Merge branch 'maint' of git://linux-nfs.org/~bfields/git into maint

* 'maint' of git://linux-nfs.org/~bfields/git:
  user-manual: Add section on ignoring files
  user-manual: finding commits referencing given file content
  user-manual: discourage shared repository
  tutorial: revise index introduction
  tutorials: add user-manual links

Documentation/tutorial-2.txt

@@ -391,6 +391,9 @@ with the commands mentioned in link:everyday.html[Everyday git].  You
 should be able to find any unknown jargon in the
 link:glossary.html[Glossary].
 
+The link:user-manual.html[Git User's Manual] provides a more
+comprehensive introduction to git.
+
 The link:cvs-migration.html[CVS migration] document explains how to
 import a CVS repository into git, and shows how to use git in a
 CVS-like way.

Documentation/tutorial.txt

@@ -4,6 +4,10 @@ A tutorial introduction to git (for version 1.5.1 or newer)
 This tutorial explains how to import a new project into git, make
 changes to it, and share changes with other developers.
 
+If you are instead primarily interested in using git to fetch a project,
+for example, to test the latest version, you may prefer to start with
+the first two chapters of link:user-manual.html[The Git User's Manual].
+
 First, note that you can get documentation for a command such as "git
 diff" with:
 
@@ -40,50 +44,76 @@ Initialized empty Git repository in .git/
 ------------------------------------------------
 
 You've now initialized the working directory--you may notice a new
-directory created, named ".git".  Tell git that you want it to track
-every file under the current directory (note the '.') with:
+directory created, named ".git".
+
+Next, tell git to take a snapshot of the contents of all files under the
+current directory (note the '.'), with gitlink:git-add[1]:
 
 ------------------------------------------------
 $ git add .
 ------------------------------------------------
 
-Finally,
+This snapshot is now stored in a temporary staging area which git calls
+the "index".  You can permanently store the contents of the index in the
+repository with gitlink:git-commit[1]:
 
 ------------------------------------------------
 $ git commit
 ------------------------------------------------
 
-will prompt you for a commit message, then record the current state
-of all the files to the repository.
+This will prompt you for a commit message.  You've now stored the first
+version of your project in git.
 
 Making changes
 --------------
 
-Try modifying some files, then run
+Modify some files, then add their updated contents to the index:
 
 ------------------------------------------------
-$ git diff
+$ git add file1 file2 file3
 ------------------------------------------------
 
-to review your changes.  When you're done, tell git that you
-want the updated contents of these files in the commit and then
-make a commit, like this:
+You are now ready to commit.  You can see what is about to be committed
+using gitlink:git-diff[1] with the --cached option:
+
+------------------------------------------------
+$ git diff --cached
+------------------------------------------------
+
+(Without --cached, gitlink:git-diff[1] will show you any changes that
+you've made but not yet added to the index.)  You can also get a brief
+summary of the situation with gitlink:git-status[1]:
+
+------------------------------------------------
+$ git status
+# On branch master
+# Changes to be committed:
+#   (use "git reset HEAD <file>..." to unstage)
+#
+#	modified:   file1
+#	modified:   file2
+#	modified:   file3
+#
+------------------------------------------------
+
+If you need to make any further adjustments, do so now, and then add any
+newly modified content to the index.  Finally, commit your changes with:
 
 ------------------------------------------------
-$ git add file1 file2 file3
 $ git commit
 ------------------------------------------------
 
 This will again prompt your for a message describing the change, and then
-record the new versions of the files you listed.
+record a new version of the project.
 
 Alternatively, instead of running `git add` beforehand, you can use
 
 ------------------------------------------------
 $ git commit -a
 ------------------------------------------------
 
-which will automatically notice modified (but not new) files.
+which will automatically notice any modified (but not new) files, add
+them to the index, and commit, all in one step.
 
 A note on commit messages: Though not required, it's a good idea to
 begin the commit message with a single short (less than 50 character)
@@ -92,45 +122,15 @@ thorough description.  Tools that turn commits into email, for
 example, use the first line on the Subject: line and the rest of the
 commit in the body.
 
