# hdparm -i /dev/hda

/dev/hda:

 Model=WDC WD307AA-00BAA0, FwRev=10.09K11, SerialNo=WD-WMA2F2556865
 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
 RawCHS=16383/16/63, TrkSize=57600, SectSize=600, ECCbytes=40
 BuffType=DualPortCache, BuffSize=2048kB, MaxMultSect=16, MultSect=1
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=60074784
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes: pio0 pio1 pio2 pio3 pio4
 DMA modes: mdma0 mdma1 mdma2 udma0 udma1 *udma2 udma3 udma4
 AdvancedPM=no WriteCache=enabled
 Drive Supports : Reserved : ATA-1 ATA-2 ATA-3 ATA-4

##</code><code>##

#!/usr/bin/perl

my $query = qx{hdparm -i /dev/hda} or die $!;

print "HDD serial number is: $1\n"
  if $query =~ m/SerialNo=([^,\s]+)/s;

##</code><code>##

HDD serial number is: WD-WMA2F2556865