CodingGuidelines: do not use 'which' in shell scripts

[git.git] / Documentation / CodingGuidelines

diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index 483008699f923be17926e8ed938ae17868f6ddf5..45577117c2a02dd4a4f9e63e78139b3df665b8f2 100644 (file)
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -35,10 +35,22 @@ For shell scripts specifically (not exhaustive):
 
  - 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.
 
+ - 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 POSIX compliant parameter substitutions and avoid bashisms;
    namely: