I thought that the map function takes in a list(perhaps an array), I do not see the above code having a list passed to it.

unpack outputs a list. In this case it extracts a list of 6 numbers (ascii values) from the (first) 6 bytes in $octetstr.

It then uses map to iterate over those 6 numbers converting them to 2-digit hex strings and appending them to $val

Before spliting them (the 2-digit hex strings) back apart and then joining them again interspersed with ':'s.

It is an altogether overcomplicated and clumsy piece of code. The whole process can be done with just $mac = join ':', unpack '(H2)*', $octetstr;

Ie. Given:

$octetstr = join '', map chr(), 0xab, 0xcd, 0x00, 0x1d, 0x94, 0x56;;
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Instead of:

val = ''; 
map { $val .= sprintf("%02x",$_) } unpack "CCCCCC", $octetstr;;

$mac = join( ":", unpack("a2 a2 a2 a2 a2 a2", $val ) );;

print $mac;;
ab:cd:00:1d:94:56
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You could just do:

$mac = join ':', unpack '(H2)*', $octetstr;;

print $mac;;
ab:cd:00:1d:94:56
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