Shell Programming and Scripting

#!/usr/bin/perl

use strict;
use warnings;
my $config_file="blub.config";

Config_Loader();




sub Config_Loader {
open(CONFIG,"$config_file") or die("config file not found $config_file");
my @config=<CONFIG>; 
close CONFIG;

foreach (@config) {
if ($_ !~ /#/){

	if (/\$userdb/){
	my @a = split(/=/,$_);
	my $userdb =  $a[1];
	print $userdb;
	}

	if (/\$extention/){
        }	

	print $userdb;
	my @charlist = `ls profiles/`;
	foreach(@charlist){print $_;}


}

}
}

# blub.config
# profiles/
$userdb=profiles/
# ignore following line
$another=blah/

Global symbol "$userdb" requires explicit package name at ./blub.pl line 29.
Execution of ./blub.pl aborted due to compilation errors.

$
$
$ cat -n blub1.pl
     1  #!/usr/bin/perl
     2  Config_Loader();
     3  sub Config_Loader {
     4    $_ = "ABC123XYZ";
     5    if (/ABC(123)XYZ/){
     6      my $x = $1;
     7      print "1) x = $x\n";
     8    }
     9    print "2) x = $x\n";
    10  }
$
$ perl blub1.pl
1) x = 123
2) x =
$
$

$
$
$ cat -n blub2.pl
     1  #!/usr/bin/perl
     2  use strict;   # added the "use strict" pragma
     3  Config_Loader();
     4  sub Config_Loader {
     5    $_ = "ABC123XYZ";
     6    if (/ABC(123)XYZ/){
     7      my $x = $1;
     8      print "1) x = $x\n";
     9    }
    10    print "2) x = $x\n";
    11  }
$
$ perl blub2.pl
Global symbol "$x" requires explicit package name at blub2.pl line 10.
Execution of blub2.pl aborted due to compilation errors.
$
$

$
$
$ cat -n blub3.pl
     1  #!/usr/bin/perl
     2  use strict;
     3  Config_Loader();
     4  sub Config_Loader {
     5    $_ = "ABC123XYZ";
     6    if (/ABC(123)XYZ/){
     7      my $x = $1;
     8      print "1) x = $x\n";
     9    }
    10    my $x;  # "use strict" will not complain now, but you'll not see the value either, because the $x at line 7 does not exist anymore.
    11    print "2) x = $x\n";
    12  }
$
$ perl blub3.pl
1) x = 123
2) x =
$
$

$
$ cat -n blub4.pl
     1  #!/usr/bin/perl
     2  use strict;
     3  my $x;
     4  Config_Loader();
     5  sub Config_Loader {
     6    $_ = "ABC123XYZ";
     7    if (/ABC(123)XYZ/){
     8      $x = $1;
     9      print "1) x = $x\n";
    10    }
    11    print "2) x = $x\n";
    12  }
$
$ perl blub4.pl
1) x = 123
2) x = 123
$
$

$
$
$ cat -n blub5.pl
     1  #!/usr/bin/perl
     2  Config_Loader();
     3  sub Config_Loader {
     4    $_ = "ABC123XYZ";
     5    if (/ABC(123)XYZ/){
     6      $x = $1;
     7      print "1) x = $x\n";
     8    }
     9    print "2) x = $x\n";
    10  }
$
$ perl blub5.pl
1) x = 123
2) x = 123
$
$

$
$
$ cat -n blub6.pl
     1  #!/usr/bin/perl
     2  $x = "";
     3  Config_Loader();
     4  sub Config_Loader {
     5    $_ = "ABC123XYZ";
     6    if (/ABC(123)XYZ/){
     7      $x = $1;
     8      print "1) x = $x\n";
     9    }
    10    print "2) x = $x\n";
    11  }
$
$ perl blub6.pl
1) x = 123
2) x = 123
$
$

$
$
$ cat -n blub7.pl
     1  #!/usr/bin/perl
     2  my $x;
     3  Config_Loader();
     4  sub Config_Loader {
     5    $_ = "ABC123XYZ";
     6    if (/ABC(123)XYZ/){
     7      $x = $1;
     8      print "1) x = $x\n";
     9    }
    10    print "2) x = $x\n";
    11  }
$
$ perl blub7.pl
1) x = 123
2) x = 123
$
$

$
$
$ cat -n blub.config
     1  # blub.config
     2  # profiles/
     3  $userdb=profiles/
     4  # ignore following line
     5  $another=blah/
$
$
$ cat -n blub.pl
     1  #!/usr/bin/perl
     2  use strict;
     3  use warnings;
     4
     5  my $config_file="blub.config";
     6  my $userdb;
     7
     8  Config_Loader();
     9  print "Outside the subroutine: userdb = ",$userdb;
    10
    11  sub Config_Loader {
    12    open(CONFIG,"$config_file") or die("config file not found $config_file");
    13    my @config=<CONFIG>;
    14    close CONFIG;
    15    foreach (@config) {
    16      if ($_ !~ /#/){    # this is TRUE for 2 lines, and $userdb is not flushed, hence the "Outside..." line is printed twice
    17        if (/\$userdb/){ # this is TRUE for 1 line, hence the "Inside..." line is printed once
    18          my @a = split(/=/,$_);
    19          $userdb =  $a[1];
    20          print "Inside the if condition: userdb = ",$userdb;
    21        }
    22        print "Outside the if condition: userdb = ",$userdb;
    23      }
    24    }
    25  }
$
$ perl blub.pl
Inside the if condition: userdb = profiles/
Outside the if condition: userdb = profiles/
Outside the if condition: userdb = profiles/
Outside the subroutine: userdb = profiles/
$
$