Date: Sun, 25 Aug 2024 04:08:58 +0200
From: Steffen Nurpmeso <stef...@sdaoden.eu>
Message-ID: <20240825020858.nrX4pFTm@steffen%sdaoden.eu>
| (The only thinkable answer is that the step that my MUA does,
| namely resolving $* as a single string first, does not happen,
| right?
That's correct. When (first) expanding $* the value of IFS
is irrelevant, except for expansions where field splitting won't
later be performed (ie: never would be performed, regardless of
the value of IFS) - eg: VAR=$* or more commonly "$*".
After the fields have been expanded, then the results of those
expansions are subject to field splitting, for which IFS is
relevant.
That is, given
set -- a b c
$* produces 3 fields, "a" "b" and "c" (not quoted of course)
which are then subject (individually) to field splitting.
If we had IFS=b then the middle field would turn into nothing,
leaving just "a" and "c".
| I really have to carefully read the standard on Monday.)
For this see XCU 2.5.2, the descriptions of the expansions of
the special parameters, $@ and $* are the first two listed.
When unquoted, they're identical:
Expands to the positional parameters, starting from one, initially
producing one field for each positional parameter that is set. When
the expansion occurs in a context where field splitting will be
performed, any empty fields may be discarded and each of the non-empty
fields shall be further split as described in Section 2.6.5.
After that, when the expansion is in a context where field splitting
won't be performed, then $* and $@ are processed differently - with
$@ only being defined in a few cases in this circumstance. 2.6.5
says how IFS is used to (potentially) break those fields up info smaller
fields.
For $* in a non-field-splitting context, it goes on to say:
When the expansion occurs in a context where field splitting will
not be performed, the initial fields shall be joined to form a
single field with the value of each parameter separated by the first
character of the IFS variable if IFS contains at least one character,
or separated by a <space> if IFS is unset, or with no separation if
IFS is set to a null string.
If that happens, since we know we're in a context where field splitting
doesn't happen, we're done (just quote removal to follow - as not doing
field splitting usually also means not doing pathname expansion - though
some shells will do pathname expansion on the word after a redirect operator,
sometimes.)
kre
