I'm running into a strange issue with the unpack() function. I have a command which produces output in binary format which I'm trying to unpack into a hex string for parsing, printing, etc.. It appears that unpack() is removing a byte from the binary data when the hex string is created and I can't figure out why.

I put a small test script together to play around with it a bit and can work around it by writing the binary data to a file first then reading it back in but it seems quite bizarre that doing it the 2 ways would yield different results 

 use strict;

my $data = qx{sg_logs --page=0x34,1 pd1 -H -r > temp.bin};     
$data = qx{sg_logs --page=0x34,1 pd1 -H -r };                 
$data = unpack("H*", $data);

open OUTFILE1, ">", "outfile1.txt" or die $!;
print "unpacked1: ".$data."\n";    
print OUTFILE1 $data;
close OUTFILE1;
        
open FILE, "temp.bin" or die $!;
binmode FILE;

open OUTFILE2, ">", "outfile2.txt" or die $!;

while (<FILE>) {
    print "unpacked2: ".unpack('H*', $_ )."\n";
    print OUTFILE2 unpack('H*', $_);
}

close (FILE);
close (OUTFILE2);

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When I inspect the 2 output files created, outfile1.txt is always missing a byte in the same location ( 55th byte ) vs. outfile2.txt and of course, it's a byte I'm particularly interested in when parsing the results :) Comparing the 2 file sizes also shows the 2byte difference. Any help would be greatly appreciated!

In reply to unpack() removing data by shnatko

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