-
 Git tracks content not files
 ----------------------------
 
-With git you have to explicitly "add" all the changed _content_ you
-want to commit together. This can be done in a few different ways:
-
-1) By using 'git add <file_spec>...'
-
-This can be performed multiple times before a commit.  Note that this
-is not only for adding new files.  Even modified files must be
-added to the set of changes about to be committed.  The "git status"
-command gives you a summary of what is included so far for the
-next commit.  When done you should use the 'git commit' command to
-make it real.
-
-Note: don't forget to 'add' a file again if you modified it after the
-first 'add' and before 'commit'. Otherwise only the previous added
-state of that file will be committed. This is because git tracks
-content, so what you're really 'adding' to the commit is the *content*
-of the file in the state it is in when you 'add' it.
-
-2) By using 'git commit -a' directly
-
-This is a quick way to automatically 'add' the content from all files
-that were modified since the previous commit, and perform the actual
-commit without having to separately 'add' them beforehand.  This will
-not add content from new files i.e. files that were never added before.
-Those files still have to be added explicitly before performing a
-commit.
-
-But here's a twist. If you do 'git commit <file1> <file2> ...' then only
-the  changes belonging to those explicitly specified files will be
-committed, entirely bypassing the current "added" changes. Those "added"
-changes will still remain available for a subsequent commit though.
-
-However, for normal usage you only have to remember 'git add' + 'git commit'
-and/or 'git commit -a'.
-
+Many revision control systems provide an "add" command that tells the
+system to start tracking changes to a new file.  Git's "add" command
+does something simpler and more powerful: `git add` is used both for new
+and newly modified files, and in both cases it takes a snapshot of the
+given files and stages that content in the index, ready for inclusion in
+the next commit.
 
 Viewing the changelog
 ---------------------
@@ -564,7 +564,7 @@ link:tutorial-2.html[Part two of this tutorial] explains the object
 database, the index file, and a few other odds and ends that you'll
 need to make the most of git.
 
-If you don't want to consider with that right away, a few other
+If you don't want to continue with that right away, a few other
 digressions that may be interesting at this point are:
 
   * gitlink:git-format-patch[1], gitlink:git-am[1]: These convert

Documentation/user-manual.txt

@@ -921,6 +921,22 @@ echo "git diff --stat --summary -M v$last v$new > ../diffstat-$new"
 and then he just cut-and-pastes the output commands after verifying that
 they look OK.
 
+Finding commits referencing a file with given content
+-----------------------------------------------------
+
+Somebody hands you a copy of a file, and asks which commits modified a
+file such that it contained the given content either before or after the
+commit.  You can find out with this:
+
+-------------------------------------------------
+$  git log --raw -r --abbrev=40 --pretty=oneline -- filename |
+	grep -B 1 `git hash-object filename`
+-------------------------------------------------
+
+Figuring out why this works is left as an exercise to the (advanced)
+student.  The gitlink:git-log[1], gitlink:git-diff-tree[1], and
+gitlink:git-hash-object[1] man pages may prove helpful.
+
 [[Developing-with-git]]
 Developing with git
 ===================
@@ -1073,6 +1089,75 @@ description.  Tools that turn commits into email, for example, use
 the first line on the Subject line and the rest of the commit in the
 body.
 
