Create a new manpage for the gitignore format, and reference it elsewhere

Only git-ls-files(1) describes the gitignore format in detail, and it does so
with reference to git-ls-files options.  Most users don't use the plumbing
command git-ls-files directly, and shouldn't have to look in its manpage for
information on the gitignore format.

Create a new manpage gitignore(5) (Documentation/gitignore.txt), and factor
out the gitignore documentation into that file, changing it to refer to
.gitignore and $GIT_DIR/info/exclude as used by porcelain commands.  Reference
gitignore(5) from other relevant manpages and documentation.  Remove
now-redundant information on exclude patterns from git-ls-files(1), leaving
only information on how git-ls-files options specify exclude patterns and what
precedence they have.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

8 files changed, 145 insertions, 101 deletions

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 4064b38..9cef480 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -2,7 +2,7 @@ MAN1_TXT= \
 	$(filter-out $(addsuffix .txt, $(ARTICLES) $(SP_ARTICLES)), \
 		$(wildcard git-*.txt)) \
 	gitk.txt
-MAN5_TXT=gitattributes.txt
+MAN5_TXT=gitattributes.txt gitignore.txt
 MAN7_TXT=git.txt
 
 DOC_HTML=$(patsubst %.txt,%.html,$(MAN1_TXT) $(MAN5_TXT) $(MAN7_TXT))
diff --git a/Documentation/config.txt b/Documentation/config.txt
index fdb71de..7d9afe2 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -266,7 +266,8 @@ Common unit suffixes of 'k', 'm', or 'g' are supported.
 core.excludeFile::
 	In addition to '.gitignore' (per-directory) and
 	'.git/info/exclude', git looks into this file for patterns
-	of files which are not meant to be tracked.
+	of files which are not meant to be tracked.  See
+	gitlink:gitignore[5].
 
 alias.*::
 	Command aliases for the gitlink:git[1] command wrapper - e.g.
diff --git a/Documentation/git-ls-files.txt b/Documentation/git-ls-files.txt
index 43e0d22..a78a9ff 100644
--- a/Documentation/git-ls-files.txt
+++ b/Documentation/git-ls-files.txt
@@ -139,46 +139,24 @@ Exclude Patterns
 
 'git-ls-files' can use a list of "exclude patterns" when
 traversing the directory tree and finding files to show when the
-flags --others or --ignored are specified.
+flags --others or --ignored are specified.  gitlink:gitignore[5]
+specifies the format of exclude patterns.
 
-These exclude patterns come from these places:
+These exclude patterns come from these places, in order:
 
-  1. command line flag --exclude=<pattern> specifies a single
-     pattern.
+  1. The command line flag --exclude=<pattern> specifies a
+     single pattern.  Patterns are ordered in the same order
+     they appear in the command line.
 
-  2. command line flag --exclude-from=<file> specifies a list of
-     patterns stored in a file.
+  2. The command line flag --exclude-from=<file> specifies a
+     file containing a list of patterns.  Patterns are ordered
+     in the same order they appear in the file.
 
   3. command line flag --exclude-per-directory=<name> specifies
      a name of the file in each directory 'git-ls-files'
-     examines, and if exists, its contents are used as an
-     additional list of patterns.
-
-An exclude pattern file used by (2) and (3) contains one pattern
-per line.  A line that starts with a '#' can be used as comment
-for readability.
-
-There are three lists of patterns that are in effect at a given
-time.  They are built and ordered in the following way:
-
- * --exclude=<pattern> from the command line; patterns are
-   ordered in the same order as they appear on the command line.
-
- * lines read from --exclude-from=<file>; patterns are ordered
-   in the same order as they appear in the file.
-
- * When --exclude-per-directory=<name> is specified, upon
-   entering a directory that has such a file, its contents are
-   appended at the end of the current "list of patterns".  They
-   are popped off when leaving the directory.
-
-Each pattern in the pattern list specifies "a match pattern" and
-optionally the fate; either a file that matches the pattern is
-considered excluded or included.  A filename is matched against
-the patterns in the three lists; the --exclude-from list is
-checked first, then the --exclude-per-directory list, and then
-finally the --exclude list. The last match determines its fate.
-If there is no match in the three lists, the fate is "included".
+     examines, normally `.gitignore`.  Files in deeper
+     directories take precedence.  Patterns are ordered in the
+     same order they appear in the files.
 
