bodmin has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

If my url is http://www.perlmonks.com/index.pl?node=Seekers, I am trying to get my script name, i.e. index.pl.

I use $ENV{REQUEST_URI} to get the current url.

I have some params attached to the url which I access via $ENV{QUERY_STRING}.

So in order to get index.pl (as in the example above) I use the following: 

  $attach1 = $ENV{REQUEST_URI};
  if($attach1 =~ /\\/){
    my @filename_parts = split /\\/,$attach1;
    my $length = scalar(@filename_parts);
    $attach1 = $filename_parts[--$length];
  }
  if($attach1 =~ /\//){
    my @filename_parts = split /\//,$attach1;
    my $length = scalar(@filename_parts);
    $attach1 = $filename_parts[--$length];
  }

[download]

The above gives me index.pl?node=Seekers, half way there.

To strip off ?node=Seekers I use the following: 

  $paramstr = "\?".$ENV{QUERY_STRING};
  $attach1 =~ s/$paramstr/;

[download]

And that is where my code breaks. How do I strip off the query string so I am left with index.pl?

Replies are listed 'Best First'.
Re: URL $ENV variables
by sgifford (Prior) on Aug 04, 2003 at 08:43 UTC
    I think you simply want: 
    $attach1 =~ s/\?.*$//;

    [download]
    But you seem to be doing this in an awfully complicated way, and your parsing code is fragile (it will fail on:
    http://www.perlmonks.com/index.pl?node=Smokers/Jokers
    , for example) Have you considered the URI module?

    Update: I see why you'd want to use $ENV{QUERY_STRING}. The problem with your code is that the double-quotes are eating the backslash---by the time the regex sees the question mark it's unbackslashed, and so doesn't make any sense. Single quotes won't do that (at least not with a question mark). You're also missing the replacement string on your regex. This code works for me: 

      $paramstr = '\?'.$ENV{QUERY_STRING};
  $attach1 =~ s/$paramstr//;

    [download]
    But it fails if there are slashes in the query part of the string.
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Re: URL $ENV variables
by antirice (Priest) on Aug 04, 2003 at 08:29 UTC

    Check out $0. For more information, perldoc perlvar.

    antirice    
    The first rule of Perl club is - use Perl
    The     ith rule of Perl club is - follow rule i - 1 for i > 1

[reply]
      I tried that but couldn't figure it out. there is no reference as to which $ENV variables there are in perl.
[reply]

        Check out this script for what environment variables are set. It's nice for debugging, but don't keep it on your server.

        #!/usr/bin/perl -w

use CGI qw(header start_html end_html);
print header(),start_html();
print "$_ = $ENV{$_}<br>" foreach (keys %ENV);
print "\$0 is $0";
print end_html();

        [download]

        Of course, you could just use CGI and use its url() or script_name() methods. For more on the syntax for the url() method, check out this link.

        antirice    
        The first rule of Perl club is - use Perl
        The         ith rule of Perl club is - follow rule i - 1 for i > 1

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[d/l]
        That's because $ENV is decided by the enviornment the script is running in. See antirice's post above this. Note that $ENV is different depending upon your server OS, and whatever else happens to be floating around on the system. Also note that there is a lot more stuff in $ENV when running a script on a webserver, then just running it on the command line. Printing all the keys in the enviornment you will use is basically the only way to be sure you know what's available.
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Re: URL $ENV variables
by snowcrash (Friar) on Aug 04, 2003 at 08:38 UTC
    Your code probably breaks because there's a syntax error in your substitution, you are missing on slash at the end. It should rather be $attach1 =~ s/$paramstr//;

    Anyway, I'd make use of the CGI modulue and its url() method. 
    use CGI;
my $q   = new CGI;
my $url = $q->url(-absolute => 1);

    [download]

    regards, snowcrash
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Re: URL $ENV variables
by jsprat (Curate) on Aug 04, 2003 at 08:47 UTC
    Is this is a standard CGI? If so, have a look at $ENV{SCRIPT_FILENAME} and $ENV{SCRIPT_NAME}. SCRIPT_FILENAME gives the absolute path to the running script and SCRIPT_NAME gives the virtual path to the script, both sans query string.

    If you want to see all environment variables available to your script, create a script that loops through all the keys of %ENV and prints all key/value pairs.

    HTH

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Re: URL $ENV variables
by naChoZ (Curate) on Aug 04, 2003 at 12:54 UTC
    You can do it with the URI module pretty easily: 

    #!/usr/local/bin/perl -w
use strict;
use URI;
 
my $url = 'http://www.example.com/foo/bar.pl?baz';

my $u1 = URI->new($url);
my @seg = $u1->path_segments;
print "file: $seg[-1] \n";

    [download]

    --
    "I just read perlman:perlboot," said Tom, objectively.
    naChoZ

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Re: URL $ENV variables
by chanio (Priest) on Aug 05, 2003 at 02:00 UTC
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