advice than good. Read the manual! It's not dry at all, and you'll learn a lot. Pick a random git command and read its man page right now.


Read the git book, too. It's free and serves as a good introduction and helps you learn which man pages you need to consult and when. You don't need to read the whole thing, but the first 3 chapters are indispensible.


Can you give some examples of how git has rapidly changed?

A simpler guide, perhaps, made by an incredibly talented former co-worker of mine: https://ohshitgit.com/

This looks great, thanks!

Reminds me of the git man page generator joke site. https://git-man-page-generator.lokaltog.net/

This only briefly touches on revert commits, and instead shows a lot of (in my opinion) dangerous history-destroying commands.

Why aren't reverts more widely used? It seems a lot of devs I've worked with don't understand them, and to me they seem so simple and are so much safer than destroying/rewriting history.

I will explain a common problem with revert commits:

1. Developer writes some code in a branch.

2. Developer merges code into master before the code was actually ready to be deployed.

3. Developer reverts the merge commit in master to roll back everything.

4. Developer fixes the code in their branch.

5. Developer merges their code into master.

6. Their code doesn't show up in master, since it was already merged in and the revert is part of the official history of the branch in master.

7. Developer has to make a revert of the revert and then untangle the mess.

I can understand that, but I still would prefer that over the alternative of changing history, losing context at why the revert happened (or that it happened at all!), and having to dig through reflog and hope that the machine that it was done on is available and hasn't dumped the code to be able to recover the commit needed.

In your scenario, it's a puzzle to unfuck, but it's unfuckable after a bit of work. In the alternative you run the risk of losing work, or blowing out other's commits and causing work for multiple other team members.

I guess my point was that I feel "revert commits" should be treated as the default, and the goto in most situations, and only using something like `git reset HEAD^ --hard` when you really need to, or a revert won't do. I'll be honest, I sometimes use a "reset and force push" when I've fucked up an ugly merge, or I want to undo the last few commits at once, but it's the exception, not the first tool I reach for.

TIL there are revert commits, which prompted me to actually read the article and not just the HN comments. Thank you!

It's one of my favorite things in git! Don't "pretend the commit didn't happen", actually "undo" the commit (as in commit the reverse of your change).

Not only does it preserve the change in an easy-to-see manner, but you can also provide more context on why you undid your commit (my revert messages often read like "Revert "previous commit message here" due to it potentially causing some older android devices to break. More info at ticket #1234")

Now not only do you have a clear history of what happened (someone added X, then you undid X at a later date), but you also have context for why the change was undone, and can either revert the revert if you need to, or just re-do the work in a new commit later.

It's a great "oh shit" button that I'm much more willing to use since I know I won't have to worry about "rescuing" the commit later. If something goes wrong and I have a hunch it was caused in a commit, i'll often just revert it and investigate later when I have time.

That, and since you're preserving commit history, you can later re-enable that change by making a second revert commit of the first revert.

They don't destroy history, they just move the branch to something that's not a descendant of what it once was. You can get the history back if you want.

See "All the things your branch has ever been" http://h2.jaguarpaw.co.uk/posts/git-survival-guide/

Reflog is analogous to the recycle bin (when used like this). It's nice in a pinch, but I don't want to rely on it, and it doesn't keep information forever.

a revert keeps that history forever in your repo (unless you do something to explicitly delete it), which IMO is just as important as all other commits.

It's great to be able to go get the original commit when the time comes to try the (possibly modified) change again.

This is interesting - I like looking at corner cases of a tool to understand it better.

For people having difficulty with git, I recommend going through the official book [0] on a couple of topics with a toy repo and play with the tool a little bit. Another alternative is to find a simple workflow, and stick with it until you have time to explore git more.

Compared to other tools I've had to use in the past (AccuRev ughh), git is fantastic. Just being able to see what files have been modified without waiting for 10min+ or needing to be connected to a server changes your workflow, but we've probably become accustomed to those benefits, but still notice the arguably crusty command line.

[0] https://git-scm.com/book/en/v2

FWIW here is a previous discussion from 4 years ago: https://news.ycombinator.com/item?id=8102624 (29 comments)

Any suggestions for quickly doing the following: When I clone a former repo on GitHub, I want to also add the original repo I formed from, as the upstream remote. This way I have the original repo which is mine and the upstream repo which is the original. So far I've been doing this manually.

go to https://github.com/github/hub install hub and run: hub fork user/repo

Seeking advice from the git masters :

I joined a new small team several weeks ago. All of us are fairly new to git, coming from cvs and svn backgrounds. We use Intellij as our primary IDE, and bitbucket as our remote origin.

Do y’all recommend using the IntelliJ git front end GUI, or calling git from the command line?

I thought I had a grasp of git from some side projects on GitHub, but now that it’s a key dev tool in our daily process, the more I learn about it and need to extend beyond simple checkout/commit/push workflow, the deeper the rabbit hole goes.

Learn the git cmd prompt first.

Use a text editor eg. Code to fix merges.

Git is powerful. And can have a hard learning curve, but don't have to. Learn it in CMD.

I mostly use

status push pull commit -a add checkout checkout -b branch list merge

Gitk and git GUI usually comes with most installations and works for Mac Windows Linux. Then any other UI is just sugar.

IntelliJ is missing tooling for staging which I am missing. Imho the Eclipse tooling (EGit) is much better in that regard. I never had trouble mixing Eclipse and command line workflows whereas IntelliJ forces me more often to resort to the command line.

As the sibling said, learning the command line first (and the model of Git) is mandatory, especially if you come from a CVS and SVN background. I came from Perforce and had a pretty hard time with Git until I invested two days with a good tutorial and much experimenting with two local and one remote repository.

EDIT: spelling

IMO, by blindly follow these kind of cheatsheet, you will hard to get better with Git.

I used to remember command in certain situation and have a hard time understanding stuff like stash, rebase, cherry-pick, detach head etc...So whenever come up I have to sit google the heck out of it.

Then one day I decide to sit down and just read Git properly. They are on: https://git-scm.com/

Eventually I understand it better and now I know what I need to do in certain situation.

I also highly recommend Learn Git The Hard Way. Most developers who spend an afternoon with it will come away with a firm understanding of git's core abstractions.

Book: https://leanpub.com/learngitthehardway

I was surprised there is no mention of git bisect... an incredibly useful tool.

Isn't the first rule, never talk about Flight rules?

If git confuses

Read chapter 10 of pro git

Mourn enlightenment

that remember this so much https://xkcd.com/1597/

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