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 <gitster@pobox.com>
Junio C Hamano committed
Apr 5, 2024 at 17:08 UTC
be34b51049d1628d1ba4f17e3c087fd01f15f988
1 file changed
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Documentation/CodingGuidelines
+12
@@ -192,6 +192,18 @@ For shell scripts specifically (not exhaustive):
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so we write "variable=value" and then "export variable" on two
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separate lines.
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+ - Some versions of dash have broken variable assignment when prefixed
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+ with "local", "export", and "readonly", in that the value to be
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+ assigned goes through field splitting at $IFS unless quoted.
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+
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+ (incorrect)
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+ local variable=$value
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+ local variable=$(command args)
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+
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+ (correct)
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+ local variable="$value"
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+ local variable="$(command args)"
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+
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- Use octal escape sequences (e.g. "\302\242"), not hexadecimal (e.g.
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"\xc2\xa2") in printf format strings, since hexadecimal escape
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sequences are not portable.