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Fossil: Hints For Users With Prior Git Experience

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Hints For Users With Prior Git Experience
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This document is a semi-random collection of hints intended to help new users of Fossil who have had prior exposure to Git. In other words, this document tries to describe the differences in how Fossil works from the perspective of Git users.

Help Improve This Document

If you have a lot of prior Git experience, and you are new to Fossil and are struggling with some concepts, please ask for help on the Fossil Forum. The people who write this document are intimately familiar with Fossil and less familiar with Git. It is difficult for us to anticipate the perspective of people who are initimately familiar with Git and less familiar with Fossil. Asking questions on the Forum will help us to improve the document.

Specific suggestions on how to improve this document are also welcomed, of course.

Repositories And Checkouts Are Distinct

A repository and a check-out are distinct concepts in Fossil, whereas the two are often conflated with Git. A repository is a database in which the entire history of a project is stored. A check-out is a directory hierarchy that contains a snapshot of your project that you are currently working on. See detailed definitions for more information. With Git, the repository and check-out are closely related - the repository is the contents of the ".git" subdirectory at the root of your check-out. But with Fossil, the repository and the check-out are completely separate. A Fossil repository can reside in the same directory hierarchy with the check-out as with Git, but it is more common to put the repository in a separate directory.

Fossil repositories are a single file, rather than being a directory hierarchy as with the ".git" folder in Git. The repository file can be named anything you want, but it is best to use the ".fossil" suffix. Many people choose to gather all of their Fossil repositories in a single directory on their machine, such as "~/Fossils" or "C:\Fossils". This can help humans to keep their repositories organized, but Fossil itself doesn't really care.

Because Fossil cleanly separates the repository from the check-out, it is routine to have multiple check-outs from the same repository. Each check-out can be on a separate branch, or on the same branch. Each check-out operates independently of the others.

Each Fossil check-out contains a file (usually named ".fslckout" on unix or "_FOSSIL_" on Windows) that keeps track of the status of that particular check-out and keeps a pointer to the repository. If you move or rename the repository file, the check-outs won't be able to find it and will complain. But you can freely move check-outs around without causing any problems.

There Is No Staging Area

Fossil omits the "Git index" or "staging area" concept. When you type "fossil commit" all changes in your check-out are committed, automatically. There is no need for the "-a" option as with Git.

If you only want to commit just some of the changes, you can list the names of the files you want to commit as arguments, like this:

    fossil commit src/main.c doc/readme.md

Create Branches After-The-Fact

Fossil perfers that you create new branches when you commit using the "--branch BRANCH-NAME" command-line option. For example:

    fossil commit --branch my-new-branch

It is not necessary to create branches ahead of time, as in Git, though that is allowed using the "fossil branch new" command, if you prefer. Fossil also allows you to move a check-in to a different branch after you commit it, using the "fossil amend" command. For example:

    fossil amend current --branch my-new-branch

Autosync

Fossil has a feature called "autosync". Autosync defaults on. When autosync is enabled, Fossil automatically pushes your changes to the remote server whenever you "fossil commit". It also automatically pulls all remote changes down to your local repository before you "fossil update".

Autosync provides most of the advantages of a centralized version control system while retaining the advantages of distributed version control. Your work stays synced up with your coworkers at all times. If your local machine dies catastrophically, you haven't lost any (committed) work. But you can still work and commit while off network, with changes resyncing automatically when you get back on-line.

Syncing Is All-Or-Nothing

Fossil does not support the concept of syncing, pushing, or pulling individual branches. When you sync/push/pull in Fossil, you sync/push/pull everything - all branches, all wiki, all tickets, all forum posts, all tags, all technotes - everything.

The Main Branch Is Called "trunk", not "master"

In Fossil, the traditional name and the default name for the main branch is "trunk". The "trunk" branch in Fossil corresponds to the "master" branch in Git.

These naming conventions are so embedded in each system, that the "trunk" branch name is automatically translated to "master" when a Fossil repo is mirrored to GitHub.

The "fossil status" Command Does Not Show Unmanaged Files

The "fossil status" command shows you what files in your check-out have been edited and scheduled for adding or removing at the next commit. But unlike "git status", the "fossil status" command does not warn you about unmanaged files in your local check-out. There is a separate "fossil extras" command for that.

There Is No Rebase

Fossil does not support rebase. This is a deliberate design decision that has been thoroughly, carefully, and throughtfully discussed, many times. If you are fond of rebase, you should read the Rebase Considered Harmful document carefully before expressing your views.

Branch and Tag Names

Fossil has no special restrictions on the names of tags and branches, though you might want to to keep Git's tag and branch name restrictions in mind if you plan on mirroring your Fossil repository to GitHub.

Fossil does not require tag and branch names to be unique. It is common, for example, to put a "release" tag on every release for a Fossil-hosted project.

Only One "origin" At A Time

A Fossil repository only keeps track of one "origin" server at a time. If you specify a new "origin" it forgets the previous one. Use the "fossil remote" command to see or change the "origin".

Fossil uses a very different sync protocol than Git, so it isn't as important for Fossil to keep track of multiple origins as it is with Git. So only having a single origin has never been a big enough problem in Fossil that somebody felt the need to extend it.

Maybe we will add multiple origin support to Fossil someday. Patches are welcomed if you want to have a go at it.

Cherry-pick Is An Option To The "merge" Command

In Git, "git cherry-pick" is a separate command. In Fossil, "fossil merge --cherrypick" is an option on the merge command. Otherwise, they work mostly the same.

Except, the Fossil file format remembers cherrypicks and actually shows them as dashed lines on the graphical DAG display, whereas there is no provision for recording cherry-picks in the Git file format, so you have to talk about the cherry-pick in the commit comment if you want to remember it.

The "fossil mv" and "fossil rm" Commands Do Not Actually Rename Or Delete The Files (by default)

By default, the "fossil mv" and "fossil rm" commands work like they do in CVS in that they schedule the changes for the next commit, but do not actually rename or delete the files in your check-out. You can to add the "--hard" option to also changes the files in your check-out. If you run

     fossil setting --global mv-rm-files 1

it makes a notation in your per-user "~/.fossil" settings file so that the "--hard" behavior becomes the new default.