Re: Detect Plugged USB Flash Drive / CD in CDROM Drive

Hi! I tried to extract messages from the etc/mtab. Here's what I did, its very simple. I'm just beggining to learn RegEx, please bear with me hehe..

sub scan_cddvd {
    # mtab file /etc/mtab
    # cd/dvd signature /dev/sr0
    open(MYINPUTFILE, "</etc/mtab");
    my $cddvd_path = 'not found';
    while(<MYINPUTFILE>){
        my($line) = $_;
        chomp($line);
        if($line =~ m/^\/dev\/sr/){
            print "FOUND CD/DVD\n";
            print $line , "\n";
            #$line =~ /(\/media\/.*)\ /;
            $line =~ /(\/media\/\S+)\s+/;
            my $newline = $1;
            print $newline , "\n";
            while($newline =~ m/\\040/){
                $newline =~ s/\\040/ /;
            }
            print $newline , "\n";
            $cddvd_path = $newline
        }              
    }
    close MYINPUTFILE;
    return $cddvd_path;
}
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I made a timer of some sort and calls this function to determine if a CD / DVD is inside the drive.works pretty ok. :D hehe. I would be applying the same concept with usb flash drives. Instead of looking for /dev/sr, I'd be looking for /dev/sdb hehe.hope it would work just fine.

Mabuhay Civil Engineers! :D

Comment on Re: Detect Plugged USB Flash Drive / CD in CDROM Drive Download Code

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Re^2: Detect Plugged USB Flash Drive / CD in CDROM Drive by Perlbotics (Archbishop) on Nov 28, 2008 at 12:08 UTC
Your snipped might work for your PC only and you'll only see the last /dev/sr device - which might not be a CD or DVD at all. The following suggestion is only a tiny improvement: use strict; # returns list of CD/DVD mountpoints or empty list sub scan_cddvd { my @drives = (); my $mtabfile = "/etc/mtab"; open my $mtfh, "<", $mtabfile or die "cannot open $mtabfile - $!"; while( <$mtfh> ){ my ($dev, $mountpoint, $fstype, $options) = split /\s+/; next unless $fstype =~ /udf\|iso\d+/ && $options =~ /ro\b/; #ro: the /ro/-test above should skip CDRW too $mountpoint =~ s/\\(0\d+)/chr(oct($1))/eg; # resolve oct chars push @drives, $mountpoint; } close $mtfh; return @drives; } print "o <", join(">\no <", scan_cddvd), ">\n"; [download] Things to note: uses strict; avoids "not found" as a special failure-indicator; returns list of mountpoints; expands all octal escapes; less HW-dependent (e.g. IDE, SCSI, SATA, ...), e.g. not restricted to /dev/sdb; tries a little harder to find a CD or DVD (iso/udf,ro), uses 3 param open and die; no globs (MYINPUTFILE); implicit use of $_; will fail for derviant mtab-formats; ...	[reply] [d/l]

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Re^2: Detect Plugged USB Flash Drive / CD in CDROM Drive
by Perlbotics (Archbishop) on Nov 28, 2008 at 12:08 UTC

Your snipped might work for your PC only and you'll only see the last /dev/sr device - which might not be a CD or DVD at all. The following suggestion is only a tiny improvement:

use strict;

# returns list of CD/DVD mountpoints or empty list
sub scan_cddvd { 
    my @drives   = ();
    my $mtabfile = "/etc/mtab";

    open my $mtfh, "<", $mtabfile or die "cannot open $mtabfile - $!";
    while( <$mtfh> ){
      my ($dev, $mountpoint, $fstype, $options) = split /\s+/;
      next unless $fstype =~ /udf|iso\d+/ && $options =~ /ro\b/; 
      #ro: the /ro/-test above should skip CDRW too
      $mountpoint =~ s/\\(0\d+)/chr(oct($1))/eg;  # resolve oct chars
      push @drives, $mountpoint;
    }
    close $mtfh;

    return @drives;
}

print "o <", join(">\no <", scan_cddvd), ">\n";
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