Public bug reported:
With Ubuntu (for many years), the following code in /bin/sh (i.e. dash):
f()
{
local v="$@"
echo "<$v>"
}
f "$@"
behaves differently to /bin/sh on Debian, macOS, FreeBSD, Solaris
(/usr/xpg4/bin/sh).
The behaviour of "$@" is very special. When there are no arguments, it
completely
disappears (i.e. even the surrounding quotes disappear so that there are no
words). When
there are arguments, it replicates those arguments perfectly (i.e. it
effectively produces
multiple quoted arguments if necessary).
The described behaviour applies when "$@" is used for local variable assignment
on Ubuntu,
which sounds consistent with other uses of "$@" and therefore correct, but it
doesn't
match the behaviour on any other system, and is therefore a problem for shell
portability.
On the other systems mentioned above, the behaviour of "$@" when used as the
value of a
variable assignment (local or not) is as though "$*" had been used (i.e. it
produces a
single argument containing all the words).
The difference is clear when the arguments contain multiple words. On Ubuntu,
only
the first word is assigned to v. Any subsequent words are treated as subsequent
variable
names. This goes unnoticed if the subsequent words are valid variable
identifiers.
But if the subsequent words are not valid identifiers, then dash emits a "bad
variable name"
error message.
Note that without the "local" keyword, "$@" does behave like "$*" (like
all the other systems).
You might think that this is correct behaviour, but it is contrary to non-local
variable
assignment, and contrary to all other systems, and is therefore unhelpful.
Please change
it to behave like dash on other systems, e.g. debian.
This behaviour has been witnessed on ubuntu-16.x and ubuntu-20.04.
** Affects: dash (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1943964
Title:
local var="$@" doesn't behave like every other system
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