[PATCH 20/20] CodingGuidelines: avoid "test <cond> -a/-o <cond>"

From: Elia Pinto <gitter.spiros@gmail.com>
Date: Jun 6, 2014, 14:56 UTC
Message-ID: <1402066563-28519-21-git-send-email-gitter.spiros@gmail.com>
In-Reply-To: <1402066563-28519-1-git-send-email-gitter.spiros@gmail.com>

The construct is error-prone; "test" being built-in in most modern shells, the reason to avoid "test <cond> && test <cond>" spawning one extra process by using a single "test <cond> -a <cond>" no longer exists.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
---
 Documentation/CodingGuidelines |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index f424dbd..2d426bc 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -106,6 +106,18 @@ For shell scripts specifically (not exhaustive):
    interface translatable. See "Marking strings for translation" in
    po/README.
 
+ - We do not write our "test" command with "-a" and "-o" and use "&&"
+   or "||" to concatenate multiple "test" commands instead, because
+   the use of "-a/-o" is often error-prone.  E.g.
+
+     test -n "$x" -a "$a" = "$b"
+
+   is buggy and breaks when $x is "=", but
+
+     test -n "$x" && test "$a" = "$b"
+
+   does not have such a problem.
+
 For C programs:
 
  - We use tabs to indent, and interpret tabs as taking up to

-- 
1.7.10.4