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Append to a file (from the beginning).

Mon, 10 Dec 2001 14:22:30 -0700

Description:
I've created a tagger. They are new, I guess, and they are very stupid. What you do is put in text it and writes it to a global file where people will read. It's like mixing a chat and a messageboard.

Code description:
The code for my tagger appends to the file. But append only appends to the end.

Here is my current code

open(WRITEFILE, ">>$file_path");
sysseek(WRITEFILE,0,0)	;
print WRITEFILE "-> $FORM{'tag'}\n";
close(WRITEFILE);

Problem:
I need the program to append to the beginning of the file. Not the end. But sysseek or seek won't let you WRITE to the file, only read from the point you specify. How can I write to the beginning?

Thanks much.<br>
-Mike
{InFeStEd-ArCh0n}

Re: Append to a file (from the beginning).

Fri, 21 Dec 2001 00:35:35 -0700

heres a simple solution

lets say your chat file is called ChatLog.txt.

Copy ChatLog.txt to a file called ChatLog.old
Then open ChatLog.txt for a write and print the new text into it then open the .old file and print that text into the new ChatLog.txt.

want some code??

sub CreateOldFile
{
my $file_fame = $_[0];
my $newname = substr($file_name, 0, rindex($file_name ,'.')) . '.old';
my $file_data;

open(COFINPUTFILE, "< $file_name");
open(COFOUTPUTFILE, "> $newname");
chmod(0777, $newname);
while($file_data = <COFINPUTFILE>)
{
print COFOUTPUTFILE $file_data;
}
close(COFOUTPUTFILE);
close(COFINPUTFILE);

return($newname);
}
my $new_text = "new text or form value";
my $file_name = "ChatLog.txt";
my $oldfile_name = CreateOldFile($file_name); #Copys file to a file called $file_name.old and returns the name
my $file_data;

open(CHATLOG, "> $file_name");
open(OLDCHATLOG, "< $oldfile_name");
select CHATLOG; #pipe output to CHATLOG handle
print $new_text . "\n";
while($file_data = <OLDCHATLOG>)
{
print $file_data;
}
select STDOUT;
close(OLDCHATLOG);
close(CHATLOG);

If that code isn't extremely easy for you to understand, then use it as best you can and go get a good book on PERL.

Re: Append to a file (from the beginning).

Thu, 07 Feb 2002 05:32:26 -0700

hey,

there is an eaier way to do it, but DrGonzos way is a safer way, anyway the easy way is to read the whole file into a scalar, add what u want to the end and then write it out again, eg:

open(INFILE,"data.txt") || die;
while(<INFILE>) { $buffer .= $_; }
close(INFILE);

$buffer = "Put here what you want at the start\n" . $buffer;

open(OUTFILE,">data.txt") || die;
print OUTFILE $buffer;
close(OUTFILE);

sorry im on windoze at the moment so i cant test the code but it all looks right, just make sure that you use DrGonzos method when the file starts getting into the megabytes range :)

Re: Append to a file (from the beginning).

Thu, 19 Sep 2002 14:43:29 -0700

: I need the program to append to the beginning of the file. Not the end. But sysseek or seek won't let you WRITE to the file, only read from the point you specify. How can I write to the beginning?
:

You could also do this:
1.) read the file into an array
2.) use shift() to append it
3.) write the file

Code:

open(FH, $filetoappend) || die "Couldn't open $filetoappend: $!";
my @file = <FH>;
close(FH);
shift @file, $appenddata;
open(FH, ">$filetoappend") || die "Couldn't open $filetoappend: $!";
foreach (@file){
print FH $_;
}
close(FH);

~~Perl~~Visual Basic~~JavaScript~~
SuperJoe

Re: Append to a file (from the beginning).

Tue, 13 Jan 2009 17:35:20 -0700

your code works but i may be doing something wrong
can u check it for me? i am getting extra
data printed out to the file:

http://pwinquist.com/blog.html

here is the perl:
#!/usr/local/bin/perl -w

print "Content-type:text/html\n\n";

read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'});
@pairs = split(/&/, $buffer);
foreach $pair (@pairs) {
($name, $value) = split(/=/, $pair);
$value =~ tr/+/ /;
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
$FORM{$name} = $value;
}

foreach $key (keys(%FORM)) {
"$key = $FORM{$key}\n";
}

#print MAIL "Hello Dudes . . .\n";

# print MAIL "$FORM{int1}\n";
# print MAIL "$FORM{int1}\n";

$now = localtime time;
# print "It is now $now\n";

$test1 = $FORM{comments};

$test2 = $FORM{name};

open(INFILE,"output7.txt") || die;
while(<INFILE>) { $buffer .= $_; }
close(INFILE);

$buffer = "\n\n$now\n$test2

says:\n$test1\n\n-------------------------------------------------------------------------------------------------------------------------------------\n\n" . $buffer;

open(OUTFILE,">output7.txt") || die;
print OUTFILE $buffer;
close(OUTFILE);

#reading
open(OUTFILE, "output7.txt") || die "Opening output7.txt: $!";
@test10=<OUTFILE>;
close(OUTFILE);

print <<EndHTML;

<html>
<head><title>Opinion</title> </head>
<body bgcolor=white>

Return to <a href="http://pwinquist.com/page1.html" target="_top">Las Vegas Sins & Scams</a>.

<table width=700><tr><td align=left>
<pre>
@test10 <br><br>
$buffer
</pre>
</td></tr></table>

Return to <a href="http://pwinquist.com/page1.html" target="_top">Las Vegas Sins & Scams</a>.

<hr width=100%>

</body>
</html>

EndHTML
;

sub dienice {
($errmsg) = @_;
print "<h2>Error</h2>\n";
print "$errmsg<p>\n";
print "</body></html>\n";
exit;
}

thanks

Re: Append to a file (from the beginning).

Tue, 13 Jan 2009 17:35:48 -0700