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Update tutorial.txt branches/tags to use the nicer helper syntax

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Teach people to use "git tag <tag-name>" instead of writing the current
HEAD by hand into the .git/refs/tags/<tag-name> file.  Most people
probably don't really want to know about how git does things internally.
This commit is contained in:
Linus Torvalds
2005-07-23 15:24:53 -07:00
parent d727782eaf
commit a7333f9e56
1 changed files with 31 additions and 21 deletions
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52
Documentation/tutorial.txt
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@ -472,10 +472,11 @@ A "light" tag is technically nothing more than a branch, except we put
it in the ".git/refs/tags/" subdirectory instead of calling it a "head". it in the ".git/refs/tags/" subdirectory instead of calling it a "head".
So the simplest form of tag involves nothing more than So the simplest form of tag involves nothing more than
cat .git/HEAD > .git/refs/tags/my-first-tag git tag my-first-tag
after which point you can use this symbolic name for that particular which just writes the current HEAD into the .git/refs/tags/my-first-tag
state. You can, for example, do file, after which point you can then use this symbolic name for that
particular state. You can, for example, do
git diff my-first-tag git diff my-first-tag
@ -487,9 +488,9 @@ since you tagged it.
A "signed tag" is actually a real git object, and contains not only a A "signed tag" is actually a real git object, and contains not only a
pointer to the state you want to tag, but also a small tag name and pointer to the state you want to tag, but also a small tag name and
message, along with a PGP signature that says that yes, you really did message, along with a PGP signature that says that yes, you really did
that tag. You create these signed tags with that tag. You create these signed tags with the "-s" flag to "git tag":
git tag <tagname> git tag -s <tagname>
which will sign the current HEAD (but you can also give it another which will sign the current HEAD (but you can also give it another
argument that specifies the thing to tag, ie you could have tagged the argument that specifies the thing to tag, ie you could have tagged the
@ -620,7 +621,7 @@ repository, and checked it out.
--------------------- ---------------------
Branches in git are really nothing more than pointers into the git Branches in git are really nothing more than pointers into the git
object space from within the ",git/refs/" subdirectory, and as we object space from within the ".git/refs/" subdirectory, and as we
already discussed, the HEAD branch is nothing but a symlink to one of already discussed, the HEAD branch is nothing but a symlink to one of
these object pointers. these object pointers.
@ -632,36 +633,45 @@ want (and indeed, subdirectories), but the convention is that the
and nothing enforces it. and nothing enforces it.
To show that as an example, let's go back to the git-tutorial archive we To show that as an example, let's go back to the git-tutorial archive we
used earlier, and create a branch in it. You literally do that by just used earlier, and create a branch in it. You do that by simply just
creating a new SHA1 reference file, and switch to it by just making the saying that you want to check out a new branch:
HEAD pointer point to it:
cat .git/HEAD > .git/refs/heads/mybranch git checkout -b mybranch
ln -sf refs/heads/mybranch .git/HEAD
and you're done. will create a new branch based at the current HEAD position, and switch
to it.
Now, if you make the decision to start your new branch at some other [ Side note: if you make the decision to start your new branch at some
point in the history than the current HEAD, you usually also want to other point in the history than the current HEAD, you can do so by
actually switch the contents of your working directory to that point just telling "git checkout" what the base of the checkout would be.
when you switch the head, and "git checkout" will do that for you: In other words, if you have an earlier tag or branch, you'd just do
instead of switching the branch by hand with "ln -sf", you can just do
git checkout mybranch git checkout -b mybranch earlier-branch
which will basically "jump" to the branch specified, update your working and it would create the new branch "mybranch" at the earlier point,
directory to that state, and also make it become the new default HEAD. and check out the state at that time. ]
You can always just jump back to your original "master" branch by doing You can always just jump back to your original "master" branch by doing
git checkout master git checkout master
and if you forget which branch you happen to be on, a simple (or any other branch-name, for that matter) and if you forget which
branch you happen to be on, a simple
ls -l .git/HEAD ls -l .git/HEAD
will tell you where it's pointing. will tell you where it's pointing.
NOTE! Sometimes you may wish to create a new branch _without_ actually
checking it out and switching to it. If so, just use the command
git branch <branchname> [startingpoint]
which will simply _create_ the branch, but will not do anything further.
You can then later - once you decide that you want to actually develop
on that branch - switch to that branch with a regular "git checkout"
with the branchname as the argument.
Merging two branches Merging two branches
-------------------- --------------------