truncate or trunc

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

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Re: truncate or trunc by Fletch (Bishop) on Apr 25, 2008 at 16:30 UTC
No, truncate is a builtin part of the language. Perhaps if you provided sample code which exhibits the problem or an actual error message someone could possibly hope to help? See also How (Not) To Ask A Question. The cake is a lie. The cake is a lie. The cake is a lie.	[reply]
Re: truncate or trunc by citromatik (Curate) on Apr 25, 2008 at 16:34 UTC
What errors do you have? This works for me: `open my $fh, "+<", $filename or die $!; truncate $fh,$pos or die $!;` [download] or directly `truncate $filename,$pos or die $!;` Hope this helps citromatik	[reply] [d/l] [select]
Re: truncate or trunc by mr_mischief (Monsignor) on Apr 25, 2008 at 16:37 UTC
Does this give the error: `open my $file, '+>', 'testfile' or die "Can't write testfile: $!\n"; print $file 'test!'; seek $file, 0, 0; print <$file> . "\n"; seek $file, 0, 0; truncate $file, 0 or die "Can't truncate testfile: $!\n"; close $file or die "Can't save testfile: $!\n";` [download] If so, what's the error? truncate says that if truncate isn't implemented it's a fatal error, but I'm not sure what OSes that would include. BTW, it's usually a good idea to show us what you've tried so we can work from that.	[reply] [d/l]
Re: truncate or trunc by apl (Monsignor) on Apr 25, 2008 at 16:33 UTC
To expand on what Fletch said, truncate requires two parameters, the second being the length of the file you wish to have left. Did you specify anything other than the filehandle?	[reply]
Re: truncate or trunc by jscjso (Initiate) on Apr 25, 2008 at 16:59 UTC
Hi, Thanks for the quick replies. Here is my code: while (<DATA>){ unless (/$data_line_old/i){ my $read_position = tell DATA; seek DATA, $write_position, 0; print DATA $_; $write_position = tell DATA; seek DATA, $read_position, 0; } } truncate DATA, $write_position; close DATA; I tried to remove old lines from a text file. The tell and seek monitor the positions of the existing file and temporary file that it is creating. At the end of the creation. I try to use the truncate or trunc to cut the finished file to the right size(length). After the confidence you gave about the truncate, I tried again a few more times and discovered what went work. I initial used trunc and it errors me out as: Can't locate object method "trunc" via package "IO::Handle" at myProfile_pl.pl line 514, <DATA> line 10. Since this error, the original file got messed up. Then the truncate went wild after a few runs. The text file became super long with wrong length. I have it working now. Thanks, Jason	[reply]
Re^2: truncate or trunc by apl (Monsignor) on Apr 25, 2008 at 17:08 UTC
Please bracket your code with <code> and </code>. Thanks. I assume you opened a file with the filehandle DATA? Please change that to something else. DATA is reserved for a block of sample data within your program. Then you might consider testing your error returns...	[reply]