user-manual: the name of the hash function is SHA-1, not sha1

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Felipe Contreras 2009-04-04 12:38:27 +03:00 committed by Junio C Hamano
parent a3df1e464e
commit a6e5ef7d9c

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@ -188,7 +188,7 @@ As you can see, a commit shows who made the latest change, what they
did, and why.
Every commit has a 40-hexdigit id, sometimes called the "object name" or the
"SHA1 id", shown on the first line of the "git show" output. You can usually
"SHA-1 id", shown on the first line of the "git show" output. You can usually
refer to a commit by a shorter name, such as a tag or a branch name, but this
longer name can also be useful. Most importantly, it is a globally unique
name for this commit: so if you tell somebody else the object name (for
@ -320,7 +320,7 @@ If you want to create a new branch from this checkout, you may do so
HEAD is now at 427abfa... Linux v2.6.17
------------------------------------------------
The HEAD then refers to the SHA1 of the commit instead of to a branch,
The HEAD then refers to the SHA-1 of the commit instead of to a branch,
and git branch shows that you are no longer on a branch:
------------------------------------------------
@ -739,7 +739,7 @@ $ git log --pretty=oneline origin..mybranch | wc -l
-------------------------------------------------
Alternatively, you may often see this sort of thing done with the
lower-level command linkgit:git-rev-list[1], which just lists the SHA1's
lower-level command linkgit:git-rev-list[1], which just lists the SHA-1's
of all the given commits:
-------------------------------------------------
@ -2865,8 +2865,8 @@ The Object Database
We already saw in <<understanding-commits>> that all commits are stored
under a 40-digit "object name". In fact, all the information needed to
represent the history of a project is stored in objects with such names.
In each case the name is calculated by taking the SHA1 hash of the
contents of the object. The SHA1 hash is a cryptographic hash function.
In each case the name is calculated by taking the SHA-1 hash of the
contents of the object. The SHA-1 hash is a cryptographic hash function.
What that means to us is that it is impossible to find two different
objects with the same name. This has a number of advantages; among
others:
@ -2877,10 +2877,10 @@ others:
same content stored in two repositories will always be stored under
the same name.
- Git can detect errors when it reads an object, by checking that the
object's name is still the SHA1 hash of its contents.
object's name is still the SHA-1 hash of its contents.
(See <<object-details>> for the details of the object formatting and
SHA1 calculation.)
SHA-1 calculation.)
There are four different types of objects: "blob", "tree", "commit", and
"tag".
@ -2926,9 +2926,9 @@ committer Junio C Hamano <gitster@pobox.com> 1187591163 -0700
As you can see, a commit is defined by:
- a tree: The SHA1 name of a tree object (as defined below), representing
- a tree: The SHA-1 name of a tree object (as defined below), representing
the contents of a directory at a certain point in time.
- parent(s): The SHA1 name of some number of commits which represent the
- parent(s): The SHA-1 name of some number of commits which represent the
immediately previous step(s) in the history of the project. The
example above has one parent; merge commits may have more than
one. A commit with no parents is called a "root" commit, and
@ -2977,13 +2977,13 @@ $ git ls-tree fb3a8bdd0ce
------------------------------------------------
As you can see, a tree object contains a list of entries, each with a
mode, object type, SHA1 name, and name, sorted by name. It represents
mode, object type, SHA-1 name, and name, sorted by name. It represents
the contents of a single directory tree.
The object type may be a blob, representing the contents of a file, or
another tree, representing the contents of a subdirectory. Since trees
and blobs, like all other objects, are named by the SHA1 hash of their
contents, two trees have the same SHA1 name if and only if their
and blobs, like all other objects, are named by the SHA-1 hash of their
contents, two trees have the same SHA-1 name if and only if their
contents (including, recursively, the contents of all subdirectories)
are identical. This allows git to quickly determine the differences
between two related tree objects, since it can ignore any entries with
@ -3029,15 +3029,15 @@ currently checked out.
Trust
~~~~~
If you receive the SHA1 name of a blob from one source, and its contents
If you receive the SHA-1 name of a blob from one source, and its contents
from another (possibly untrusted) source, you can still trust that those
contents are correct as long as the SHA1 name agrees. This is because
the SHA1 is designed so that it is infeasible to find different contents
contents are correct as long as the SHA-1 name agrees. This is because
the SHA-1 is designed so that it is infeasible to find different contents
that produce the same hash.
Similarly, you need only trust the SHA1 name of a top-level tree object
Similarly, you need only trust the SHA-1 name of a top-level tree object
to trust the contents of the entire directory that it refers to, and if
you receive the SHA1 name of a commit from a trusted source, then you
you receive the SHA-1 name of a commit from a trusted source, then you
can easily verify the entire history of commits reachable through
parents of that commit, and all of those contents of the trees referred
to by those commits.
@ -3049,7 +3049,7 @@ that you trust that commit, and the immutability of the history of
commits tells others that they can trust the whole history.
In other words, you can easily validate a whole archive by just
sending out a single email that tells the people the name (SHA1 hash)
sending out a single email that tells the people the name (SHA-1 hash)
of the top commit, and digitally sign that email using something
like GPG/PGP.
@ -3090,7 +3090,7 @@ How git stores objects efficiently: pack files
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Newly created objects are initially created in a file named after the
object's SHA1 hash (stored in .git/objects).
object's SHA-1 hash (stored in .git/objects).
Unfortunately this system becomes inefficient once a project has a
lot of objects. Try this on an old project:
@ -3297,7 +3297,7 @@ $ git hash-object -w somedirectory/myfile
------------------------------------------------
which will create and store a blob object with the contents of
somedirectory/myfile, and output the sha1 of that object. if you're
somedirectory/myfile, and output the SHA-1 of that object. if you're
extremely lucky it might be 4b9458b3786228369c63936db65827de3cc06200, in
which case you've guessed right, and the corruption is fixed!
@ -3359,7 +3359,7 @@ The index
-----------
The index is a binary file (generally kept in .git/index) containing a
sorted list of path names, each with permissions and the SHA1 of a blob
sorted list of path names, each with permissions and the SHA-1 of a blob
object; linkgit:git-ls-files[1] can show you the contents of the index:
-------------------------------------------------
@ -3754,7 +3754,7 @@ unsaved state that you might want to restore later!) your current
index. Normal operation is just
-------------------------------------------------
$ git read-tree <sha1 of tree>
$ git read-tree <SHA-1 of tree>
-------------------------------------------------
and your index file will now be equivalent to the tree that you saved
@ -3978,7 +3978,7 @@ $ git ls-files --unmerged
------------------------------------------------
Each line of the `git ls-files --unmerged` output begins with
the blob mode bits, blob SHA1, 'stage number', and the
the blob mode bits, blob SHA-1, 'stage number', and the
filename. The 'stage number' is git's way to say which tree it
came from: stage 1 corresponds to `$orig` tree, stage 2 `HEAD`
tree, and stage3 `$target` tree.
@ -4045,12 +4045,12 @@ objects). There are currently four different object types: "blob",
Regardless of object type, all objects share the following
characteristics: they are all deflated with zlib, and have a header
that not only specifies their type, but also provides size information
about the data in the object. It's worth noting that the SHA1 hash
about the data in the object. It's worth noting that the SHA-1 hash
that is used to name the object is the hash of the original data
plus this header, so `sha1sum` 'file' does not match the object name
for 'file'.
(Historical note: in the dawn of the age of git the hash
was the sha1 of the 'compressed' object.)
was the SHA-1 of the 'compressed' object.)
As a result, the general consistency of an object can always be tested
independently of the contents or the type of the object: all objects can