How do I get the substed drive letter in Perl?

Question

I need to get substed drive letter in Perl. Could anyone kindly help me? $ENV{SYSTEMDRIVE} does not work; it gives me real logical drive letter, not the substed one.

score 3 · Answer 1 · answered Dec 15 '08 at 07:42

3

Are you looking for Win32::FileOp?

answered Dec 15 '08 at 07:42

brian d foy

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"Can't locate Win32/FileOp.pm" and so on, but i am not sure it would help (anyway, thank you for effort) To be exact - I am using Windows XP. – Dungeo Dec 15 '08 at 08:10
You have to install the module first. – brian d foy Dec 15 '08 at 08:20

score 2 · Accepted Answer · edited Dec 28 '20 at 15:13

2

 perl -e 'use Cwd; print( substr(getcwd(),10,1 )) ' # prints 10th char.

edited Dec 28 '20 at 15:13

mosh

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answered Dec 15 '08 at 09:43

Dungeo

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paxdiablo · Answer 3 · 2008-12-15T08:43:21.520

If you want to do it yourself, you could capture the output of the subst command and process it, since it outputs all current substituted drives.

SUBST [drive1: [drive2:]path]
SUBST drive1: /D
    drive1:        Specifies a virtual drive to which you want to assign a path.
    [drive2:]path  Specifies a physical drive and path you want to assign to
                   a virtual drive.
    /D             Deletes a substituted (virtual) drive.
Type SUBST with no parameters to display a list of current virtual drives.

C:\Documents and Settings\Administrator\My Documents>subst r: c:\bin

C:\Documents and Settings\Administrator\My Documents>subst
    R:\: => C:\bin

In order to do this, you need a function to return the subst'ed output, as follows:

sub get_drive {
    my $drv = shift;
    my $ln;
    $drv = substr($drv,0,1);
    open (IN, "subst |");
    while ($ln = <IN>) {
            chomp ($ln);
            if ((substr($ln,0,1) eq $drv) && (substr($ln,1,6) eq ":\\: =>")) {
                    close (IN);
                    return substr($ln,8);
            }
    }
    close (IN);
    return $drv . ":\\";
}

print get_drive ("R:") . "\n";
print get_drive ("S:") . "\n";

This outputs:

C:\bin
S:\

on my system which has only the one subst'ed drive.

SUBST with no parameters could help, but I have many substed drives and it displays all of them - I want to get the only one, which I work on currently. — Dungeo, Dec 15 '08 at 08:11
That's why you'd have to process the output to select which one you want. See edited contents. — paxdiablo, Dec 15 '08 at 08:44

score 0 · Answer 4 · answered Aug 09 '19 at 23:44

(Really late response, I know) but just today I need something like this and Win32::FileOp would not compile on my system. So I invoked subst and substituted virtual drives with "real"; snippet follows:

use strict;
use Data::Dumper;
use feature 'say';

my $DB=1;

$Data::Dumper::Indent = 1;
$Data::Dumper::Terse  = 1;
my %Virt;

exit main();

sub main
{
    my $rtn;
    my (@args) = @_;
    open CMD,"subst|" or die "can't run subst command";
    while (<CMD>) {
        chomp;
        my ($drv, $path) = split(/:\\: => /);
        $Virt{$drv} = $path;
    }

    my %rset; # result set
    while (my ($d,$p) = each %Virt) {
        $rset{$d} = expand($p);
    }
    #D say Dumper rset => \%rset;
    return $rtn;
}

# recursive call if expanded path has another 'virtual' drive
sub expand
{
    my ($loc) = @_;
    my $rtn = undef;
    my ($drv, $path) =  split(/:\\/, $loc);
    if ($a = $Virt{$drv}) {
        #D say "$a $path";
        $rtn = "$a\\$path";
        $rtn = expand($rtn);
    } else {
        #D say "$drv $path";
        $rtn = "$drv:\\$path";
    }
    return $rtn;
}

Notes: I use #D for quickNdirty debug statements

I tested this to three levels i.e. w: subst to x:, x: subst to y: and y: subst to c:

How do I get the substed drive letter in Perl?

4 Answers4