in reply to Regexp Substitution on previously opened filehandle

Oh, I see the problem. You can't just s/// on a line from a read-write filehandle and have the changes reflected in the file. You need to print the changed line back to the file. And that gets ugly and tricky if the size of the line has changed. You'd be best to do: 
while (<FILE_1>) {
  if (/regex/) {
    s/.../.../;
    s/.../.../;
    print FILE_2;
  }
}

[download]
Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

Replies are listed 'Best First'.
Re^2: Regexp Substitution on previously opened filehandle
by Roy Johnson (Monsignor) on Dec 29, 2005 at 16:09 UTC
    Or use Tie::File to pretend you're working on an array. Then the s/// would affect the lines in the file.
    Caution: Contents may have been coded under pressure.
[reply]
[d/l]
Re^2: Regexp Substitution on previously opened filehandle
by ghenry (Vicar) on Dec 29, 2005 at 17:32 UTC

    Thanks, one of those days again (which I seem to be having more of). Just needed to change the print statement a bit.

    Final version: 

    #!/usr/bin/perl -w
#=====================================================================
+==========
#
#         FILE:  create_seq_test.pl
#
#        USAGE:  ./create_seq_test.pl
#
#  DESCRIPTION:  Test script to "create sequences" from backup sql fil
+e
#
#      OPTIONS:  ---
# REQUIREMENTS:  ---
#         BUGS:  ---
#        NOTES:  ---
#       AUTHOR:  Gavin Henry (GH), <ghenry@suretecsystems.com>
#      COMPANY:  Suretec Systems Ltd.
#      VERSION:  1.0
#      CREATED:  29/12/05 14:42:44 GMT
#     REVISION:  ---
#=====================================================================
+==========

use strict;
use warnings;
use Carp;
use Readonly;
use Regexp::DefaultFlags; # Adds xms to the end of all Regexp
use diagnostics;          # More helpful error messages, comment out l
+ater
$| = 1;                   # Set the autoflush flag to on

Readonly my $import_seqs  => 'dbexp.sql';
Readonly my $create_seqs  => 'cre_seq.sql';

open my $CREATE_SEQS, '+>', $create_seqs     # using indirect filehand
+les, r/w
    or croak "Can't open '$create_seqs': $!";

open my $SQL_TO_GREP, '<', $import_seqs      # three-argument form is 
+more robust
    or croak "Can't open '$import_seqs': $!";

while ( <$SQL_TO_GREP> ) {
    if ( /\A SELECT [ ] pg_catalog [.] setval [(]/ ) {

        s{\A                                         # Substitute from
+ start of line
            SELECT [ ] pg_catalog [.] setval [(] ['] # Replace this, w
+hich uses singular
                                                     # Character class
+es to escape
                                                     # metacharacters,
+ including spaces

        }
        {CREATE SEQUENCE imp.};         

        s{ ['] [,] [ ] }{ INCREMENT BY 1 START WITH };

        s{ [,] [ ] false [)] ; }{;};

        s{ [,] [ ] true [)] ; }{;};

        print $CREATE_SEQS $_;
        }

}
close $SQL_TO_GREP or croak "Couldn't close '$import_seqs': $!";
close $CREATE_SEQS or croak "Couldn't close '$create_seqs': $!";

print "Create Sequence statements file complete.\n"

    [download]

    Walking the road to enlightenment... I found a penguin and a camel on the way.....
    Fancy a yourname@perl.me.uk? Just ask!!!
[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom