in reply to Empty File Contnts before writing

The function you seek is... seek

use strict;
use warnings;

open my $fh, ">", "testing1.txt";
print $fh "stat";
seek $fh, 0, 0;
print $fh "stat-updated";
close $fh;

system cat => "testing1.txt";

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package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

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Re^2: Empty File Contents before writing
by Athanasius (Archbishop) on Feb 19, 2013 at 08:01 UTC

    Yes, seek works in this case because the final output is longer than the initial output. But a word of caution is in order. Consider:

    #! perl
use strict;
use warnings;

my $filename = 'test.txt';
open(my $fh, '>', $filename) or die "Cannot open file '$filename' for 
+writing: $!";
print $fh "The quick brown fox jumped over the unfortunate dog.";
seek $fh, 0, 0;
print $fh "The final output.";
close($fh) or die "Cannot close file '$filename': $!";

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    This results in file “test.txt” containing:

    The final output.ox jumped over the unfortunate dog.

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    as seeking to the beginning of the file does not erase its existing contents.

    Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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[d/l]
[select]

      So I will have to open and close the file agin in order to completely truncate watever is written in previous write attempts?

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        There is also a built-in function called truncate that will do what you want.

        $ 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
$

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        Update: Added example code.

        Cheers,

        JohnGG

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[d/l]
      Yeah, gotta watch out for those output-oxen. ;-)

        So I need to open and close my file every time I print something to it so that it overwrites the previous print in the file?? Is there any other way coz I would have open and close the file numerous times.

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