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Re^5: Empty File Contents before writing

by RichardK (Parson)
on Feb 19, 2013 at 11:41 UTC ( #1019529=note: print w/replies, xml ) Need Help??


in reply to Re^4: Empty File Contents before writing
in thread Empty File Contnts before writing

The help for truncate says

The position in the file of FILEHANDLE is left unchanged. You may want + to call seek before writing to the file.

So, any ideas why your code works without needing a seek 0?

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Re^6: Empty File Contents before writing
by johngg (Abbot) on Feb 19, 2013 at 14:37 UTC

    You are right. I hadn't read the documentation carefully enough and hadn't spotted that. Running hexdump -C shows that a seek is indeed necessary.

    $ perl -Mstrict -Mwarnings -e ' > open my $fh, q{>}, q{rubbish} or die $!; > print $fh qq{A longish line of text\n}; > truncate $fh, 0 or die $!; > print $fh qq{Short\n}; > close $fh or die $!;' $ cat rubbish Short $ hexdump -C rubbish 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |......... +.......| 00000010 00 00 00 00 00 00 00 53 68 6f 72 74 0a |.......Sh +ort.| 0000001d $

    Thank you for the correction.

    Cheers,

    JohnGG

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[Corion]: hippo: Yeah, but at least two years ago, it still was close enough to 20% cut
[Corion]: But I have a very positive experience with a four day workweek and a three day weekend. I can't easily go back though to full money.
[Corion]: That is easy without having to pay for a house, a wife or children though. If I had any of these, or any two of these, the decision wouldn't be that easy.
[ambrus]: wait. I understand no wife and children, but how do you not have to pay for a house?
[hippo]: I had a low-paid job about 20 years ago and seriously considered going down to a 3-day week. Would have worked 60% of the time for about 80% of the cash.
[Corion]: ambrus: Well, I pay rent, but don't own a house with variable/ unforeseeable costs
[hippo]: The thesholds/benefits balance at the time was nuts.

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