On 12/11/10 19:35, Eric Blake wrote:
On 11/12/2010 11:17 AM, Harald van Dijk wrote:
(
:
:
:
:
:
)>test-$LINENO
should write to file test-1, not test-7, even though the only word is on
line 7. bash gets this wrong, pdksh gets this almost right.
Umm - there was more than one word in that example (each : in the
subshell is a word). But I agree that the subshell command itself
started on line 1, but the word containing $LINENO is on line 7.
That was because it was a poor example. I meant to use comments, but
forgot to change this before posting. I haven't checked if they count as
words in SUS, but they don't in the dash source code.
There are _so many_ variations on what this example would do that it's
hard to say that any one version is definitively correct. In general,
the standard tends to favor the ksh93 interpretation of things; but on
your example, it touches the file test-6 (not test-7 nor test-1).
>
All I can see in the standard is:
"Set by the shell to a decimal number representing the current
sequential line number (numbered starting with 1) within a script or
function before it executes each command."
with no hint as to whether LINENO auto-increments over the number of
newlines encountered while parsing that command.
You may be right. SUS doesn't really specify whether "current" refers to
the first or the last line number of a command. test-1 and test-7 are
equally defensible, so I was too quick to say that bash gets this wrong.
I hope you agree, though, that test-6 is iffy, and for my other example:
echo $LINENO \
$LINENO
two identical numbers must be printed. SUS only requires and only allows
LINENO to be set before a command is executed, so once it is set, it is
set for both expansions. Given that,
(
#
#
#
#
#
)>test-$LINENO \
>>test2-$LINENO
must not write to test-7 and test2-8. It may write to test-1 and
test2-1, or it may write to test-8 and test2-8. Perhaps even to test-7
and test2-7. Again, though, LINENO must be the same in both expansions.
So for dash, the problem doesn't change: storing the line number of each
word, rather than each command, makes it very hard to get LINENO right.
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