melguin has asked for the wisdom of the Perl Monks concerning the following question:

There is a script that I am trying to troubleshoot that sometimes waits to write a line previously printed to the filehandle until the filehandle is closed.

At the end of the script it does this: 

print FILE (scalar localtime)." ## Exit\n";
close FILE;

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which results in a line previously previously printed to be written to the file after the Exit line. However, if I do this: 
print FILE (scalar localtime)." ## Exit\n";
exit();
close FILE;

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everything is fine. It's probably not a good idea to exit before the close, so I'm looking for another way to get the same results.

many thanks great holders of wisdom.

Replies are listed 'Best First'.
Re: output caught in memory
by Wookie (Beadle) on Jul 26, 2001 at 20:33 UTC
    The easiest way to make sure the write occurs is to write it in two lines - and set your write buffers to instant write.

    So try this:
    $|=1; # $| is undef by default - which means use buffering - define it
+ as 1 - and it instantly writes.
print FILE scalar localtime;
print FILE " ## Exit\n";
close FILE;

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    Alternatively, you can try to build the entire entry into a variable first - then write it. So:
    $close = localtime;
print FILE "$close ## Exit\n";
close FILE;

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    I hope this helps :).

    Update: Remove quotes around scalar localtime in first code block (thanks MZSanford)
    game(Wookie,opponent) eq 'Wookie' ? undef $problem : remove_limbs(arms,opponent);
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Re: output caught in memory
by dragonchild (Archbishop) on Jul 26, 2001 at 20:38 UTC
    Or, if you used IO::File, just do something like: 

    use IO::File;
my $output = IO::File->new(">&STDOUT");
autoflush $out;

print $out "Some String\n";

$out->close;

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(jeffa) Re: output caught in memory
by jeffa (Bishop) on Jul 26, 2001 at 20:34 UTC
    Wrong answer - move along, nothing to see here . . .

    You can try END: 

    sub END {
    close FILE;
}

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    Jeff 

    R-R-R--R-R-R--R-R-R--R-R-R--R-R-R--
L-L--L-L--L-L--L-L--L-L--L-L--L-L--
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Re: output caught in memory
by melguin (Pilgrim) on Jul 26, 2001 at 20:43 UTC
    great.

    I had looked at the $| option and had declared it equal to 1 at the beginning of the script, but it didn't do anything (perhaps because I was using select to change the default output before printing?).

    What finally worked was adding the $| = 1 between the selects. So, I went from this: 

                                    # Change the output to logfile
                                $filehandle = select LOG_FILENAME;

                                eval $menu[$var];

                                # Restore the filehandle
                                select $filehandle;

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    to this: 
                                    # Change the output to logfile
                                $filehandle = select LOG_FILENAME;

                                $| = 1;
                                eval $menu[$var];

                                # Restore the filehandle
                                select $filehandle;

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    Many thanks to all.
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