For shell scripts specifically (not exhaustive):
+ - We use tabs for indentation.
+
+ - Case arms are indented at the same depth as case and esac lines.
+
- 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.
+ - We use POSIX compliant parameter substitutions and avoid bashisms;
+ namely:
- - We use ${parameter#word} and its [#%] siblings, and their
- doubled "longest matching" form.
+ - We use ${parameter-word} and its [-=?+] siblings, and their
+ colon'ed "unset or null" form.
- - We use Arithmetic Expansion $(( ... )).
+ - 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).
- When we pass <string, length> pair to functions, we should try to
pass them in that order.
+
+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.