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

I am making backups to two alternating USB sticks. The problem is that the sticks get different device letters although I use the same connection. This means that before making the backup I must check the letter on Explorer (I use Windows 8.1), then I have to feed it to the Perl script by hand; I want the script to find the letter all by itself.
I tried the following code but then I got a pop-up window telling me to insert a device:

my $dev = '';
$dev = 'G' if( -d 'G:\\af' );
$dev = 'H' if( -d 'H:\\af' );

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Re: Find device letter
by Corion (Patriarch) on Mar 20, 2014 at 20:46 UTC

    You can tell Windows not to pop up that window:

    BEGIN {
    if ($^O =~ /\bMSWin32\b|\bcygwin\b/) {
        require Win32::API;
        Win32::API->import();
        Win32::API->Import('kernel32', 'SetErrorMode', 'I', 'I');

        my $errormode = SetErrorMode(1); # fetch old error mode
        SetErrorMode(1 | $errormode); # no AbortRetryFail messages any
+more
    };
};

# Now, Windows won't ask you to insert a drive into an empty device

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[d/l]

      FYI, it is a bit easier to use the SetErrorMode() that is provided more directly via Win32API::File (a module that is even "core"). 

      use Win32API::File qw< SetErrorMode SEM_FAILCRITICALERRORS >;

SetErrorMode( SEM_FAILCRITICALERRORS() | SetErrorMode(0) );

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      - tye        

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Re: Find device letter
by wind (Priest) on Mar 21, 2014 at 01:02 UTC
    Can also work off the list of available drives: (tye)Re: List of Mounted Drives on Win32 
    use strict;
use Win32API::File qw(getLogicalDrives GetVolumeInformation );

my @drives = getLogicalDrives();
for my $d (@drives) {
    my @x = (undef)x7;
    GetVolumeInformation( $d, @x );
    print "$d $x[0] ($x[5])\n";
}

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    - Miller
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[d/l]

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