3. Introducing Mercurial#

3.1. Introduction#

Mercurial manages a distributed repository containing revisions trees (each revision indicates the changes required to obtain the next, and so on). Locally, we have a repository containing revisions tree, and a working directory. It is possible to put in its working directory, one of the versions of its local repository, modify and then push it in its repository. It is also possible to get revisions from another repository or to export its own revisions from the local repository to another repository.

In contrast to CVS/Subversion, we usually create a repository per project to manage.

In a collaborative development, we usually create a central repository accessible to all developers of the project. These central repository is used as a reference. According to their needs, everyone can have a local repository, that they will have to synchronize with the central repository from time to time.

3.2. Major commands#

  • Create a local repository:

    hg clone ssh://myhost//home/src/repo
  • See the contents of the local repository (graphical tool in Qt):

  • Add a sub-directory or file in the current directory:

    hg add subdir
  • Move to the working directory a specific revision (or last revision) from the local repository:

    hg update [identifier-revision]
    hg up [identifier-revision]
  • Get in its local repository, the tree of revisions contained in a remote repository (this does not change the local directory):

    hg pull ssh://myhost//home/src/repo
    hg pull -u ssh://myhost//home/src/repo # equivalent to pull + update
  • See what are the heads of branches of the local repository if a pull returned a new branch:

    hg heads
  • Submit the working directory in the local repository (and create a new revision):

    hg commit
    hg ci
  • Merge with the mother revision of local directory, another revision from the local respository (the new revision will be then two mothers revisions):

    hg merge identifier-revision
  • Export to a remote repository, the tree of revisions in its content local respository (this does not change the local directory):

    hg push ssh://myhost//home/src/repo
  • See what local revisions are not in another repository:

    hg outgoing ssh://myhost//home/src/repo
  • See what are the revisions of a repository not found locally:

    hg incoming ssh://myhost//home/src/repo
  • See what is the revision of the local repository which has been taken out from the working directory and amended:

    hg parent
  • See the differences between the working directory and the mother revision of the local repository, possibly to submit them in the local repository:

    hg diff
    hg commit-tool
    hg ct

3.3. Best Practices#

  • Remember to hg pull -u regularly, and particularly before

    a hg commit.

  • Remember to hg push when your repository contains a version relatively stable of your changes.

  • If a hg pull -u created a new branch head:

    1. find its identifier with hg head

    2. merge with hg merge

    3. hg ci

    4. hg push

3.4. More information#

For more information about Mercurial, please refer to the Mercurial project online documentation.