1 files changed, 102 insertions, 12 deletions
diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index d2a0a76e6c..45577117c2 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -21,30 +21,58 @@ code.  For git in general, three rough rules are:
 
 As for more concrete guidelines, just imitate the existing code
 (this is a good guideline, no matter which project you are
-contributing to).  But if you must have a list of rules,
-here they are.
+contributing to). It is always preferable to match the _local_
+convention. New code added to git suite is expected to match
+the overall style of existing code. Modifications to existing
+code is expected to match the style the surrounding code already
+uses (even if it doesn't match the overall style of existing code).
+
+But if you must have a list of rules, here they are.
 
 For shell scripts specifically (not exhaustive):
 
+ - We use tabs for indentation.
+
+ - Case arms are indented at the same depth as case and esac lines.
+
+ - Redirection operators should be written with space before, but no
+   space after them.  In other words, write 'echo test >"$file"'
+   instead of 'echo test> $file' or 'echo test > $file'.  Note that
+   even though it is not required by POSIX to double-quote the
+   redirection target in a variable (as shown above), our code does so
+   because some versions of bash issue a warning without the quotes.
+
  - We prefer $( ... ) for command substitution; unlike ``, it
    properly nests.  It should have been the way Bourne spelled
    it from day one, but unfortunately isn't.
 
- - We use ${parameter-word} and its [-=?+] siblings, and their
-   colon'ed "unset or null" form.
+ - If you want to find out if a command is available on the user's
+   $PATH, you should use 'type <command>', instead of 'which <command>'.
+   The output of 'which' is not machine parseable and its exit code
+   is not reliable across platforms.
 
- - We use ${parameter#word} and its [#%] siblings, and their
-   doubled "longest matching" form.
+ - We use POSIX compliant parameter substitutions and avoid bashisms;
+   namely:
 
- - We use Arithmetic Expansion $(( ... )).
+   - We use ${parameter-word} and its [-=?+] siblings, and their
+     colon'ed "unset or null" form.
+
+   - We use ${parameter#word} and its [#%] siblings, and their
+     doubled "longest matching" form.
 
- - No "Substring Expansion" ${parameter:offset:length}.
+   - No "Substring Expansion" ${parameter:offset:length}.
 
- - No shell arrays.
+   - No shell arrays.
 
- - No strlen ${#parameter}.
+   - No strlen ${#parameter}.
 
- - No regexp ${parameter/pattern/string}.
+   - No pattern replacement ${parameter/pattern/string}.
+
+ - We use Arithmetic Expansion $(( ... )).
+
+ - Inside Arithmetic Expansion, spell shell variables with $ in front
+   of them, as some shells do not grok $((x)) while accepting $(($x))
+   just fine (e.g. dash older than 0.5.4).
 
  - We do not use Process Substitution <(list) or >(list).
 
@@ -65,6 +93,10 @@ For shell scripts specifically (not exhaustive):
      are ERE elements not BRE (note that \? and \+ are not even part
      of BRE -- making them accessible from BRE is a GNU extension).
 
+ - Use Git's gettext wrappers in git-sh-i18n to make the user
+   interface translatable. See "Marking strings for translation" in
+   po/README.
+
 For C programs:
 
  - We use tabs to indent, and interpret tabs as taking up to
@@ -105,7 +137,7 @@ For C programs:
 
  - Use the API.  No, really.  We have a strbuf (variable length
    string), several arrays with the ALLOC_GROW() macro, a
-   path_list for sorted string lists, a hash map (mapping struct
+   string_list for sorted string lists, a hash map (mapping struct
    objects) named "struct decorate", amongst other things.
 
  - When you come up with an API, document it.
@@ -124,3 +156,61 @@ For C programs:
    used in the git core command set (unless your command is clearly
    separate from it, such as an importer to convert random-scm-X
    repositories to git).
+
+ - When we pass <string, length> pair to functions, we should try to
+   pass them in that order.
+
+ - Use Git's gettext wrappers to make the user interface
+   translatable. See "Marking strings for translation" in po/README.
+
+Writing Documentation:
+
+ Every user-visible change should be reflected in the documentation.
+ The same general rule as for code applies -- imitate the existing
+ conventions.  A few commented examples follow to provide reference
+ when writing or modifying command usage strings and synopsis sections
+ in the manual pages:
+
+ Placeholders are spelled in lowercase and enclosed in angle brackets:
+   <file>
+   --sort=<key>
+   --abbrev[=<n>]
+
+ Possibility of multiple occurrences is indicated by three dots:
+   <file>...
+   (One or more of <file>.)
+
+ Optional parts are enclosed in square brackets:
+   [<extra>]
+   (Zero or one <extra>.)
+
+   --exec-path[=<path>]
+   (Option with an optional argument.  Note that the "=" is inside the
+   brackets.)
+
+   [<patch>...]
+   (Zero or more of <patch>.  Note that the dots are inside, not
+   outside the brackets.)
+
+ Multiple alternatives are indicated with vertical bar:
+   [-q | --quiet]
+   [--utf8 | --no-utf8]
+
+ Parentheses are used for grouping:
+   [(<rev>|<range>)...]
+   (Any number of either <rev> or <range>.  Parens are needed to make
+   it clear that "..." pertains to both <rev> and <range>.)
+
+   [(-p <parent>)...]
+   (Any number of option -p, each with one <parent> argument.)
+
+   git remote set-head <name> (-a | -d | <branch>)
+   (One and only one of "-a", "-d" or "<branch>" _must_ (no square
+   brackets) be provided.)
+
+ And a somewhat more contrived example:
+   --diff-filter=[(A|C|D|M|R|T|U|X|B)...[*]]
+   Here "=" is outside the brackets, because "--diff-filter=" is a
+   valid usage.  "*" has its own pair of brackets, because it can
+   (optionally) be specified only when one or more of the letters is
+   also provided.