On 24/11/2024 11:58, Herbert Xu wrote:
On Sat, Nov 23, 2024 at 04:22:52AM +0100, Christoph Anton Mitterer wrote:
@Herbert, you've said that you believe dash's behaviour is POSIX
compliant.
But I still couldn't find anything in the text which would imply
this... and Harald who typically knows things quite well also seems to
believe that POSIX doesn't allow it.
It's simple really, POSIX says:
or any command of an AND-OR list other than the last.
The word "command" refers to the commands that make up the AND-OR
list. Command substitution is not part of that at all.
Isn't it? Taking the rest of the sentence along with it:
The -e setting shall be ignored when executing [...] any command of an
AND-OR list other than the last.
So, given
set -e
test -n "$(false; echo x)" && echo x
the -e setting shall be ignored when executing
test -n "$(false; echo x)"
That much I think is not in doubt.
What does it mean for that command to be executed? 2.9.1.1 Order of
Processing says:
When a given simple command is required to be executed (that is, when
any conditional construct such as an AND-OR list or a case statement
has not bypassed the simple command), the following expansions,
assignments, and redirections shall all be performed from the
beginning of the command text to the end:
[...]
2. [...] For all other command names, words after the word that
produced the command name shall be subject only to regular
expansion.
[...]
That is, the expansion of words in a simple command is considered part
of the execution of that command. When the "false; echo x" is being
executed, this is part of the execution of test -n "$(false; echo x)".
Because that test -n "$(false; echo x)" command is being executed, and
it is a command of an AND-OR list other than the last, by what POSIX
says, the set -e setting shall be ignored.
Cheers,
Harald van Dijk
