Esteemed Monks, I have files where I need to replace values in specific places. The standard line lengths ar 210 characters and I need to change the characters in positions 100 and 149 only. I also need to ignore any line that begins with a 2. When this outputs I need to preserve the lines beginning with a 2 and output each line until completion but I cannot get any "foreach" statement to function correctly. I would rather not load the file in memory as the files will often have up to a million lines each and this definitely takes a hit on CPU performance. Any suggestions, solutions, or better ways of doing this are welcome. Thanks in advance -- Perl Newbie 
use File::Copy;

my($input_file) = $ARGV[0];
my($output_file) = $ARGV[1];

if ( !defined($input_file) || !defined($output_file) ) {
    print "Error: usage: ss7jurisdiction input_file  output_file\n";
}
else {
    # -----Backup the input files in case of error-----
    copy( $input_file, $input_file . ".bak" ) or
        die "Could not backup file $input_file to $input_file.bak: $!\
+n";

    # -----Attempt to open all of the files-----
    open( INFILE, $input_file ) || die( "Could not read input file 1 (
+$input_file): $!" );
    open( OUTPUT, "> " . $output_file ) || die( "Could not open output
+ file ($output_file): $!" );

    while (<INFILE>) {
        my $line = $_;
        chomp($line);

        # -----A line starting with a '2' is a header and is left unch
+anged
        if ( $line !~ m/^2/ ) {

            # -----Locate postions 100 and 149
            $juris1 = substr( $line, 99, 1 );
            $juris2 = substr( $line, 148, 1 );

            $juris1 = "9";
            $juris2 = "Z";

        # -----Generate the output string-----
        $output_line = substr( $line, 0, 98 ) 
        . $juris1 . substr( $line, 100, 48 )
        . $juris2 . substr( $line, 149, 61 ) 
        . "\n";

        print OUTPUT $output_line;
        last;
        }
    }

    # -----Close all of the files-----
    close( INFILE );
    close( OUTPUT );
}

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In reply to Replacing Text At Specific Positions by sheasbys

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