The Tie::File module has an excellent way of treating a file like an array, and the synopsis provides all you need to know for basic usage :

    # This file documents Tie::File version 0.93

    tie @array, 'Tie::File', filename or die ...;

    for (@array) {
      s/PERL/Perl/g;         # Replace PERL with Perl everywhere in th
+e file
    }
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perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
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_________
broquaint

I use this one all the time. A quick example of broquaint's suggested technique (from the command line), to replace all capitalization permutations of the word 'perl' to 'Perl' in file perl.pl, and store the original in perl.pl.bak:

perl -pi.bak -e 's/\bperl\b/Perl/gi' perl.pl
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The (-i) switch is so easy for adjusting TEXT files. I use this so often, that in my login script, I set an alias for pie=perl -p -i~ -e. Easy as pie.

pie s/2002/2003/g *.html

However, -i really doesn't edit "in place," but it does a good simulation of it. It creates a new file and moves the old file to a backup extension. You may have problems with access control lists (ACLs) on some network file system implementations. Experiment.

The '+' modes for the open() function are designed for fixed-record DATA updating. Note both examples in (perldoc -f open) refer to database files. Not that you couldn't use the functions for text files, but it would be a horrible and unnecessary tangle of seek(), tell() and caching to avoid overwriting parts of the next line before it is read. Not to mention further complications for newline conversion entanglement.

I wish the docs were more clear about this, to avoid this recurring question.

--
[ e d @ h a l l e y . c c ]

use File::Data;

use strict;
use File::Data;

my $o_dat = File::Data->new('./t/example');
$o_dat->write("complete file contents\n");
$o_dat->prepend("first line\n"); # line 0
$o_dat->append("original second (last) line\n");
$o_dat->insert(2, "new second line\n"); # inc. zero!
$o_dat->replace('line', 'LINE');
print $o_dat->READ;
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--------------------------------
SV* sv_bless(SV* sv, HV* stash);

I looked at PerlFaq5 and modified that code a little.

#!/usr/bin/perl -w
use strict;
die "usage: $0 <file> <search pattern> <replace pattern>",
    unless @ARGV == 3;
my $searchFile = $ARGV[0];
my $searchPattern = $ARGV[1];
my $replacePattern = $ARGV[2];
my $tempFile = 'tmp$$';
open FILE, $searchFile  #opens file in read-only mode
        or die "Cannot open $searchFile in read-only mode. $!\n";
open TMP, '>'.$tempFile
        or die "Cannot create temp file. $!\n";

while (<FILE>) {
    chomp;
    if (/$searchPattern/i) {
    print "Match found...replacing at line $.\n";
    $_ =~ s/$searchPattern/$replacePattern/i;
    print TMP $_."\n";
    }else {
    print TMP $_."\n"
    }
}
close FILE;
close TMP;
unlink $searchFile;
rename $tempFile, $searchFile;
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$ your_script < your_input > your_output
$ mv your_output your_input
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Because I'm on Win2k :-{

Well, the real reason is that this isn't happening on the command line. But thanks anyway.

Cheers,
ibanix

$ echo '$0 & $0 &' > foo; chmod a+x foo; foo;

Ehm ... the only changes you'd have to make so that this does work under Win2k is to use move /Y<code> instead of <code>mv and to put perl before the script.pl.

And you might even do it like this:

perl script.pl < source.txt > result.txt && move /Y result.txt source.
+txt
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Where the && means "execute the second command only if the first one did not return an error"

Jenda
Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.
   -- Rick Osborne

Edit by castaway: Closed small tag in signature

Can you get away with installing cygwin?

A few modules you could use are DBD::SQLite, DBD::CSV, DBD::AnyData or Tie::CSV_File.

You should have a look on CPAN for more of these...

I may be contradicting my previous post, but my problem is not your
problem. There is a whole class of software that does what you are
are trying to do. This class of software is called text editors. If you have the where-with-all (I don't) you might want to look into
playing around with the source code of an open-source editors.

Also why just mess with a flat file DB when there are open-source
RDBMS you could use?

Good luck with your project!