+[[ignoring-files]]
+Ignoring files
+--------------
+
+A project will often generate files that you do 'not' want to track with git.
+This typically includes files generated by a build process or temporary
+backup files made by your editor. Of course, 'not' tracking files with git
+is just a matter of 'not' calling "`git add`" on them. But it quickly becomes
+annoying to have these untracked files lying around; e.g. they make
+"`git add .`" and "`git commit -a`" practically useless, and they keep
+showing up in the output of "`git status`", etc.
+
+Git therefore provides "exclude patterns" for telling git which files to
+actively ignore. Exclude patterns are thoroughly explained in the
+"Exclude Patterns" section of the gitlink:git-ls-files[1] manual page,
+but the heart of the concept is simply a list of files which git should
+ignore. Entries in the list may contain globs to specify multiple files,
+or may be prefixed by "`!`" to explicitly include (un-ignore) a previously
+excluded (ignored) file (i.e. later exclude patterns override earlier ones).
+The following example should illustrate such patterns:
+
+-------------------------------------------------
+# Lines starting with '#' are considered comments.
+# Ignore foo.txt.
+foo.txt
+# Ignore (generated) html files,
+*.html
+# except foo.html which is maintained by hand.
+!foo.html
+# Ignore objects and archives.
+*.[oa]
+-------------------------------------------------
+
+The next question is where to put these exclude patterns so that git can
+find them. Git looks for exclude patterns in the following files:
+
+`.gitignore` files in your working tree:::
+	   You may store multiple `.gitignore` files at various locations in your
+	   working tree. Each `.gitignore` file is applied to the directory where
+	   it's located, including its subdirectories. Furthermore, the
+	   `.gitignore` files can be tracked like any other files in your working
+	   tree; just do a "`git add .gitignore`" and commit. `.gitignore` is
+	   therefore the right place to put exclude patterns that are meant to
+	   be shared between all project participants, such as build output files
+	   (e.g. `\*.o`), etc.
+`.git/info/exclude` in your repo:::
+	   Exclude patterns in this file are applied to the working tree as a
+	   whole. Since the file is not located in your working tree, it does
+	   not follow push/pull/clone like `.gitignore` can do. This is therefore
+	   the place to put exclude patterns that are local to your copy of the
+	   repo (i.e. 'not' shared between project participants), such as
+	   temporary backup files made by your editor (e.g. `\*~`), etc.
+The file specified by the `core.excludesfile` config directive:::
+	   By setting the `core.excludesfile` config directive you can tell git
+	   where to find more exclude patterns (see gitlink:git-config[1] for
+	   more information on configuration options). This config directive
+	   can be set in the per-repo `.git/config` file, in which case the
+	   exclude patterns will apply to that repo only. Alternatively, you
+	   can set the directive in the global `~/.gitconfig` file to apply
+	   the exclude pattern to all your git repos. As with the above
+	   `.git/info/exclude` (and, indeed, with git config directives in
+	   general), this directive does not follow push/pull/clone, but remain
+	   local to your repo(s).
+
+[NOTE]
+In addition to the above alternatives, there are git commands that can take
+exclude patterns directly on the command line. See gitlink:git-ls-files[1]
+for an example of this.
+
 [[how-to-merge]]
 How to merge
 ------------
@@ -1857,6 +1942,27 @@ all push to and pull from a single shared repository.  See
 link:cvs-migration.txt[git for CVS users] for instructions on how to
 set this up.
 
+However, while there is nothing wrong with git's support for shared
+repositories, this mode of operation is not generally recommended,
+simply because the mode of collaboration that git supports--by
+exchanging patches and pulling from public repositories--has so many
+advantages over the central shared repository:
+
+	- Git's ability to quickly import and merge patches allows a
+	  single maintainer to process incoming changes even at very
+	  high rates.  And when that becomes too much, git-pull provides
+	  an easy way for that maintainer to delegate this job to other
+	  maintainers while still allowing optional review of incoming
+	  changes.
+	- Since every developer's repository has the same complete copy
+	  of the project history, no repository is special, and it is
+	  trivial for another developer to take over maintenance of a
+	  project, either by mutual agreement, or because a maintainer
+	  becomes unresponsive or difficult to work with.
+	- The lack of a central group of "committers" means there is
+	  less need for formal decisions about who is "in" and who is
+	  "out".
+
 [[setting-up-gitweb]]
 Allowing web browsing of a repository
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -3816,8 +3922,6 @@ Think about how to create a clear chapter dependency graph that will
 allow people to get to important topics without necessarily reading
 everything in between.
 
-Say something about .gitignore.
-
 Scan Documentation/ for other stuff left out; in particular:
 	howto's
 	some of technical/?