Documentation / pull-fetch-param.txton commit documentation: add tutorial for first contribution (76644e3)
   1<repository>::
   2        The "remote" repository that is the source of a fetch
   3        or pull operation.  This parameter can be either a URL
   4        (see the section <<URLS,GIT URLS>> below) or the name
   5        of a remote (see the section <<REMOTES,REMOTES>> below).
   6
   7ifndef::git-pull[]
   8<group>::
   9        A name referring to a list of repositories as the value
  10        of remotes.<group> in the configuration file.
  11        (See linkgit:git-config[1]).
  12endif::git-pull[]
  13
  14<refspec>::
  15        Specifies which refs to fetch and which local refs to update.
  16        When no <refspec>s appear on the command line, the refs to fetch
  17        are read from `remote.<repository>.fetch` variables instead
  18ifndef::git-pull[]
  19        (see <<CRTB,CONFIGURED REMOTE-TRACKING BRANCHES>> below).
  20endif::git-pull[]
  21ifdef::git-pull[]
  22        (see linkgit:git-fetch[1]).
  23endif::git-pull[]
  24+
  25The format of a <refspec> parameter is an optional plus
  26`+`, followed by the source <src>, followed
  27by a colon `:`, followed by the destination ref <dst>.
  28The colon can be omitted when <dst> is empty.  <src> is
  29typically a ref, but it can also be a fully spelled hex object
  30name.
  31+
  32`tag <tag>` means the same as `refs/tags/<tag>:refs/tags/<tag>`;
  33it requests fetching everything up to the given tag.
  34+
  35The remote ref that matches <src>
  36is fetched, and if <dst> is not an empty string, an attempt
  37is made to update the local ref that matches it.
  38+
  39Whether that update is allowed without `--force` depends on the ref
  40namespace it's being fetched to, the type of object being fetched, and
  41whether the update is considered to be a fast-forward. Generally, the
  42same rules apply for fetching as when pushing, see the `<refspec>...`
  43section of linkgit:git-push[1] for what those are. Exceptions to those
  44rules particular to 'git fetch' are noted below.
  45+
  46Until Git version 2.20, and unlike when pushing with
  47linkgit:git-push[1], any updates to `refs/tags/*` would be accepted
  48without `+` in the refspec (or `--force`). When fetching, we promiscuously
  49considered all tag updates from a remote to be forced fetches.  Since
  50Git version 2.20, fetching to update `refs/tags/*` works the same way
  51as when pushing. I.e. any updates will be rejected without `+` in the
  52refspec (or `--force`).
  53+
  54Unlike when pushing with linkgit:git-push[1], any updates outside of
  55`refs/{tags,heads}/*` will be accepted without `+` in the refspec (or
  56`--force`), whether that's swapping e.g. a tree object for a blob, or
  57a commit for another commit that's doesn't have the previous commit as
  58an ancestor etc.
  59+
  60Unlike when pushing with linkgit:git-push[1], there is no
  61configuration which'll amend these rules, and nothing like a
  62`pre-fetch` hook analogous to the `pre-receive` hook.
  63+
  64As with pushing with linkgit:git-push[1], all of the rules described
  65above about what's not allowed as an update can be overridden by
  66adding an the optional leading `+` to a refspec (or using `--force`
  67command line option). The only exception to this is that no amount of
  68forcing will make the `refs/heads/*` namespace accept a non-commit
  69object.
  70+
  71[NOTE]
  72When the remote branch you want to fetch is known to
  73be rewound and rebased regularly, it is expected that
  74its new tip will not be descendant of its previous tip
  75(as stored in your remote-tracking branch the last time
  76you fetched).  You would want
  77to use the `+` sign to indicate non-fast-forward updates
  78will be needed for such branches.  There is no way to
  79determine or declare that a branch will be made available
  80in a repository with this behavior; the pulling user simply
  81must know this is the expected usage pattern for a branch.
  82ifdef::git-pull[]
  83+
  84[NOTE]
  85There is a difference between listing multiple <refspec>
  86directly on 'git pull' command line and having multiple
  87`remote.<repository>.fetch` entries in your configuration
  88for a <repository> and running a
  89'git pull' command without any explicit <refspec> parameters.
  90<refspec>s listed explicitly on the command line are always
  91merged into the current branch after fetching.  In other words,
  92if you list more than one remote ref, 'git pull' will create
  93an Octopus merge.  On the other hand, if you do not list any
  94explicit <refspec> parameter on the command line, 'git pull'
  95will fetch all the <refspec>s it finds in the
  96`remote.<repository>.fetch` configuration and merge
  97only the first <refspec> found into the current branch.
  98This is because making an
  99Octopus from remote refs is rarely done, while keeping track
 100of multiple remote heads in one-go by fetching more than one
 101is often useful.
 102endif::git-pull[]