Can I read and write to multiple file descriptors at the same time (Perl)?

Question

I am trying to read from two files and generate output in the third. At first I wanted to edit the first one on the go, but I did not find a suitable method for saving arrays.

My problem is that the third file (output) is empty when I uncomment the function "_ref_param_handling". BUT , which puzzles me most: if I make UNIX a very simple `cat` system call in the output file at the end (see code below), it works fine. If I open the file descriptor just before this and close it right after editing, it also works fine (around my FILEHANDLE LIST sheet).

Undoubtedly, I missed something here. Besides the problem between my keyboard and my chair, what is it? File descriptor conflict? Problem with area?

Each variable is declared and has the value that I want to have.

Change (no longer applicable). Using IO :: File in three files did not change anything.

---

Edit 2: New full routine code

My code works (unless my ref already exists, but because of the "append" mode, which I think), but there may be some errors and incorrect coding methods (sorry, Monks). However, I use Strict and warnings !

sub _ref_edit($) {
    my $manda_def = "$dir/manda_def.list";
    my $newrefhandle;
    my $ref       = $_[0];
    (my $refout   = $ref) =~ s/empty//;
    my $refhandle;
    my $parname   = '';
    my $parvalue  = '';
    my @val;

    _printMan;

    my $flush = readline STDIN;    # Wait for <enter>

    # If one or both of the ref. and the default values are missing
    if ( !( -e $manda_def && -e $ref ) ) {
        die "Cannot find $ref and/or $manda_def";
    }

    # Open needed files (ref & default)
    open( $refhandle, "<", $ref ) or die "Cannot open ref $ref : $!";
    open( $newrefhandle, ">>", $refout ) 
      or die "Cannot open new ref $refout : $!";

    # Read each line
    while ( my $refline = <$refhandle> ) {
    # If line read not an editable macro
        if ( $refline =~ /^define\({{(.+)}},\s+{{.*__VALUE__.*}}\)/ ){
        $parname = $1;         # $1 = parameter name captured in regexp
        # Prompt user
        $parvalue = _ref_param_handling( $parname, $manda_def );   
        # Substitution in ref
        $refline =~ s/__VALUE__/$parvalue/;
        # Param not specified and no default value
        $parvalue eq '' ? $refline=~s/__COM__/#/ : $refline=~s/__COM__//; 
        }

    print $newrefhandle $refline;
    }
    close $newrefhandle;
    close $refhandle;

    return $refout;
}    # End ref edit  

the _ref_param_handle routine is still:

open( $mde, '<', $_[1] )
      or die "Cannot open mandatory/default list $_[1] : $!";

    # Read default/mandatory file list 
    while (<$mde>) {       
       ( $name, $manda, $default, $match, $descript ) = split( /\s+/, $_, 5 ); 
       next if ( $name !~ $ref_param );  # If param read differs from parname

    (SOME IF/ELSE)

    } # End while <MDE>
    close $mde;
    return $input;
}

Extract from manda_def file:

NAME  Mandatory? Default Match      Comm.
PORT          y NULL  ^\d+$ Database port
PROJECT       y NULL  \w{1,5}   Project name
SERVER        y NULL  \w+           Server name
modemRouting  n NULL  .+        
modlib        y bin   .+        
modules       y sms   .+

Extract from file ref_file:

define({{PORT}},         {{__VALUE__}})dnl
define({{PROJECT}},      {{__VALUE__}})dnl
define({{SERVER}},       {{__VALUE__}})dnl
define({{modemRouting}}, {{__COM__{{$0}} '__VALUE__'}})dnl
define({{modlib}},       {{__COM__{{$0}} '__VALUE__'}})dnl
define({{modules}},      {{__COM__{{$0}} '__VALUE__'}})dnl

Any help was appreciated.

Answer 1

, , .

script . ( ). ( )...

/me * *

24 ...

Answer 2

_ref_param_handle. , .
, , .
EDIT:
, :

#!/usr/bin/perl -w

sub test
{
 my $fh_to_read = $_[0] ;
 my $fh_to_write = $_[1] ;

 while(<$fh_to_read>)
 {
  print $fh_to_write  $_ ;
 }
 seek($fh_to_read,0,0) ;
}

open(FH1,"<dummy1");
open(FH2,"<dummy2");
open(FH3,">dummy3");

while(<FH2>)
{
 print FH3 "$_" ;
 test(\*FH1,\*FH3);
}

perl-

Answer 3

, $refhandle, $newrefhandle $mde. , , open - , .

, IO::File / , . - ...

use IO::File;

my $refhandle = IO::File->new("< $ref") or die "open() - $!";

$refhandle->print(...);

Regarding in-place editing of files, this is a common template that I use to achieve this, make sure the behavior -ifor Perl.

sub edit_file
{
    my ($filename) = @_;

    # you can re-create the one-liner above by localizing @ARGV as the list of
    # files the <> will process, and localizing $^I as the name of the backup file.
    local (@ARGV) = ($filename);
    local($^I) = '.bak';

    while (<>)
    {
        s/original string/new string/g;
    }
    continue
    {
        print;
    }
}

Answer 4

From what I'm compiling, your script wants to convert the file in the following form:

define({{VAR1}}, {{__VALUE__}})
define({{VAR2}}, {{__VALUE__}})
define({{VAR3}}, {{__VALUE__}})
define({{VAR4}}, {{__VALUE__}})

like that:

define({{VAR1}}, {{}})
define({{VAR2}}, {{VALUE2}})
define({{VAR3}}, {{VALUE3}})
define({{VAR4}}, {{}})

The following work. I do not know what manda_def means, and also I did not create a function to replace the actual variable.

#!/usr/bin/perl
use strict;
use warnings;

sub work {
    my ($ref, $newref, $manda_def) = @_;

    # Open needed files (ref & default)
    open(my $refhandle, '<', $ref) or die "Cannot open ref $ref : $!";
    open(my $newrefhandle, '>', $newref) or die "Cannot open new ref $newref: $!";

    # Read each line
    while (my $refline = <$refhandle>) {
        # if line read is not an editable macro
        if ($refline =~ /^define\({{(.+)}},\s+{{.*__VALUE__.*}}\)/){
            my $parvalue = _ref_param_handling($1, $manda_def); # manda_def?
            # Substitution in ref
            $refline  =~ s/__VALUE__/$parvalue/;
            # Param not specified and no default value
            $refline  =~ s/__COM__/#/ if $parvalue eq '';
        }
        print $newrefhandle $refline;
    }
    close $newrefhandle;
    close $refhandle;

    return $newref;
}

sub _ref_param_handling {
    my %parms = (VAR2 => 'VALUE2', VAR3 => 'VALUE3');
    return $parms{$_[0]} if exists $parms{$_[0]};
}

work('ref.txt', 'newref.txt', 'manda.txt');