in reply to Unable to run or troubleshoot a script...

If I trim the cruft, use DATA (because this is a sample and I don't want to use external files), provide the user and password as constants (because this is a sample and I don't want to use STDIN), then:

#!/usr/bin/perl

# read user data into a hash
while ($line = <DATA>) {
   chomp $line;
   ($u, $p) = split /:/, $line;
   $ubase{$u} = $p;

}

my $uname = 'larry';
my $passwd = 'lingo';
   # find command-line args in hash or exit
die "cannot find user $uname\n\t"
   if ! defined $ubase{$uname};
die "cannot validate user password\n\t"
   if $passwd ne $ubase{$uname};

print "Validated user name and password\n";

__DATA__
larry:lingo
tom:tonic
ellie:plasma

[download]

Prints:

Validated user anme and password

[download]

as expected. Perhaps you didn't provide a correct password?

More important is to be aware of a couple of bad things this example is teaching you. First, always use strictures (use strict; use warnings;). The textbook example doesn't. Second, use the three parameter open because it's safer and clearer. Often too it's helpful to give the user the system generated error for a failed operation - die "couldn't open task data file: $!\n\t" (note the $!).

DWIM is Perl's answer to Gödel

Replies are listed 'Best First'.
Re^2: Unable to run or troubleshoot a script...
by cgmd (Beadle) on Jun 26, 2007 at 03:37 UTC
    It appears the problem is related to my downloaded todo.users file, which, opened in the editor, shows as:
    larry:lingo
tom:tonic
ellie:plasma




                [ Read 4 lines (Converted from DOS format) ]
^G Get Help     ^O WriteOut     ^R Read File    ^Y Prev Page    ^K Cut
+ Text     ^C Cur Pos
^X Exit         ^J Justify      ^W Where Is     ^V Next Page    ^U UnC
+ut Text   ^T To Spell

    [download]
    The issue relates the message at the bottom of the editor screen: Read 4 lines (Converted from DOS format). Having copied the same list of users:passwords to a fresh editor screen, the script runs as anticipated.

    In what way does the downloaded "DOS format" disrupt this file?

    Thanks!

[reply]
[d/l]

      Most likely a difference in line end characters. "DOS" uses crlf where *nix uses lf and Mac uses cr.

      chomp (by default) removes the line end sequence used by the host OS so if you are running *nix and you have a file containing crlf line ends then you will get the cr left at the end of the line causing the password match to fail.

      DWIM is Perl's answer to Gödel
[reply]
        I'm interested in the explanation by GrandFather:

        chomp (by default) removes the line end sequence used by the host OS so if you are running *nix and you have a file containing crlf line ends then you will get the cr left at the end of the line causing the password match to fail.

        This being the case, is there a simple means to convert such DOS formated files to a 'nix format? My success in doing this, so far, has been to select, copy and paste the text to an empty 'nix file.

        Thanks for the several helpful comments!

[reply]

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