From be34b51049d1628d1ba4f17e3c087fd01f15f988 Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Fri, 5 Apr 2024 17:08:58 -0700 Subject: [PATCH] CodingGuidelines: quote assigned value in 'local var=$val' Dash bug https://bugs.launchpad.net/ubuntu/+source/dash/+bug/139097 lets the shell erroneously perform field splitting on the expansion of a command substitution during declaration of a local or an extern variable. The explanation was stolen from ebee5580 (parallel-checkout: avoid dash local bug in tests, 2021-06-06). Signed-off-by: Junio C Hamano --- Documentation/CodingGuidelines | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines index 96eaeee205..30bf290418 100644 --- a/Documentation/CodingGuidelines +++ b/Documentation/CodingGuidelines @@ -192,6 +192,18 @@ For shell scripts specifically (not exhaustive): so we write "variable=value" and then "export variable" on two separate lines. + - Some versions of dash have broken variable assignment when prefixed + with "local", "export", and "readonly", in that the value to be + assigned goes through field splitting at $IFS unless quoted. + + (incorrect) + local variable=$value + local variable=$(command args) + + (correct) + local variable="$value" + local variable="$(command args)" + - Use octal escape sequences (e.g. "\302\242"), not hexadecimal (e.g. "\xc2\xa2") in printf format strings, since hexadecimal escape sequences are not portable.