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 <gitster@xxxxxxxxx> --- Documentation/CodingGuidelines | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines index 0a39205c48..1cb77a871b 100644 --- a/Documentation/CodingGuidelines +++ b/Documentation/CodingGuidelines @@ -194,6 +194,20 @@ For shell scripts specifically (not exhaustive): have changed since then. We'd need to re-evaluate this rule, together with the rule in t/check-non-portable-shell.pl script. + - 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 $IFS unless quoted. + + DO NOT write: + + local variable=$value ;# wrong + local variable=$(command args) ;# wrong + + and instead write: + + local variable="$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. -- 2.44.0-501-g19981daefd