 A pattern specified on the command line with --exclude or read
 from the file specified with --exclude-from is relative to the
@@ -186,58 +164,9 @@ top of the directory tree.  A pattern read from a file specified
 by --exclude-per-directory is relative to the directory that the
 pattern file appears in.
 
-An exclude pattern is of the following format:
-
- - an optional prefix '!' which means that the fate this pattern
-   specifies is "include", not the usual "exclude"; the
-   remainder of the pattern string is interpreted according to
-   the following rules.
-
- - if it does not contain a slash '/', it is a shell glob
-   pattern and used to match against the filename without
-   leading directories.
-
- - otherwise, it is a shell glob pattern, suitable for
-   consumption by fnmatch(3) with FNM_PATHNAME flag.  I.e. a
-   slash in the pattern must match a slash in the pathname.
-   "Documentation/\*.html" matches "Documentation/git.html" but
-   not "ppc/ppc.html".  As a natural exception, "/*.c" matches
-   "cat-file.c" but not "mozilla-sha1/sha1.c".
-
-An example:
-
---------------------------------------------------------------
-    $ cat .git/info/exclude
-    # ignore objects and archives, anywhere in the tree.
-    *.[oa]
-    $ cat Documentation/.gitignore
-    # ignore generated html files,
-    *.html
-    # except foo.html which is maintained by hand
-    !foo.html
-    $ git-ls-files --ignored \
-        --exclude='Documentation/*.[0-9]' \
-        --exclude-from=.git/info/exclude \
-        --exclude-per-directory=.gitignore
---------------------------------------------------------------
-
-Another example:
-
---------------------------------------------------------------
-    $ cat .gitignore
-    vmlinux*
-    $ ls arch/foo/kernel/vm*
-    arch/foo/kernel/vmlinux.lds.S
-    $ echo '!/vmlinux*' >arch/foo/kernel/.gitignore
---------------------------------------------------------------
-
-The second .gitignore keeps `arch/foo/kernel/vmlinux.lds.S` file
-from getting ignored.
-
-
 See Also
 --------
-gitlink:git-read-tree[1]
+gitlink:git-read-tree[1], gitlink:gitignore[5]
 
 
 Author
@@ -246,7 +175,7 @@ Written by Linus Torvalds <torvalds@osdl.org>
 
 Documentation
 --------------
-Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
+Documentation by David Greaves, Junio C Hamano, Josh Triplett, and the git-list <git@vger.kernel.org>.
 
 GIT
 ---
diff --git a/Documentation/git-read-tree.txt b/Documentation/git-read-tree.txt
index 019c8be..acb5744 100644
--- a/Documentation/git-read-tree.txt
+++ b/Documentation/git-read-tree.txt
@@ -341,7 +341,8 @@ have finished your work-in-progress), attempt the merge again.
 
 See Also
 --------
-gitlink:git-write-tree[1]; gitlink:git-ls-files[1]
+gitlink:git-write-tree[1]; gitlink:git-ls-files[1];
+gitlink:gitignore[5]
 
 
 Author
diff --git a/Documentation/git-status.txt b/Documentation/git-status.txt
index d701538..1fd1af1 100644
--- a/Documentation/git-status.txt
+++ b/Documentation/git-status.txt
@@ -42,11 +42,9 @@ mean the same thing and the latter is kept for backward
 compatibility) and `color.status.<slot>` configuration variables
 to colorize its output.
 
-As for gitlink:git-add[1], the configuration variable
-'core.excludesfile' can indicate a path to a file containing patterns
-of file names to exclude, in addition to patterns given in
-'info/exclude' and '.gitignore'.
-
+See Also
+--------
+gitlink:gitignore[5]
 
 Author
 ------
diff --git a/Documentation/gitignore.txt b/Documentation/gitignore.txt
new file mode 100644
index 0000000..ea79d74
--- /dev/null
+++ b/Documentation/gitignore.txt
@@ -0,0 +1,116 @@
+gitignore(5)
+============
+
+NAME
+----
+gitignore - Specifies intentionally untracked files to ignore
+
+SYNOPSIS
+--------
+$GIT_DIR/info/exclude, .gitignore
+
+DESCRIPTION
+-----------
+
+A `gitignore` file specifies intentionally untracked files that
+git should ignore.  Each line in a `gitignore` file specifies a
+pattern.
+
+When deciding whether to ignore a path, git normally checks
+`gitignore` patterns from multiple sources, with the following
+order of precedence:
+
+ * Patterns read from the file specified by the configuration
+   variable 'core.excludesfile'.
+
+ * Patterns read from `$GIT_DIR/info/exclude`.
+
+ * Patterns read from a `.gitignore` file in the same directory
+   as the path, or in any parent directory, ordered from the
+   deepest such file to a file in the root of the repository.
+   These patterns match relative to the location of the
+   `.gitignore` file.  A project normally includes such
+   `.gitignore` files in its repository, containing patterns for
+   files generated as part of the project build.
+
+The underlying git plumbing tools, such as
+gitlink:git-ls-files[1] and gitlink:git-read-tree[1], read
+`gitignore` patterns specified by command-line options, or from
+files specified by command-line options.  Higher-level git
+tools, such as gitlink:git-status[1] and gitlink:git-add[1],
+use patterns from the sources specified above.
+
+Patterns have the following format:
+
+ - A blank line matches no files, so it can serve as a separator
+   for readability.
+
+ - A line starting with # serves as a comment.
+
+ - An optional prefix '!' which negates the pattern; any
+   matching file excluded by a previous pattern will become
+   included again.
+
+ - If the pattern does not contain a slash '/', git treats it as
+   a shell glob pattern and checks for a match against the
+   pathname without leading directories.
+
+ - Otherwise, git treats the pattern as a shell glob suitable
+   for consumption by fnmatch(3) with the FNM_PATHNAME flag:
+   wildcards in the pattern will not match a / in the pathname.
+   For example, "Documentation/\*.html" matches
+   "Documentation/git.html" but not
+   "Documentation/ppc/ppc.html".  A leading slash matches the
+   beginning of the pathname; for example, "/*.c" matches
+   "cat-file.c" but not "mozilla-sha1/sha1.c".
+
+An example:
+
+--------------------------------------------------------------
+    $ git-status
+    [...]
+    # Untracked files:
+    [...]
+    #       Documentation/foo.html
+    #       Documentation/gitignore.html
+    #       file.o
+    #       lib.a
+    #       src/internal.o
+    [...]
+    $ cat .git/info/exclude
+    # ignore objects and archives, anywhere in the tree.
+    *.[oa]
+    $ cat Documentation/.gitignore
+    # ignore generated html files,
+    *.html
+    # except foo.html which is maintained by hand
+    !foo.html
+    $ git-status
+    [...]
+    # Untracked files:
+    [...]
+    #       Documentation/foo.html
+    [...]
+--------------------------------------------------------------
+
+Another example:
+
+--------------------------------------------------------------
+    $ cat .gitignore
+    vmlinux*
+    $ ls arch/foo/kernel/vm*
+    arch/foo/kernel/vmlinux.lds.S
+    $ echo '!/vmlinux*' >arch/foo/kernel/.gitignore
+--------------------------------------------------------------
+
+The second .gitignore prevents git from ignoring
+`arch/foo/kernel/vmlinux.lds.S`.
+
+Documentation
+-------------
+Documentation by David Greaves, Junio C Hamano, Josh Triplett,
+Frank Lichtenheld, and the git-list <git@vger.kernel.org>.
+
+GIT
+---
+Part of the gitlink:git[7] suite
diff --git a/Documentation/repository-layout.txt b/Documentation/repository-layout.txt
index 0459bd9..15221b5 100644
--- a/Documentation/repository-layout.txt
+++ b/Documentation/repository-layout.txt
@@ -155,8 +155,7 @@ info/exclude::
 	exclude pattern list. `.gitignore` is the per-directory
 	ignore file.  `git status`, `git add`, `git rm` and `git
 	clean` look at it but the core git commands do not look
-	at it.  See also: gitlink:git-ls-files[1] `--exclude-from`
-	and `--exclude-per-directory`.
+	at it.  See also: gitlink:gitignore[5].
 
 remotes::
 	Stores shorthands to be used to give URL and default
diff --git a/Documentation/user-manual.txt b/Documentation/user-manual.txt
index 4fabb8e..7eaafa8 100644
--- a/Documentation/user-manual.txt
+++ b/Documentation/user-manual.txt
@@ -1103,12 +1103,12 @@ 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:
+gitlink:gitignore[5] 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.